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ap biology midterm

units 1-7
STUDY
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natural selection
differential success in the reproduction of different phenotypes resulting from the interaction of organisms with their environment; population can change over generations if individuals that possess certain heritable traits leave more offspring than other individuals
evolutionary adaptation
an accumulation of inherited characteristics that enhance organisms' ability to survive and reproduce in specific environments
evolution
a change over time in the genetic composition of a population
taxonomy
the branch of biology concerned with naming and classifying organisms
fossils
remains or traces of organisms from the past
sedimentary rocks
rock formed from sand and mud that once settled in layers on the bottom of seas, lakes, and marshes- often rich in fossils
paleontology
the study of fossils
catastrophism
the hypothesis by Georges Cuvier that each boundary between strata corresponded in time to a catastrophe, such as a flood or drought, that had destroyed many of the species living there at that time
gradualism
the idea that profound change can take place through the cumulative effect of slow but continuous processes
uniformatarianism
Charles Lyell's idea that geologic processes have not changed throughout Earth's history
descent with modification
Darwin's initial phrase for the general process of evolution
artificial selection
the selective breeding of domesticated plants and animals to encourage the occurrence of desirable traits
homology
similarity in characteristics resulting from a shared ancestry
homologous structures
structures in different species that are similar because of common ancestry
vestigial organs
a structure of marginal, if any, importance to an organism; historical remnants of structures that had important functions in ancestors
biogeography
the study of the past and present distribution of species
endemic
species that are confined to a specific, relatively small geographic area
microevolution
evolutionary change below the species level; change in the genetic makeup of a population from generation to generation
population genetics
the study of how populations change genetically over time
modern synthesis
a comprehensive theory of evolution emphasizing populations as units of evolution and integrating ideas from many fields, including genetics, statistics, paleontology, taxonomy, and biogeography
population
a localized group of individuals that are capable of interbreeding and producing fertile offspring
gene pool
the total aggregate of genes in a population at any one time
Hardy-Weinberg theorem
the principle that frequencies of alleles and genotypes in a population remain constant from generation to generation, provided that only Mendelian segregation and recombination of alleles are at work
Hardy-Weinberg equilibrium
a state in which a population has the same allele frequencies from one generation to the next; conditions- 1) extremely large population size 2) no gene flow 3) no mutations 4) random mating 5) no natural selection
mutations
changes in the nucleotide sequence of DNA
duplication
an aberration in chromosome structure due to fusion with a fragment from a homologous chromosome, such that a portion of a chromosome is duplicated
genetic drift
unpredictable fluctuations in allele frequencies from one generation to the next because of a population's finite size
bottleneck effect
genetic drift resulting from the reduction of a population, typically by a natural disaster, such that the surviving population is no longer genetically representative of the original population
founder effect
genetic drift that occurs when a few individuals become isolated from a larger population, with the result that the new population's gene pool is not reflective of the original population
gene flow
genetic additions to and/or subtractions from a population resulting from the movement of fertile individuals or gametes
phenotypic polymorphism
the existence of two or more distinct morphs, each represented in a population in high enough frequencies to be readily noticeable
morphs
different forms of a discrete character
genetic polymorphism
the existence of two or more distinct alleles at a given locus in a population's gene pool
average heterozygosity
the percent, on average, of a population's loci that are heterozygous in members of the population
geographic variation
differences between the gene pools of separate populations or population subgroups
cline
a graded change in a trait along a geographic axis
fitness
the contribution an individual makes to the gene pool of the next generation, relative to the contributions of other individuals
relative fitness
the contribution of a genotype to the next generation compared to the contributions of alternative genotypes for the same locus
directional selection
natural selection that favors individuals at one end of the phenotypic range
disruptive selection
natural selection that favors individuals on both extremes of a phenotypic range over intermediate phenotypes
stabilizing selection
natural selection that favors intermediate variants by acting against extreme phenotypes
balancing selection
natural selection that maintains stable frequencies of two or more phenotypic forms in a population
balanced polymorphism
the ability of natural selection to maintain diversity in a population
heterozygote advantage
greater reproductive success of heterozygous individuals compared to homozygotes; tends to preserve variation in gene pools
frequency-dependent selection
a decline in the reproductive success of a morph resulting from the morph's phenotype becoming too common in a population; a cause of balanced polymorphism in populations
neutral variation
genetic diversity that confers no apparent selective advantage
pseudogenes
genes that have become inactivated by mutations
sexual selection
natural selection for mating success
sexual dimorphism
marked differences between the sexes in secondary sexual characteristics, which are not directly associated with reproduction
intrasexual selection
a direct competition among individuals of one sex (usually the males in vertebrates) for mates of the opposite sex
intersexual selectoin
selection whereby individuals of one sex (usually females) are choosy in selecting their mates from individuals of the other sex; also called mate choice
speciation
the origin of a new species in evolution
macroevolution
evolutionary change above the species level, including the appearance of major evolutionary developments, such as flight, that we use to define higher taxa
species
a group whose members possess similar anatomical characteristics and have the ability to interbreed
biological species concept
definition of a species as a population or group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring, but are not able to produce viable, fertile offspring with members of other populations
reproductive isolation
the existence of biological factors (barriers) that impede members of two species from producing viable, fertile hybrids
prezygotic barrier
a reproductive barrier that impedes mating between species or hinders fertilization of ova if interspecific mating is attempted
postzygotic barriers
any of several species-isolating mechanisms that prevent hybrids produced by two different species from developing into viable, fertile adults
morphological species concept
characterizes a species by its body shape, size, and other structural features
paleontological species concept
definition of species based on morphological differences known only from the fossil record
ecological species concept
defining species in terms of ecological roles (niches)
phylogenetic species concept
defines a species as a set of organisms with a unique genetic history- as one branch on the tree of life
sibling species
species that appear so similar that they cannot be distinguished on morphological grounds
allopatric speciation
a mode of speciation induced when an ancestral population becomes segregated by a geographic barrier or is itself divided into two or more geographically isolated subpopulations
sympatric speciation
a mode of speciation occurring as a result of a radical change in the genome of a subpopulation, reproductively isolating the subpopulation from the parent population
polyploidy
a chromosomal alteration in which the organism possesses more than two complete chromosome sets
allopolyploid
a common type of polyploid species resulting from two different species interbreeding and combining their chromosomes
adaptive radiation
the emergence of numerous species from a common ancestor introduced into an environment that presents a diversity of new opportunities and problems
punctuated equilibrium
in evolutionary theory, long periods of apparent stasis (no change) interrupted by relatively brief periods of sudden change
heterochrony
evolutionary change in the timing or rate of an organism's development
allometric growth
the variation in the relative rates of growth of various parts of the body, which helps shape the organism
paedomorphosis
the retention in an adult organism of the juvenile features of its evolutionary ancestors
homeotic genes
any of the genes that control the overall body plan of animals and plants by controlling the developmental fate of groups of cells
species selection
a theory maintaining that species living the longest and generating the greatest number of species determine the direction of major evolutionary trends
phylogeny
the evolutionary history of a species or group of related species
systematics
the analytical study of the diversity and relationships of organisms, both present day and extinct
molecular systematics
the comparison of nucleic acids or other molecules in different species to infer relatedness
fossil record
the chronicle of evolution over millions of years of geologic time engraved in the order in which fossils appear in rock strata
analogy
similarity between two species that is due to convergent evolution rather than to descent from a common ancestor with same trait
homoplasis
similar structure or molecular sequence that has evolved independently in two species
binomial
the two-part format of the scientific name
genus
first part of the binomial
specific epithet
second part of the binomial
domain kingdom phylum class order family genus species
order of organism classification
taxon
the named taxonomic unit at any level
phylogenetic trees
a branching diagram that represents a hypothesis about evolutionary relationships
cladogram
a diagram depicting patterns of shared characteristics among species
clade
a group of species that includes an ancestral species and all its descendants
cladistics
the analysis of how species may be grouped into clades
monophyletic
pertaining to a grouping of species consisting of an ancestral species and all its descendants; a valid clade
paraphyletic
pertaining to a grouping of species that consists of an ancestral species and some, but not all, of its descendants; lacking information about some members of a clade
polyphyletic
pertaining to a grouping of species derived from two or more different ancestral forms
shared primitive character
a character displayed in species outside a particular taxon
shared derived character
an evolutionary novelty that evolved within a particular clade
outgroup
a species or group of species that is closely related to a group of species being studied, but clearly not as closely related as any study-group members are to each other
ingroup
in a cladistic study of evolutionary relationships among taxa of organisms, the group of taxa that is actually being analyzed
phylogram
a phylogenetic tree in which the lengths of the branches reflect the number of genetic changes that have taken place in a particular DNA or RNA sequence in the various lineages
ultrametric tree
a phylogenetic tree in which the lengths of the branches reflect measurements of geologic time
maximum parsimony
a principle that states that when considering multiple explanations for an observation, one should first investigate the simplest explanation that is consistent with the facts
maximum likelihood
a principle that states that when considering multiple phylogenetic hypotheses, one should take into account the one that reflects the most likely sequence of evolutionary events, given certain rules about how DNA changes over time
orthologous genes
homologous genes that are passed in a straight line from one generation to the next but have ended up in different gene pools because of speciation
paralogous genes
homologous genes that are found in the same genome due to gene duplication
molecular clock
an evolutionary timing method based on the observation that at least some regions of genomes evolve at constant rates
neutral theory
the hypothesis that much evolutionary change in genes and proteins has no effect on fitness and therefore is not influenced by Darwinian natural selection
horizontal gene transfer
genes are transferred from one genome to another through mechanisms such as transposable elements, and perhaps through fusions of different organisms
protobionts
aggregates of abiotically produced molecules surrounded by a membrane or membrane-like structure
ribozymes
enzyme-like RNA molecules that catalyze reactions during RNA splicing
radiometric dating
a method paleontologists use for determining the ages of rocks and fossils on a scale of absolute time, based on the half-life of radioactive isotopes
half life
the number of years it takes for half of the original sample to decay
geologic record
the division of Earth's history into time periods, grouped into three eras: Archaean, Proterozoic, and Phanerozoic, and further subdivided into eras and epochs
stromatolites
rocklike structures composed of many layers of bacteria and sediment
serial endosymbiosis
a model of the origin of eukaryotes consisting of a sequence of endosymbiotic events in which mitochondria, chloroplasts, and perhaps other cellular structures were derived from small prokaryotes that had been engulfed by larger cells
genetic annealing
the production of a new genome through the transfer of part of the genome of one organism to another organism
snowball Earth hypothesis
the hypothesis that glaciers covered the planet's landmasses from pole to pole 750-570 million years ago, confining life to very limited areas
colonies
collections of autonomously replicating cells
Pangaea
the supercontinent formed near the end of the Paleozoic era when plate movements brought all the landmasses of Earth together
three domain system
a system of taxonomic classification based on three "superkingdoms": Bacteria, Archaea, and Eukarya
fermentation
catabolic process; a partial degradation of sugars that occurs without the use of oxygen
cellular respiration
catabolic pathway; oxygen is consumed as a reactant along with the organic fuel to produce ATP
redox reaction
a chemical reaction involving the transfer of one or more electrons from one reactant to another
reduction
addition of electrons to another substance
oxidation
the loss of electrons from one substance
reducing agent
the electron donor in a redox reaction
oxidizing agent
the electron acceptor in a redox reaction
NAD+
a coenzyme present in all cells that helps enzymes transfer electrons during the redox reactions of metabolism
electron transport chain
a sequence of electron carrier molecules that shuttle electrons during the redox reactions that release energy used to make ATP
glycolysis
the splitting of glucose into pyruvate
citric acid cycle
a chemical cycle involving 8 steps that completes the metabolic breakdown of glucose molecules to carbon dioxide; occurs within the mitochondrion; the second major stage in cellular respiration
oxidative phosphorylation
the production of ATP using energy derived from the redox reactions of an electron transport chain
substrate-level phosphorylation
the formation of ATP by directly transferring a phosphate group to ADP from an intermediate substrate in catabolism
acetyl coA
the entry compound for the citric acid cycle in cellular respiration, formed from a fragment of pyruvate attached to a coenzyme
cytochromes
iron-containing proteins; components of the electron transport chains in mitochondria and chloroplasts
ATP synthase
protein complex/enzyme that makes ATP from ADP and inorganic phosphate
chemiosmosis
an energy-coupling mechanism that uses energy stored in the form of a hydrogen ion gradient across a membrane to drive cellular work, such as the synthesis of ATP
proton-motive force
the potential energy stored in the form of an electrochemical gradient, generated by the pumping of hydrogen ions across biological membranes during chemiosmosis
aerobic
referring to an organism, environment, or cellular process that requires oxygen
anaerobic
referring to an organism, environment, or cellular process that lacks oxygen
alcohol fermentation
the conversion to pyruvate to carbon dioxide and ethyl alchohol
lactic acid fermentation
the conversion of pyruvate to lactate with no release of carbon dioxide
facultative anaerobe
an organism that makes ATP by aerobic respiration if oxygen is present but that switches to fermentation under anaerobic conditions
beta oxidation
a metabolic sequence that breaks fatty acids down to two-carbon fragments that enter the citric acid cycle as acetyl coA
photosynthesis
the conversion of light energy to chemical energy that is stored in glucose or other organic compounds; occurs in plants, algae, and certain prokaryotes
autotroph
an organism that obtains organic food molecules without eating other organisms or substances derived from other organisms; use energy from the sun or from the oxidation of inorganic substances to make organic molecules from inorganic ones; "self feeders"
heterotroph
an organism that obtains organic food molecules by eating other organisms or their by-products
chlorophyll
the green pigment located within the chloroplasts of plants
mesophyll
the tissue in the interior of a leaf
stomata
microscopic pores in the epidermis of leaves and stems that allow gas exchange between the environment and the interior of the plant; carbon dioxide in, oxygen out
stroma
the fluid of the chloroplast surrounding the thylakoid membrane; involved in the synthesis of organic molecules from carbon dioxide and water
thylakoid
a flattened membrane sac inside the chloroplast, used to convert light energy to chemical energy
light reactions
the steps in photosynthesis that occur on the thylakoid membranes of the chloroplast and convert solar energy to the chemical energy of ATP and NADPH
Calvin cycle
the second of two major stages in photosynthesis, involving atmospheric carbon dioxide fixation and reduction of the fixed carbon into carbohydrate
NADP+
an acceptor that temporarily stores energized electrons produced during the light reactions
photophosphorylation
the process of generating ATP from ADP and phosphate by means of a proton-motive force generated by the thylakoid membrane of the chloroplast during the light reactions of photosynthesis
carbon fixation
the incorporation of carbon from CO2 into an organic compound by an autotrophic organism (a plant, another photosynthetic organism, or a chemoautotrophic prokaryote)
wavelength
the distance between the crests of electromagnetic waves
electromagnetic spectrum
the entire spectrum of radiation ranging in wavelength from less than a nanometer to more than a kilometer
visible light
the portion of the electromagnetic spectrum detected as various colors by the human eye, ranging in wavelength from about 380 nm to about 750 nm
photon
a quantum, or discrete amount, of light energy
spectrophometer
an instrument that measures the proportions of light of different wavelengths absorbed and transmitted by a pigment solution
absorption spectrum
the range of a pigment's ability to absorb various wavelengths of light
chlorophyll a
a type of blue-green photosynthetic pigment that participates directly in the light reactions
action spectrum
a graph that depicts the relative effectiveness of different wavelengths of radiation in driving a particular process
chlorophyll b
a type of yellow-green accessory photosynthetic pigment that transfers energy to chlorophyll a
carotenoids
accessory pigments, yellow or orange, in the chloroplasts of plants that absorb violet and blue-green light- broaden the spectrum of colors that can drive photosynthesis because they absorb wavelengths of light that chlorophyll cannot
photosystem
light capturing unit located in the thylakoid membrane of the chloroplast, consisting of a reaction center surrounded by numerous light-harvesting complexes
light harvesting complex
complex of proteins associated with pigment molecules (including chlorophyll a & b and carotenoids) that captures light energy and transfers it to reaction center pigments in a photosystem
reaction center
protein complex that includes two special chlorophyll a molecules and a primary electron acceptor
primary electron acceptor
a specialized molecule sharing the reaction center with the pair of reaction-center chlorophyll a molecules; it accepts an electron from one of these two chlorophylls
photosystem 2
one of two light-capturing units in a chloroplast's thylakoid membrane; it has 2 molecules of P680 chlorophyll a at its reaction center
photosystem 1
one of two light-capturing units in a chloroplast's thylakoid membrane; it has two molecules of P700 chlorophyll a at its reaction center
noncyclic electron flow
a route of electron flow during the light reactions of photosynthesis that involves both photosystems and produces ATP, NADPH, and oxygen; net electron flow is from water to NADP+
cyclic electron flow
a route of electron flow during the light reactions of photosynthesis that involves only photosystem 1 and that produces ATP but not NADPH or oxygen
G3P
3 carbon sugar; the carbohydrate produced directly from the Calvin cycle
rubisco
the enzyme that catalyzes the first step of the Calvin cycle
photorespiration
a metabolic pathway that consumes oxygen, releases carbon dioxide, generates no ATP, and decreases photosynthetic output; generally occurs on hot, dry, bright days, when stomata close and the oxygen concentration in the leaf exceeds that of carbon dioxide
C3 plants
a plant that uses the Calvin cycle for the initial steps that incorporate CO2 into organic material, forming a 3 carbon compound as the first stable intermediate
bundle sheath cells
a type of photosynthetic cell arranged into tightly packed sheaths around the veins of a leaf
mesophyll cells
a loosely arranged photosynthetic cell located between the bundle sheath and the leaf surface
CAM
a type of metabolism in which carbon dioxide is taken in at night and incorporated into a variety of organic acids
C4 plants
a plant that prefaces the Calvin cycle with reactions that incorporate CO2 into a 4 carbon compound, the end product of which supplies CO2 for the Calvin cycle
cell division
reproduction of cells
cell cycle
life of a cell from the time it is first formed from a dividing parent cell until its own division into two cells
genome
a cell's endowment of DNA
somatic cells
all body cells except reproductive cells; 46 chromosomes
gametes
sperm cells and egg cells, reproductive cells; 23 chromosomes
chromatin
complex of DNA and associated protein molecules
sister chromatids
contain an identical DNA molecule; 2 are attached by adhesive proteins to make a chromosome
centromere
specialized region where 2 chromatids are most closely attached
mitosis
division of the nucleus
cytokinesis
division of the cytoplasm
meiosis
variation of cell division that yields nonidentical daughter cells that only have one set of chromosomes; occurs in gonads (ovaries/testes)
mitotic phase (M)
mitosis and cytokinesis- shortest part of the cell cycle
interphase
cell grows and copies its chromosomes in preparation for cell division, 90% of cell cycle
G1 phase
first gap of interphase, cell grows
S phase
synthesis of interphase, cell copies its chromosomes
G2 phase
second gap of interphase, cell continues to grow
mitotic spindle
structure consisting of fibers made of microtubules and associated proteins
centrosome
nonmembranous organelle that functions throughout the cell cycle to organize the cell's microtubules; assembles mitotic spindle
aster
radial array of short microtubules
kinetochore
structure of proteins associated with specific sections of chromosomal DNA at the centromere
metaphase plate
imaginary plate equidistant between the spindle's 2 poles, where centromeres line up
cleavage furrow
shallow groove in the cell surface near the old metaphase plate
cell plate
double membrane across the midline of a dividing plant cell, produced by vesicles derived from Golgi apparatus
binary fission
"division in half", process by which prokaryotes reproduce
origin of replication
site where the replication of a DNA molecule begins
cell cycle control system
a cyclically operating set of molecules in the cell that both triggers and coordinates key events in the cell cycle
checkpoint
critical control point where stop & go ahead signals can regulate the cycle
G0 phase
nondividing state in which a cell has left the cell cycle
cyclin
protein that gets its name from its cyclically fluctuating concentration in the cell- attaches to kinase and activates it
cyclin dependent kinases
protein kinases that are only active when attached to a particular cyclin
MPF
first discovered cdk complex; M phase promoting factor
growth factor
protein released by certain cells that stimulates other cells to divide
density dependent inhibition
crowded cells stop dividing
anchorage dependence
to divide, some cells must be attached to a substratum
transformation
process that converts a normal cell to a cancer cell
benign tumor
when abnormal cells remain at the original site; lump that isn't dangerous
malignant tumor
cancerous tumor that is invasive enough to impair the functions of one or more organs
metastasis
spread of cancer cells distant from their original site
heredity (inheritance)
transmission of traits from one generation to the next
variation
offspring differ somewhat in appearance from parents and siblings
genetics
scientific study of heredity and hereditary variation
genes
hereditary units
locus
a gene's specific location along the length of a chromosome
asexual reproduction
a single individual is the sole parent and passes copies of all its genes to its offspring
clone
a group of genetically identical individuals
sexual reproduction
two parents give rise to offspring that have unique combinations of genes inherited from the two parents
life cycle
generation to generation sequence of stages in the reproductive history of an organism, from conception to production of its own offspring
karyotype
a display of the chromosome pairs of a cell arranged by size and shape
homologous chromosomes
pairs of the same length, centromere position, and staining pattern that possess genes for the same characters at corresponding loci
sex chromosomes
X and Y chromosomes that determine an individual's sex
autosomes
chromosomes other than sex chromosomes
diploid cell
any cell with two chromosome sets
haploid cell
any cell containing a single chromosome set
fertilization
union of gametes culminating in fusion of their nuclei
zygote
fertilized egg; diploid
alternation of generations
life cycle that includes both diploid and haploid multicellular stages (plants and some algae)
sporophyte
multicellular diploid stage in alternation of generations
spores
haploid cells produced by meiosis in a sporophyte
gametophyte
multicellular haploid stage in alternation of generations
synapsis
the pairing of replicated homologous chromosomes during prophase 1 of meiosis
crossing over
the reciprocal exchange of genetic material between nonsister chromatids during prophase 1 of meiosis
tetrad
a paired set of homologous chromosomes, each composed of 2 sister chromatids; form during prophase 1 of meiosis
chiasma
the x-shaped region representing homologous chromatids that have exchanged genetic material through crossing over during meiosis
recombinant chromosomes
individual chromosomes that carry genes derived from 2 different parents
independent assortment
1st meiotic division results in each pair sorting its maternal and paternal homologoues into daughter cells independently of other pairs
character
heritable feature that varies among individuals
trait
each variant for a character
true breeding
plants that produce offspring of the same variety when they self pollinate
hybridization
mating/crossing of two true breeding varieties
P generation
true breeding parental generation
F1 generation
first filial generation of hybrid offspring
F2 generation
second filial generation resulting from interbreeding of the hybrid F1 generation
alleles
alternative versions of a gene that produce distinguishable phenotypic effects
dominant allele
allele that determines an organism's appearance
recessive allele
allele that has no noticeable affect on the organism's appearance
law of segregation
states that two alleles for a heritable character separate during gamete formation and end up in different gametes
Punnett square
diagram which predicts the allele composition of offspring from a cross between individuals of known genetic makeup
homozygous
organism has a pair of identical alleles for a character
heterozygous
organism has 2 different alleles for a gene
phenotype
an organism's traits
genotype
an organism's genetic makeup
testcross
breeding of a recessive homozygote with an organism of dominant phenotype but unknown genotype
monohybrids
organisms that are heterozygous for one character (Aa)
dihybrids
organisms that are heterozygous for both characters (AaBb)
complete dominance
phenotypes of the heterozygote and dominant homozygote are indistinguishable
incomplete dominance
phenotype is in between the phenotypes of 2 parental varieties
codominance
two alleles both affect the phenotype in separate, distinguishable ways
Tay-Sachs disease
inherited disorder in humans; brain cells are unable to metabolize certain lipids because a crucial enzyme does not work properly
epistasis
one gene at one locus alters the phenotypic expression of a gene at a second locus
quantative characters
a heritable feature that varies continuously over a range rather than in an either-or fashion
pleiotropy
the ability of a single gene to have multiple effects
polygenic inheritance
an additive effect of two or more genes on a single phenotypic character
norm of reaction
the range of phenotypic possibilities produced by a single genotype due to environmental influences
multifactorial
a phenotypic character is influenced by many factors, both genetic and environmental, that collectively influence the phenotype
pedigree
a family tree showing the occurrence of heritable characters in parents and offspring over multiple generations
carriers
heterozygotes that transmit the recessive allele to their offspring
cystic fibrosis
a human genetic disorder caused by a recessive allele for a chloride channel protein; characterized by an excessive secretion of mucus and consequent vulnerability to infection
sickle cell disease
a human genetic disease caused by a recessive allele that results in the substitution of a single amino acid in the hemoglobin protein; affects many people of African descent
achondroplasia
a form of dwarfism caused by a dominant allele
Huntington's disease
a human genetic disease caused by a dominant allele, characterized by uncontrollable body movements and degeneration of the nervous system; caused by a dominant allele that has no obvious phenotypic effect until the individual is about 35 to 45 years old
amniocentesis
a technique of prenatal diagnosis in which amniotic fluid, obtained by a needle inserted into the uterus, is analyzed to detect certain genetic and congenital defects in the fetus
chorionic villus sampling (CVS)
a technique of prenatal diagnosis in which a small sample of the fetal portion of the placenta is removed and analyzed to detect certain genetic and congenital defects in the fetus
chromosome theory of inheritance
genes are located on chromosomes and the behavior of chromosomes during meiosis accounts for inheritance patterns
wild type
an individual with the normal (most common) phenotype
linked genes
genes located close enough together on a chromosome to be usually inherited together
genetic recombination
the production of offspring with combinations of traits differing from those found in either parent
parental types
an offspring with a phenotype that matches one of the parental phenotypes
recombinant types
an offspring whose phenotype differs from that of the parents
genetic map
an ordered list of the genetic loci along a particular chromosome
linkage map
a genetic map based on recombination frequencies
map units
a unit of measurement of the distance between genes- one is equivalent to a 1% recombination frequency
cytogenetic maps
chart of a chromosome that locates genes with respect to chromosomal features
sex linked gene
a gene located on a sex chromosome
Duchenne muscular dystrophy
a human genetic disease caused by a sex-linked recessive allele; characterized by progressive weakening and a loss of muscle tissue
hemophilia
sex-linked recessive disorder defined by the absence of one or more of the proteins required for blood clotting
Barr body
a dense object lying along the inside of the nuclear envelope in female mammalian cells, representing an inactivated X chromosome
nondisjunction
an error in meiosis or mitosis, in which both members of a pair of homologous chromosomes or both sister chromatids fail to move apart properly
aneuploidy
a chromosomal aberration in which one or more chromosomes are present in extra copies or are deficient in number
trisomic
referring to a cell that has 3 copies of a particular chromosome, instead of the normal 2
monosomic
referring to a cell that has only one copy of a particular chromosome, instead of the normal two
polyploidy
a chromosomal alteration in which the organism possesses more than two complete chromosome sets
deletion
occurs when a chromosomal fragment lacking a centromere is lost; the affected chromosome is then missing certain genes
duplication
an aberration in chromosome structure due to fusion with a fragment from a homologous chromosome, such that a portion of a chromosome is duplicated
inversion
an aberration in chromosome structure resulting from reattachment in a reverse orientation of a chromosomal fragment to the chromosome from which the fragment originated
translocation
an aberration in chromosome structure resulting from attachment of a chromosomal fragment to a nonhomologous chromosome
Down syndrom
A human genetic disease caused by presence of an extra chromosome 21- aneuploid; characterized by mental retardation and heart and respiratory defects
genomic imprinting
expression of an allele in offspring depends on whether the allele is inherited from the male or female parent
T.H. Morgan
genes are located in chromosomes=protein+DNA, so which is the genetic material?
Griffith
streptococcus pneumonia bacteria- showed there was transforming material
Avery, McCarty, MacLeod
determined the transforming material was DNA, not believed
Hershey & Chase
worked with t-phage, showed that only DNA of the T2 enters the e. coli to transform it- so DNA is genetic material
Chargaff
A=T, C=G, so determined complimentary base pairing
Watson & Crick
used x-ray crystallography from Franklin, determined DNA structure
Meselson & Stahl
semiconservative model of replication- each strand of DNA is one old strand & one new strand
terminator
signal that ends transcription
downstream
direction of transcription
transcription unit
stretch of DNA that is transcribed into RNA
transcription factors
proteins that mediate binding of RNA polymerase & initiation of transcription
TATA box
promoter DNA sequence in eukaryotes
5' cap
G nucleotide on 5' end
poly A tail
A nucleotides on 3' end
UTR
untranslated regions at ends, not translated into protein
RNA splicing
removalof large portion of RNA molecule that is initially synthesized
introns
noncoding segments
exons
coding regions
snRNPs
composed of RNA & protein- recognize splice sites
spliceosome
snRNPs+protein, removes introns and joins exons
ribozymes
RNA molecules that function as enzymes
bacteriophage
virus that infects bacteria
purines
2 rings- A&G
pyramidines
1 ring- T&C
semiconservative model
double helix replicates, and each daughter molecule has one old strand and one newly made strand
conservative model
parent molecule somehow "reforms" (is conserved)
dispersive model
all 4 strands have a mix of old & new DNA
origin of replication
where replication begins & strands separate
replication fork
at end of replication bubble where new DNA strands are elongating
okazaki fragments
small sections of nucleotides on lagging strand away from replication fork
single strand binding protein
binds to unpaired DNA strands to stabilize them & keep them apart
mismatch repair
enzymes fix incorrectly paired nucleotides
nucleotide excision repair
nuclease cuts out damaged segment, nucleotides fill in by polymerase & are attached by ligase
telomeres
nucleotide sequences at end of DNA- repeated unit TTAGGG in humans, postpones erosion of genes as they shorten
gene expression
process by which DNA directs protein synthesis
primary transcript
initial RNA transcript from any gene
triplet code
genetic instructions for a polypeptide chain are written in DNA as a series of nonoverlapping, 3 nucleotide words
codons
mRNA base triplets written in 5'-3' direction
start
AUG stop: UAA/UAG/UGA
reading frame
reading symbols in the correct groupings
promoter
DNA sequence where RNA polymerase attaches & initiates transcription
alternative RNA splicing
depending on which segments are treated as exons, a single gene can encode more than one kind of polypeptide
domain
discrete structural & functional regions that make up a protein
exon shuffling
mixing & matching of exons
anticodon
nucleotide triplet which base pairs with a complementary codon on mRNA
wobble effect
relaxation of base pairing rules- 3rd base can differ
P site
holds tRNA carrying growing polypeptide
A site
holds tRNA carrying next amino acid to be added
E site
where discharged tRNAs leave the ribosome
initiation factors
proteins required to bring components together
virus
infectious particle consisting of nucleic acid enclosed in a protein coat
capsid
protein shell enclosing the viral genome
viral envelope
membranous envelope surrounding the capsid of certain viruses
bacteriophage
virus that infects bacteria
host range
limited range of host cells that a virus can infect
lytic cycle
phage reproductive cycle that culminates in death (lysing) of the host cell
virulent phage
phage that reproduces only by lytic cycle
restriction enzymes
cut up phage DNA (recognize it as foreign)
lysogenic cycle
replicates phage genome without destroying the host
temperate phages
capable of using both modes of reproducing within a bacterium
prophage
A phage genome that has been inserted into a specific site on the bacterial chromosome.
reverse transcriptase
enzyme that transcribes RNA template into DNA
retroviruses
have reverse transcriptase, go from RNADNA, ex: HIV
provirus
viral DNA that inserts into a host genome
viroids
circular RNA molecules that infect plants
prions
infectious proteins, cause degenerative brain diseases in animals
nucleoid
dense region of DNA not bounded by a membrane
transformation
alteration of a bacteria cell's genotype and phenotype by the uptake of naked, foreign DNA from the surrounding environment
transduction
phages carry bacterial genes from one host cell to another as a result of aberrations in the phage reproductive cycle
conjugation
the direct transfer of genetic material between two bacteria cells that are temporarily joined
F factor
piece of DNA that gives a bacteria cell the ability to form a sex pili
plasmid
small, circular, self replicating DNA molecule separate from the bacterial chromosome
episome
a genetic element that can replicate either as part of the bacterial chromosome or independently of it
F plasmid
plasmid form of F factor
R plasmids
resistance genes
transposable elements
part of chromosomal or plasmid DNA, "jumping genes"
insertion sequences
transposable elements, exist only in bacteria, single gene that codes for transposase
transposon
a transposable genetic element that moves within a genome by means of a DNA intermediate, longer & more complex than insertion sequences
operator
segment of DNA between promoter and enzyme coding genes- controls access of RNA polymerase to the genes
operon
operator, promoter, & genes they control (entire stretch of DNA required for enzyme production for a pathway)
repressor
protein that binds to the operator and blocks attachment of RNA polymerase to the promoter
regulatory gene
a gene that codes for a protein, such as a repressor, that controls the transcription of another gene or group of genes; far from operon it controls, expressed continuously
corepressor
small molecule that cooperates with a repressor protein to switch an operon off
inducer
specific small molecule that inactivates the repressor
activator
a protein that binds to DNA and stimulates transcription of a specific gene
chromatin
DNA protein complex
nucleosome
basic unit of DNA packing- segment of DNA wound around a protein core composed of 2 copies of each of 4 types of histone
histone
a small protein with a high proportion of positively charged amino acids that binds to the negatively charged DNA, which wraps around it
heterochromatin
highly compact chromatin that cannot be transcribed
euchromatin
less compacted chromatin; can be transcribed because it is accessible to enzymes
cell differentiation
process of specialization in form and function
differential gene expression
expression of different genes by cells with the same genome
histone acetylation
acetyl groups are attached to positively charged lysines in histone tails- loosely unwinds DNA around histones, enables transcription, turns genes on
methylation
attachment of methyl groups to cytosine- blocks transcription factors, permanent inactivation of genes
genomic imprinting
methylation permanently regulates expression of either the maternal of paternal allele of certain genes at the start of development
epigenetic inheritance
inheritance of traits transmitted by mechanisms not directly involving the nucleotide sequence
control elements
segments of noncoding DNA that help regulate transcription by binding certain proteins
transcription factors
proteins that assist RNA polymerase to initiate transcription
proximal control elements
located close to the promoter
enhancer
group of distal control elements; a DNA segment containing multiple control elements that may be located far away from the gene it regulates
activator
protein that binds to an enhancer and stimulates transcription of a gene
repressor
transcription factor that inhibits expression of a particular gene
alternative RNA splicing
different mRNA molecules are produced from the same primary transcript, depending on which segments are treated as exons/introns
miRNA
a small, single-stranded RNA molecule that binds to a complementary sequence in mRNA molecules and directs associated proteins to degrade or prevent translation of the target mRNA.
RNA interference
a technique to silence the expression of selected genes in nonmammalian organisms. The method uses synthetic double-stranded RNA molecules matching the sequence of a particular gene to trigger the breakdown of the gene's messenger RNA. due to siRNA
proteasome
giant protein complex that recognizes and destroys proteins tagged for elimination by the small protein ubiquitin
tumor viruses
cause cancer in various animals
oncogenes
cancer causing genes
proto-oncogenes
normal cellular genes that code for proteins that stimulate normal cell growth and division
tumor suppressor genes
encode proteins that prevent uncontrolled cell growth
ras protein
G protein that relays a signal from a growth factor receptor on the plasma membrane to a cascade of protein kinases- response- synthesis of protein that stimulates cell cycle
p53 protein
functions as an activator for certain genes, p21halts cell cycle by binding to cyclin dependent kinases, turns on genes involved in DNA repair, when irreparable- turns on "suicide genes" to kill cells by apoptosis
repetitive DNA
sequences that are present in multiple copies in the genome
transposons
move within genome by means of DNA intermediate
retrotransposons
move by means of an RNA intermediate
simple sequence DNA
many copies of tandemly repeated short sequences
multigene families
collections of identical or very similar genes
pseudogenes
nonfunctional nucleotide sequences similar to functional genes
polyploidy
accident in meiosis resulting in 1 or more extra sets of chromosomes
light microscope
lenses refract (bend) visible light to magnify images of specimens; up to 1,000x
magnification
ratio of an object's image to its real size
resolution
measure of the clarity of an image; minimum distance 2 points can be separated and still be distinguished as 2 separate points
organelles
subcellular structures
electron microscope
focuses a beam of electrons through the specimen or onto its surface
scanning electron microscope
electron beam scans surface; useful for the detailed study of the surface of a specimen
transmission electron microscope
electron beam is passed through the specimen, stained with heavy metals; useful to study the internal ultrastructure of cells
cell fractionation
taking cells apart to separate the major organelles from one another
ultracentrifuge
spins test tubes holding mixtures of disrupted cells
cytosol
semifluid substance in which organelles are found
nucleoid
dense region of DNA in a prokaryotic cell
cytoplasm
entire region between the nucleus and plasma membrane
plasma membrane
at the boundary of every cell; selective barrier that allows sufficient passage of oxygen, nutrients, and wastes to service the entire volume of the cell
nuclear envelope
encloses the nucleus, separating its contents from the cytoplasm
nuclear lamina
netlike array of protein filaments that maintains the shape of the nucleus by mechanically supporting the nuclear envelope
chromosomes
structures that carry DNA, the genetic information
chromatin
complex of proteins and DNA, makes up each chromosome
nucleolus
a specialized structure in the nucleus, formed from various chromosomes and active in the synthesis of ribosomes
ribosomes
particles made of ribosomal RNA and protein; organelles that carry out protein synthesis
endomembrane system
collection of membranes inside and around a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles
vesicles
sacs made of membrane
glycoproteins
proteins that have carbohydrates covalently bonded to them
transport vesicles
tiny membranous sacs in cytoplasm carrying molecules produced by the cell
phagocytosis
cells "eat" by engulfing smaller organisms or other food particles
contractile vacuole
membranous sac that pumps excess water out of some cells (freshwater protists)
tonoplast
membrane that encloses the central vacuole in a plant cell
plastids
family of closely related plant organelles that includes chloroplasts, chromoplasts, and amyloplasts
thylakoid
flattened membrane sac inside the chloroplast
granum
stack of thylakoids
stroma
fluid outside thylakoids in a chloroplast
cytoskeleton
network of fibers extending throughout the cytoplasm
cell motility
changes in cell location and limited movements of parts of the cell
motor proteins
proteins that interact with the cytoskeleton for cell motility
basal body
a eukaryotic cell organelle consisting of a 9 + 0 arrangement of microtubule triplets; may organize the microtubule assembly of a cilium or flagellum; structurally identical to a centriole
dynein
motor protein extending from one microtubule doublet to the next; "arms"
actin
globular protein that makes up microfilaments
myosin
type of protein filament that interacts with actin filaments to cause cell contraction
pseudopodia
cellular extensions of amoeba cells used in moving and feeding
cytoplasmic streaming
circular flow of cytoplasm within cells
middle lamella
thin layer between primary cell walls of adjacent plant cells rich in sticky polysaccharides called pectins
collagen
most abundant glycoprotein in the ECM of most animal cells, forms strong fibers outside the cells
proteoglycans
glycoproteins in the ECM of animal cells, rich in carbohydrate
fibronectin
glycoprotein that attaches cells to the ECM
integrins
cell surface receptor proteins that are built into the plasma membrane
plasmodesmata
channels in plant cell walls that connect adjacent cells
selective permeability
property of biological membranes that allows some substances to cross more easily than others
amphipathic molecule
a molecule that has both a hydrophilic region and a hydrophobic region
fluid mosaic model
membrane is a fluid structure with a "mosaic" of various proteins embedded in or attached to a bilayer of phospholipids
integral proteins
proteins that penetrate the hydrophobic core of the lipid bilayer
peripheral proteins
proteins that are not embedded in the lipid bilayer at all, but are appendages loosely bound to the surface of the membrane, often to the exposed parts of integral proteins
glycolipids
carbohydrates covalently bonded to lipids
glycoproteins
carbohydrates covalently bonded to proteins; most membrane carbohydrates
transport proteins
transmembrane protein that helps a certain substance or class of closely related substances cross the membrane
aquaporins
channel proteins that facilitate the passage of water molecules through the cell membrane
diffusion
the tendency for molecules of any substance to spread out evenly into the available space
concentration gradient
a substance diffuses from where it is more concentrated to where it is less concentrated, or with its-
passive transport
the diffusion of a substance across a biological membrane with its concentration gradient; requires no energy
osmosis
the diffusion of water across a selectively permeable membrane
tonicity
the ability of a solution to cause a cell to gain or lose water
isotonic
same solute concentration, no net movement of water across the plasma membrane
hypertonic
greater solute concentration, cell loses water to its environment
hypotonic
lower solute concentration, cell gains water from its environment
osmoregulation
the control of water balance
turgid
healthy, firm state for most plant cells; cell has greater solute concentration than its environment
flaccid
limp state for plant cells; cell and the surroundings are isotonic and no water enters
plasmolysis
in plant cells when cell loses water to a hypertonic environment, cytoplasm shrivels and the plasma membrane pulls away from the cell wall; lethal
facilitated diffusion
passage of molecules and ions across a biological membrane down their concentration gradients through transport proteins; requires no energy
ion channels
protein channels in the cell membrane that allow passage of a specific ion down its concentration gradient
gated channels
protein channels in the cell membrane that open or close in response to a particular stimulus
active transport
the movement of a substance across a biological membrane against its concentration gradient with the help of transport proteins; requires energy
sodium-potassium pump
transport protein in the plasma membrane of animal cells that transports sodium out of the cell and potassium into the cell against their concentration gradients
membrane potential
the charge difference between a cell's cytoplasm and the extracellular fluid due to the differential distribution of ions
electrochemical gradient
diffusion gradient of an ion, combination of concentration gradient and electrical force- inside of cell is negative compared to the outside, so the membrane potential favors the passive transport of cations into the cell and anions out of the cell
electrogenic pump
ion transport protein that generates voltage across a membrane
cotransport
the coupling of the "downhill" diffusion of one substance to the "uphill" transport of another against its own concentration gradient
exocytosis
the cellular secretion of macromolecules by the fusion of vesicles with the plasma membrane
endocytosis
the cellular uptake of macromolecules and particulate substances by localized regions of the plasma membrane that surround the substance and pinch off to form an intracellular vesicle
ligand
any molecule that binds specifically to a receptor site of another molecule
signal transduction pathway
the process by which a signal on a cell's surface is converted into a specific cellular response in a series of steps
local regulator
a chemical messenger that influences cells in the vicinity
hormones
long distance signaling; molecules are released into vessels of the circulatory system, by which they travel to target cells in other parts of the body
reception
the target cell's detection of a signal molecule coming from outside the cell; chemical signal binds to a receptor protein located at the cell's surface or inside the cell
transduction
the binding of the signal molecule changes the receptor protein in some way, and the signal is converted to a form that can bring about a specific cellular response
response
the transduced signal finally triggers a specific cellular response
protein kinase
the general name for an enzyme that transfers phosphate groups from ATP to a protein
protein phosphatases
enzymes that can rapidly remove phosphate groups from proteins by dephosphorylation
second messengers
small, nonprotein, water-soluble molecules or ions that relay a signal to a cell's interior in response to a signal received by a signal receptor protein
adenylyl cyclase
enzyme embedded in the plasma membrane that converts ATP to cAMP in response to an extracellular signal
IP3 (inositol trisphosphate)
second messenger that functions as an intermediate between certain nonsteroid hormones and a third messenger, a rise in cytoplasmic Ca 2+ concentration
DAG (diacylglycerol)
second messenger produced by the cleavage of a certain kind of phospholipid in the plasma membrane
scaffolding proteins
large relay proteins to which several other relay proteins are simultaneously attached
matter
anything that takes up space and has mass
element
substance that cannot be broken down to other substances by chemical reactions- 92
compound
substance consisting of two or more different elements combined in a fixed ratio
trace elements
element required by an organism in only minute quantities ex: iron, iodine
atom
smallest unit of matter that still retains the properties of an element
neutron
electrically neutral particle found in the nucleus of an atom
proton
subatomic particle with a single positive electrical charge, found in the nucleus of an atom
electron
subatomic particle with a single negative charge; one or more move around the nucleus of an atom
atomic nucleus
an atom's central core containing protons and neutrons
dalton
unit of measurement of mass for atoms and subatomic particles
atomic number
number of protons in the nucleus of an atom, unique for each element and designated by a subscript to the left of the elemental symbol
mass number
sum of the number of protons and neutrons in an atom's nucleus
atomic mass
total mass of an atom, in grams of one mole of the atom
isotope
one of several atomic forms of an element, each containing a different number of neutrons and thus differing in atomic mass
radioactive isotope
an isotope that is unstable; the nucleus decays spontaneously, giving off detectable particles and energy
energy
the capacity to cause change by doing work
potential energy
energy that matter possesses because of its location or structure
energy levels
different states of potential energy that electrons have in an atom
electron shells
energy level represented as the distance of an electron from the nucleus of an atom- most potential energy in the shell farthest from the nucleus
valence electrons
electrons in the outermost electron shell
valence shell
outermost energy shell of an atom, containing the valance electrons involved in the chemical reactions of that atom
orbital
the three-dimensional space where an electron is found 90% of the time
chemical bond
an attraction between two atoms, resulting from a sharing of outer-shell electrons or the presence of opposite charges on the atoms; the bonded atoms gain complete outer electron shells
covalent bond
sharing of a pair of valence electrons by two atoms
molecule
2 or more atoms held together by covalent bonds
single bond
pair of shared electrons- notation: -
structural formula
type of molecular notation in which the constituent atoms are joined by lines representing covalent bonds
molecular formula
type of molecular notation indicating only the quantity of the constituent atoms
double bond
2 pairs of shared electrons- notation: =
valence
bonding capacity of an atom; number of unpaired electrons in the atom's outermost shell
electronegativity
attraction of a particular kind of atom for the electrons of a covalent bond
nonpolar covalent bond
electrons are equally electronegative and electrons are shared equally
polar covalent bond
one atom is more electronegative than the other, and electrons are not shared equally
ion
charged atom or molecule
cation
positive ion
anion
negatively charged ion
ionic bond
attraction between oppositely charged ions; transfer electrons
salts
compounds formed by ionic bonds
hydrogen bond
type of weak chemical bond formed when the slightly positive hydrogen atom of a polar covalent bond in one molecule is attracted to the slightly negative atom of a polar covalent bond in another molecule
van der Waals interactions
weak attractions between molecules or parts of molecules that are brought about by localized charge fluctuations
chemical reactions
the making and breaking of chemical bonds, leading to changes in the composition of matter
reactant
starting material in a chemical reaction
product
ending material in a chemical reaction
chemical equilibrium
in a reversible chemical reaction, the point at which the reactions offset one another exactly- the rate of the forward reaction equals the rate of the reverse reaction
polar molecule
a molecule (ex, water) with opposite charges on opposite sides
cohesion
the binding together of like molecules by hydrogen bonds
adhesion
attraction (clinging) of one substance to another
surface tension
a measure of how difficult it is to stretch or break the surface of a liquid
kinetic energy
energy of motion
heat
measure of the total amount of kinetic energy due to molecular motion in a body of matter
temperature
measure of the intensity of heat due to the average kinetic energy of themolecules
calorie
amount of heat it takes to raise the temperature of 1 g of water by 1 degree C
joule
measure of energy, 0.239 calories
specific heat
amount of heat that must be absorbed or lost for 1 g to change its temperature by 1 degree C
heat of vaporization
quantity of heat a liquid must absorb for 1 g of it to be converted from the liquid to the gaseous state
evaporative cooling
as a liquid evaporates, the surface of the liquid that remains behind cools down
solution
a liquid that is a completely homogeneous mixture of two or more substances
solvent
dissolving agent of a solution
solute
substance that is dissolved in a solution
aqueous solution
solution in which water is the solvent
hydration shell
the sphere of water molecules around each dissolved ion
hydrophilic
a substance that has an affinity for water, ionic/polar
colloid
a stable suspension of fine particles in a liquid
hydrophobic
a substance that repels water, nonionic/nonpolar
molecular mass
the sum of the masses of all the atoms in a molecule
mole
(avogadro's number) 6.02 x 10^23 molecules
molarity
number of moles of solute per liter of solution
hydrogen ion
single proton with a charge of +1 (H+)
hydroxide ion
water molecule that has lost a proton and has a charge of -1 (OH-)
acid
a substance that increases the hydrogen ion concentration of a solution
base
a substance that reduces the hydrogen ion concentration of a solution
pH
negative logarithm of the hydrogen ion concentration
buffer
a substance that minimizes changes in the concentration of H+ and OH- in a solution
acid precipitation
rain, snow, or fog with a pH lower or more acidic than pH 5.6
organic chemistry
the branch of chemistry that specializes in the study of carbon compounds
hydrocarbons
organic molecules consisting only of carbon and hydrogen
isomers
compounds that have the same numbers of atoms of the same elements but different structures and hence different properties
structural isomers
isomers that differ in the covalent arrangements of their atoms
geometric isomers
isomers that differ in spatial arrangements of their atoms
enantiomers
isomers that are mirror images of each other
functional groups
components of organic molecules that are most commonly involved in chemical reactions
adenosine triphosphate
primary energy-transferring molecule in the cell: an organic molecule attached to a string of 3 phosphate groups
macromolecule
a giant molecule formed by the joining of smaller molecules, usually by a condensation reaction
polymer
long molecule consisting of many similar or identical building blocks linked by covalent bonds
monomers
repeating units that serve as the building blocks of a polymer
condensation/dehydration reaction
a reaction in which 2 molecules are covalently bonded to each other through loss of a water molecule
hydrolysis
a chemical process that lyses, or splits, molecules by the addition of water
carbohydrates
sugars and the polymers of sugars
monosacccharides
the simplest carbohydrate, "simple sugars", molecular formulas are multiples of CH2O
disaccharide
2 monosaccharides joined by a glycosidic linkage
glycosidic linkage
covalent bond formed between 2 monosaccharides by a dehydration reaction
starch
a polymer consisting entirely of glucose monomers; storage polysaccharide of plants
glycogen
polymer of glucose that is like amylopectin but more extensively branched; stored food
cellulose
polysaccharide; major component of the tough walls that enclose plant cells
chitin
carbohydrate used by arthropods to build their exoskeletons
lipids
fats, phospholipids, steroids; insoluble in water
fat
constructed from 2 kinds of smaller molecules- glycerol and fatty acids
fatty acid
long carbon skeleton with a carboxyl group at one end attached to a hydrocarbon chain
triacylglycerol
3 fatty acids linked to 1 glycerol molecule
saturated fatty acid
fatty acid in which all carbons in the hydrocarbon tail are connected by single bonds, thus maximizing the number of hydrogen atoms that can attach to the carbon skeleton
unsaturated fatty acid
fatty acid possessing one or more double bonds between the carbons in the hydrocarbon tail. such bonding reduces the number of hydrogen atoms attached to the carbon skeleton
phospholipid
molecule that is a constituent of the inner bilayer of biological membranes, having a polar, hydrophilic head and a nonpolar, hydrophobic tail
steroid
a lipid characterized by a carbon skeleton consisting of 4 fused rings
cholesterol
a common component of animal cell membranes and the precursor from which other steroids are synthesized
catalysts
chemical agents that selectively speed up chemical reactions in the cell without being consumed by the reaction
polypeptide
polymers of amino acids linked by peptide bonds
protein
one or more polypeptides folded and coiled into specific conformations
amino acids
organic molecules possessing both carboxyl and amino groups
peptide bond
covalent bond between 2 amino acid units, formed by a dehydration reaction
denaturation
a process by which a protein unravels and loses its native conformation, thereby becoming biologically inactive
chaperonins
protein molecules that assist the proper folding of other proteins
x-ray crystallography
a technique often used to study the 3 dimensional structure of a protein
gene
discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA
polynucleotides
polymer consisting of many nucleotide monomers; serves as a blueprint for proteins and, through the actions of proteins, for all cellular activityes
nucleotide
nitrogenous base, pentose sugar, and a phosphate group
pyrimidine
nitrogenous base with a 6 membered ring of carbon and nitrogen atoms; C, T, U
purine
nitrogenous base with a 6 membered carbon ring fused to a five membered ring; A, G
metabolism
the totality of an organism's chemical reactions
metabolic pathway
series of chemical reactions that either builds a complex molecule or breaks it down
anabolic pathway
metabolic pathway that consumes energy to synthesize a complex molecule from simpler compounds
catabolic pathway
metabolic pathway that releases energy by breaking down complex molecules to simpler compounds
bioenergetics
the study of how organisms manage their energy resources
chemical energy
potential energy available for release in a chemical reaction
thermodynamics
the study of the energy transformations that occur in a collection of matter
first law of thermodynamics
energy can be transferred and transformed, but it cannot be created or destroyed
entropy
a quantitative measure of disorder or randomness
second law of thermodynamics
every energy transfer or transformation increases the entropy of the universe
free energy
a measure of the portion of a system's energy that can perform work when temperature and pressure are uniform throughout the system
exergonic reaction
a spontaneous chemical reaction in which there is a net release of free energy
endergonic reaction
a spontaneous chemical reaction that absorbs free energy from its surroundings
energy coupling
the use of an exergonic process to drive an endergonic one
phosphorylated
a molecule that recieves a phosphate group is said to be:
enzyme
catalytic protein
activation energy
the initial investment of energy for starting a reaction
substrate
the reactant an enzyme acts on
enzyme substrate complex
temporary complex formed when an enzyme binds to its substrate molecules
active site
the specific portion of an enzyme that attaches to the substrate by means of weak chemical bonds
induced fit
change in shape of the active site of an enzyme so that it binds more snugly to the substrate
cofactors
nonprotein "helpers" for an enzyme's catalytic activity
conenzymes
organic molecules serving as cofactors
competitive inhibitors
reduce the activity of an enzyme by entering the active site in place of the substrate whose structure it mimics
noncompetitive inhibitors
reduce the activity of an enzyme by binding to a location remote from the active site, changing its conformation so that is no longer binds to the substrate
allosteric regulation
the binding of a molecule to a protein that affects the function of the protein at a different site
cooperativity
substrate molecule causing induced fit in one subunit triggers the same favorable conformation change in all the other subunits of the enzyme; amplifies the response of enzymes to substrates
feedback inhibition
a metabolic pathway is switched off by the inhibitory binding of its end product to an enzyme that acts early in the pathway
ecology
study of interactions between organisms and the environment
abiotic
nonliving- temperature, light, water, nutrients
biotic
living
biota
all organisms
orgismal ecology
how an organism's physiology and behavior meet the challenges posed by the environment
population
a group of individuals of the same species living in a particular geographic area
population ecology
factors that affect how many individuals of a particular species live in an area
community
all organisms of all species that inhabit a particular area
community ecology
how interactions such as predation, competition, and disease, as well as abiotic factors such as disturbance, affect community structure and organization
ecosystem
all abiotic factors in addition to the entire community of species that exist in a certain area
ecosystem ecology
study of energy flow and chemical cycling among biotic/abiotic components
landscape ecology
how arrays of ecosystems are arranged in a geographic region
patchiness
localized variation in environmental conditions within an ecosystem
biosphere
global ecosystem- sum of all ecosystems
precautionary principle
"an ounce of prevention is worth a pound of cure"
dispersal
movement of individuals away from high population density or from their area of origin
species transplants
intentional or accidental transplants of a species to areas where it was previously absent- must survive and reproduce to be successful (potential range>actual range)
habitat selection
behavior limits distribution- species doesn't occupy all of potential range
biotic factors
food resources, predation, parasitism, disease, competition, absence of other species
abiotic factors
temperature, water, sunlight, wind, rocks and soil
climate
the prevailing weather conditions in a particular area
macroclimate
patterns on global, regional, and local levels
microclimate
very fine patterns- ex; under a fallen log
turnover
semiannual mixing of lake waters as a result of changing temperature profiles, brings nutrient rich water to top in spring & fall
biomes
major types of ecological associations that occupy broad geographic regions of land or water
photic zone
the narrow top of the ocean, light permeates sufficiently for photosynthesis to occur
aphotic zone
below photic zone, not enough light permeates for photosynthesis to occur
benthic zone
substrate of sand and sediments (ooze); bottom surface of an aquatic environment.
benthos
communities of organisms that occupy benthic zones
detritus
dead organic matter- food for benthos
thermocline
rapid temperature change between warm upper layer and cold deeper waters
climograph
plot of temperature and precipitation in a particular region
canopy
uppermost layer of a terrestrial biome
ecotone
area of intergradations between biomes
learning
modification of behavior based on specific experiences
habituation
loss of responsiveness to stimuli that convey little to no information
spatial learning
modification of behavior based on experience with the spatial structure of the environment, including the locations of nest sites, hazards, food, and prospective mates
landmark
location indicator
cognitive map
internal representation of the spatial relationships between objects in an animal's surroundings
associative learning
the ability of many animals to associate one feature of the environment (a stimulus, such as color) with another (bad taste)
classical conditioning
arbitrary stimulus is associated with a reward of punishment
operant conditioning
animal learns to associate one of its own behaviors with a reward or punishment and then tends to repeat or avoid that behavior (trial and error learning)
cognition
ability of an animal's nervous system to perceive, store, process, and use information gathered by sensory receptors
cognitive ethology
study of animal cognition
foraging
behavior associated with recognizing, searching for, capturing, and consuming food
optimal foraging theory
compromise between benefits of nutrition and costs of obtaining food
promiscuous mating
no strong pair-bonds or lasting relationships
monogamous
a type of relationship in which one male mates with just one female
polygamous
a type of relationship in which an individual of one sex mates with several of the other
polygyny
polygamous mating system involving one male and many females
polyandry
polygamous mating system involving one female and many males
agnostic behavior
ritualized contest that determines which competitor gains access to a resource (food/mates)
game theory
evaluates alternative strategies in situations where the outcome depends not only on each individual's strategy but also on the strategies on other individuals
altruism
selflessness; behaving in ways that reduce individual fitness but increase fitness of others
inclusive fitness
total effect an individual has on proliferating its genes by producing its own offspring and by providing aid to enable other close relatives (that share genes) to produce offspring
coefficient of relatedness
probability that if two individuals share a common parent or ancestor, a particular gene present in the individual will also be present in the second individual
hamilton's rule
natural selection favors altruism when the benefit to the recipient multiplied by the coefficient of relatedness exceeds the cost to the altruist (rB>C)
kin selection
natural selection that favors altruistic behavior by enhancing reproductive success of relatives
reciprocal altruism
altruistic behavior between two unrelated individuals, where the current altruist will benefit in the future when the current beneficiary reciprocates
social learning
learning through observing others
culture
system of information transfer through social learning or teaching that influences the behavior of individuals in a population
mate choice copying
individuals in a population copy the mate choice of others
sociobiology
certain behavioral characteristics exist because they are expressions of genes that have been perpetuated by natural selection
population
group of individuals of a single species living in the same general area
density
number of individuals per unit area or volume
dispersion
pattern of spacing among individuals within the boundaries of the population
immigration
influx of new individuals from other areas
emigration
movement of individuals out of a population
territoriality
defense of a bounded physical space against encroachment by other individuals
demography
study of the vital statistics of populations and how they change over time
life tables
age specific summaries of the survival pattern of a population
cohort
group of individuals of the same age
survivorship curve
plot of the proportion or numbers in a cohort still alive at each age
reproductive table
age specific summary of the reproductive rates in a population
life history
traits that affect an organism's schedule of reproduction and survival
big-bang reproduction/semelparity
adults have a single reproductive opportunity to produce large numbers of offspring
repeated reproduction/iteroparity
adults produce large numbers of offspring over many years
zero population growth (ZPG)
per capita birth and death rates are equal (r=0)
exponential population growth
geometric increase of a population as it grows in an ideal, unlimited environment; ∆N/∆t=r_max N
intrinsic rate of increase
maximum rate of increase for the species (rmax)
carrying capacity
(K) maximum population size that a particular environment can support
logistic population growth
per capita rate of increase declines as carrying capacity is reached ∆N/∆t=r_max N ((K-N))/K
k-selection
density dependent selection
r-selection
density independent selection
density independent
birth or death rate that does not change with population density
density dependent
death rate that rises as population density rises
population dynamics
complex interactions between biotic and abiotic factors that cause variation in population size
metapopulation
linked population groups
demographic transition
movement from high birth rates & high death rates to low birth rates & low death rates
age structure
relative number of individuals at each age
infant mortality
number of infant deaths per 1,000 live births
life expectancy at birth
predicted average length of life at birth
ecological footprint
aggregate land and water area appropriated by each nation to produce all the resources it consumes and to absorb all the waste it generates
ecological capacity
actual resource base of each country