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GED

Terms in this set (286)

conditions for natural selection
variation, differences in survival and reproduction, and heritability
evolution
genetic change in a population over time
Natural selection acts on
phenotypes not genotypes
Tiktaalik roseae
"missing link" thought to be a transitional form between fish and tetrapods
"bad design"
left recurrent laryngeal nerve
Biogeography
study of the distribution of organisms around the world
Biogeography example
species similar to those on nearest land mass
convergent evolution
Process by which unrelated organisms independently evolve similarities when adapting to similar environments
convergent evolution example
cacti and euphorbia, bat and bird wings
Marsuplial travel
marsupials walked from South Africa through Antarctica to Australia after separation of Africa from South America (fossils found in Antarctica but not in Africa)
molecular clock
Model that uses DNA comparisons to estimate the length of time that two species have been evolving independently
genetic sequence data
allows to establish the ancestry and relationship between species
pseudogenes
genes that have become inactivated by mutations
olfactory genes in whales
became pseudogenes (through mutations), because whales went back to water
lactase persistence
the ability to produce the enzyme lactase after age of 5
genetic code is redundant
some mutations won't cause a change in the amino acid sequence
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.
where and when life arose
proton gradients around alkaline hydrothermal vents - "Lost City", 3.8 bilion years ago
LUCA
last universal common ancestor
RNA world hypothesis
earliest organisms probably used RNA as enzymes which could copy themselves, at first probably RNA replicated in small pores in the thermal vents
cell
needed to protect the fragile RNA and DNA chains
key phases in evolution of life
prebiotic chemistry - pre RNA world - RNA world - first DNA protein life - diversification of life
eukaryogenesis
happened around 2 bilion years ago
archean engulfed a heterothropic eubacterium which eventually became mitochondrium
how endosymbiosis allowed more complex life
mitochondria provide enough energy to provide for a complex life forms
Edicaran biota
An early group of macroscopic, soft-bodied, multicellular eukaryotes known from fossils that range in age from 635 million to 535 million years old.
Cambrian explosion
A burst of evolutionary origins when most of the major body plans of animals appeared in a relatively brief time in geologic history; recorded in the fossil record about 545 to 525 million years ago.
Causes of Cambrian Explosion
dissolved oxygen in the oceans
geographical changes
sea level changes - aboundance of trace metals to make exoskeletons
increase in zooplankton
mass extinction
event in which many types of living things become extinct at the same time
mass extinction consequences
dissapearance of dinosaurs - ecological space for birds and mammals
mass extinction (end of Permian) causes
rapid climate change caused by multiple events (volcanism, tectonic plates, asteroid)
molecular phylogenies
all support the evidence for evolution
biological species concept
Species is a group of populations whose members have the potential to produce fertile offspring.
allopatric speciation
The formation of new species in populations that are geographically isolated from one another.
sympatric speciation
The formation of new species in populations that live in the same geographic area
genetic drift
A change in the allele frequency of a population as a result of chance events rather than natural selection.
allopolyploid speciation
species formation through hybridization between members of evolutionary lineages with strongly differentiated genomes followed by chromosomal doubling, tripling, etc.
Blackcaps evolution
Show assortative mating - birds which overwinter in Spain tend to mate with the birds which overwintered in Spain rather than with the ones which stayed in the UK.
Show rapid genetic change
Probably due to arival time on breeding grounds
crow evolution
assortative mating possible with regard to colour
mating isolation
potential mates come into contact but do not mate
premating barriers
habitat isolation
temporal isolation
behavioural isolation
Postmating Barriers
(Prezygotic)
mechanical isolation (wrong side of shell in snails)
gametic isolation
postzygotic barriers
reduced hybrid viability, reduced hybrid fertility, hybrid breakdown
Polyploidy
condition in which an organism has extra sets of chromosomes
inversion mutation
Mutation in which a chromosome piece reattaches to original chromosome but in reverse orientation
hybrid zones over time
reinforcement, fusion, stability
reinfocement of isolation
The process by which natural selection increases reproductive isolation
If the hybrids had lower fitness than either parental form, selection would act to increase the reproductive isolation because each form would do better not to mate with the other and form the disadvantageous hybrids.
Fitness
Ability of an organism to survive and reproduce in its environment
sickle cell disease
Individuals who are homozygous for the gene controlling hemoglobin S. The disease is characterized by the destruction of red blood cells and by episodic blocking of blood vessels by the adherence of sickle cells to the vascular endothelium.
heterozygote advantage
Greater reproductive success of heterozygous individuals compared to homozygotes; tends to preserve variation in gene pools (sickle cell disease - more persistent to malaria)
what is selected
individuals who express phenotypes which are at least partly determined by genes
sexual selection
A form of natural selection in which individuals with certain inherited characteristics are more likely than other individuals to obtain mates.
altruism
the behaviour of an animal that benefits another on its own expense
kin selection
the process by which evolution selects for individuals who cooperate with their relatives
inclusive fitness
direct fitness + indirect fitness (fitness of related offspring)
Hamilton's rule
natural selection of genes that favour social actions via the sharing of these genes between the performer and the recipient
Hamilton's Rule Equation
rB>C
c - cost
b - benefit
r - relatedness
altruistic behaviours are particularly likely to occur when
r is high (social insects)
Hymenoptera
ants, bees, wasps
Haplodiploidy
Females are diploid, males develop from unfertilized eggs and are haploid. Found in Bees, Ants, and Wasps
an ant is more closely related to
her sister than her offspring
Eusociality
Altruism in social groups that have sterile individuals
how many genes code for protein
3%
How many genes are regulatory genes?
10%
How many genes are junk DNA
85%
Transposons
(jumping genes) short strands of DNA capable of moving from one location to another within a cell's genetic material
Retrotransposons
Transposable elements that move within a genome by means of an RNA intermediate, a transcript of the retrotransposon DNA; remnants of retroviruses
movement of transposons
can result in mutations
involved in cancer and development disorders
methylation
can prevent transposition thus preventing a mutation
there is a conflict between transposones and the host
anti-freezer glycoproteins and mammalian placenta
arose by trasposone translocation
horizontal gene transfer
The transfer of genes from one genome to another through mechanisms such as transposable elements, plasmid exchange, viral activity, and perhaps fusions of different organisms,
can lead to adaptation
pea aphids are normally green
they aquired genes participating in carotenoid biosynthesis from fungus
natural selection and adaptation in humans
darker skin colour
Bajau people in SE Asia - adapted to diving
EPASI genes in tibetans
Neanderthals
Homo sapiens neanderthalensis, a European variant of Homo sapiens that died out about 25,000 years ago.
Denisovans
A newly discovered group of archaic Homo sapiens from southern Siberia dated to between 30,000 and 50,000 years ago.
Homo sapiens dispersal
200,000 ya Africa -> Greece and China (died out)
70,000 ya Africa -> rest of the world
was there only one dispersal event in human history?
probably many dispersal events led by climate change but only one led to couquering the whole world
When did humans appear?
300,000 ya
What decreases with distance from East Africa?
heterozygosity (genetic variation)
bottelneck effect
12,000 people survived climate change humans almost died out
Which human populations have the HIGHEST levels of genetic variation?
ancestral populations (South Africa)
connection between homo sapiens and homo neandethalis
cousins rather than ancestors
Denisovans and Neanderthals interbred with humans (examples)
EPASI gene in Tibetans (Denisovans)
Immunity response and skin colour (Neanderthals)
3% of differences in the DNA between Neanderthals and Homo sapiens
Anthropocene
the modern geological era during which humans have dramatically affected the environment
How do humans affect the earth?
rising CO2
rising sea level
mass extinction
massive pollution of the environment
What makes us human?
cooperation and how we run our societies
Polyandry
One female, several males.
gene flow
movement of alleles from one population to another
founder effect
change in allele frequencies as a result of the migration of a small subgroup of a population
Overdominance
heterozygote advantage
Microevolution
Change in allele frequencies in a population over generations.
macroevolution
microevolution + chance events
allele frequency
number of alleles of one type / total number of alleles
genotype frequency
# of individuals with a particular genotype in a population/ total # of individuals in a population
Hardy-Weinberg equilibrium
condition that occurs when the frequency of alleles in a particular gene pool remain constant over time
Hardy-Weinberg equation
p^2 + 2pq + q^2 = 1
where p and q are the allele frequencies
once the H-W equilibrium is reached it will stay the same if
population size is large
mating is random
no migration
no selection
no mutation* (always occur)
genotype frequencies from allele frequencies
compare observed and expected genotype frequencies (Chi squared test)
Expected (H-W)
f(RR) = p^2
f(Rr) = 2pq
f(rr) = q^2
Observed (H-W)
#of individuals of one genotype / # of all individuals in the population
factors leading to changes in allele and genotype frequency
genetic drift (low population size)
non-random mating
migration/gene flow
selection
the paradox of variation
evolution requires variation, but natural selection eliminates variation
how is genetic variation preserved
balancing selection
heterozygote advantage
frequency dependent slection
most genetic variation is neutral
Mitosis
cell division which results in the production of two identical diploid daughter cells
Meiosis
Cell division that produces reproductive cells in sexually reproducing organisms, consists of 2 divisions
cell cycle
period between the birth of cell and it's divition into daughter cells
what phase do meiosis and mitosis start in the cell cycle?
G2 phase with replicated chromosomes
When does crossing over occur?
prophase I of meiosis
When does independent assortment occur?
Metaphase I of meiosis
monohybrid cross
A cross between individuals that involves one pair of contrasting traits
Monohybrid cross ratio
one gene with two alleles
3:1 phenotypic ratio
Law of segregation
dihybrid cross
Cross or mating between organisms involving two pairs of contrasting traits (AABB x aabb)
dihybrid cross ratio
two genes
9:3:3:1 ratio
independent assortment
point mutation
gene mutation in which a single base pair in DNA has been changed
silent mutation
A mutation that changes a single nucleotide, but does not change the amino acid created.
nonsense mutation
A mutation that changes an amino acid codon to one of the three stop codons, resulting in a shorter and usually nonfunctional protein.
missense mutation (conservative)
altered codon specifies a chemically similar amino acid
missense mutation (nonconservative)
altered codon specifies a chemically dissimilar amino acid (most severe effects)
wild type (WT)
genotype or phenotype of natural populations or standard laboratory strains (functional protein)
loss of function
non-functional protein (most of mutations)
gain of function mutation
protein with new or enchanced function (less common)
LOF alleles are
recessive
for most genes 50% of the normal amount of gene product is sufficient for WT function
GOF alleles are
dominant
incomplete dominance
heterozygote phenotype is intermediate between the two homozygote phenotypes (scale of dominance)
example of incomplete dominance
red x white = pink
familial hypercholesterolaemia (mutation of gene encoding LDL receptors - heterozygote shows mild disease)
co-dominance
heterozygous genotype that equally expresses the traits from both alleles (ABO blood groups - AB)
multiple alleles
three or more forms of a gene that code for a single trait (mice coat colour A>a^t> a)
pleiotropy
one gene may influence more than one trait
lethal alleles
causes skewed phenotypic ratios
lethal allele example
yellow allele in mouse - dominant for coat colour, however recessive for lethality - homozygous yellow mice are never born (1:2)
lethal allele in humans
Achondroplasis - GOF mutation in a growth factor receptor (FGRF3)
Epistasis
A type of gene interaction in which one gene alters the phenotypic effects of another gene that is independently inherited.
what does it mean that albino gene is epistatic to all other coat colours?
albino masks the effect of differenct genes determinig the colour (9:4:3)
why is albino allele (c) epistatic to all other coat colour genes?
albino allele is recessive LOF mutation in the gene coding fr the enzyme tyrosinase required for melanin synthesis
dominant epistasis
when the dominant allele of one gene masks the effects of either allele of the second gene (12:3:1)
Dominant LOF mutation in mice
transmembrane growth factor required for loss of proliferation and migration of melanocytes -> white colour
penetrance
The percentage of individuals with a particular genotype that actually displays the phenotype associated with the genotype.
expressivity
the degree to which a trait is expressed
why don't individuals with the same genotype express the same phenotype?
due to differences in penetrance and expressivity
incomplete penetrance example
BRCA1 gene mutations do not always result in breast or ovarian cancer (30-40% of women won't get the cancer)
variable expressivity (example)
variable colour in mice caused by insertion of a transposable element in the promoter region of the agouti gene
modifier genes
enhance or dilute the effects of other genes
modifier genes example
heterozygosity for mutations in PRPH2 and ROM1 genes - single heterozygote doesn't get the disease (retinitis pigmentosa) digenicheritance
epigenetics
inherited changes in gene functions not caused by mutation but by environmental factors
epigenetic tags
DNA methylation and histone modification - alter chromatin structure, can be passed on to daughter cells
paternal imprinting
The expression of a gene only when inherited from the mother, because the allele of the gene inherited from the father is inactive due to methylation in the course of gamete formation.
maternal imprinting
Alleles inherited from the father are not silenced, while those inherited from mother are
Prader-Willi Syndrome
deletion is of paternal origin (chromosome 15) caused by lack of several maternally imprinted genes
Angelman Syndrome
deletion of maternal origin caused by lack of paternally imprinted UBE3A gene
Why does imprinting exist
affects a limited number of genes
many imprinted genes are involved in foetal growth (maternal suppress, paternal promote)
kinship/paternal conflict theory
conflict between the 'intersts' of maternal and paternal genes in the foetus
pseudoautosomal region
small region on the X and Y chromosomes that contains homologous gene sequences
Aneuploidy
Abnormal number of chromosomes.
SRY region of Y chromosome
required to determine maleness
sex determination in birds
ZZ male, ZW female
gynandromorph
Individual organism that is a mosaic for the sex chromosomes, possessing tissues with different sex-chromosome constitutions.
Evolution of sex chromosomes
autosomes mutated to have SRY and accumulated male advantage genes
deletion of genes not needed for male advantage
sex-linked inheritance
Inheritance of a genetic trait located on the sex chromosomes (usually X)
Hemizygosity
only one copy of a gene or DNA sequence is present in diploid cell
males are hemizygous for most genes on sex chromosomes
Examples of X-linked disorders
Duchenne muscular dystrophy, hemophilia,
colour blindness,
Barr's body
inactivated, highly condensed X chromosome in females
can you get a male tortoiseshell cat?
yes if the male cat has more than one X chromosome (XXY)
physical gene map
shows distance between genes or DNA markers based on the direct measurement of DNA
cytogenic map
indicates the positions of genes with respect to cytogenic markers (e.g. banding patterns) that are visible on the chromosome after staining
linkage maps
show relative position of genes or markers on a chromosome based on meiotic recombination frequencies (centiMorgan cM)
centiMorgan (cM)
A unit of distance between genes on chromosomes based on the frequency of crossing over
frequency of recombinant gametes
half the frequency of crossing over (chiasma frequency)
because a single crossover affects only 2 of 4 chromatids;
distance increases 2x& the frequency increses 2x
50% recombinant gametes
genes are either on different chromosomes or far apart on the same chromosome
less than 50% recombinant gametes
genes are linked on the same chromosome, the smaller the recombinant frequency the closer they are
recombination frequency (RF) = genetic distance (equation)
# of recombinant progeny x100/ total number of progeny
10% of RF is how many cM
10 cM
genetic linkage
alleles of genes on the same chromosome will segregate together
linkage mapping principles
crossing over occurs at random along each chromosome,
the frequency of crossing-over between two gene loci is proportional to the physical distance between them on the chromosome
Haplotype
particular combination of SNPs in a small region of a chromosome
autosomal recessive disorder phenotype on a pedigree chart can
skip generations
both parents must be carriers to transmit
affects both genders equally
autosomal dominant disorder phenotype on a pedigree chart
appears in every generation and affects both genders equally;
somtimes homozygous mutant is lethal
X-linked recessive disorder phenotype on a pedigree chart
more males are affected
X-linked recessive disorders can be transmitted through
unaffected carrier female,
hemizygous affected male,
affected female
transmission through unaffected carrier female (X linked recessive)
half of sons predicted to be affected and half of daughters predicted to be carriers (but none affected)
transmission through hemizygous affected male (X linked recessive)
none of the children are affected but all his daughters are carriers
transmission thorough affected female (X linked recessive)
all sons will be affected and all daughters will be carriers
X linked dominant disorders
affected males pass the condition to all daughters but none of their sons,
affected heterozygous female with unaffected male partners passes the condition to half of her offspring
STRs
Short Tandem Repeats, regions of a DNA molecule that contain short segments consisting of three to seven repeating base pairs, highly variable between individuals
forensic analysis using STRs
PCR is used to amplify 10 STRs and a gender DNA marker, separated by electrophoresis to give a DNA profile
SNPs
single nucleotide polymorphisms (differences) between individuals (1 nucelotide difference in every 1000 nucleotides)
positional cloning of the disease gene
select candidate genes in the region of the chromosome,
look for disease-associated mutations in each candidate gene
cause of non-disjunction
premature loss of cohesion gives two univalents that segregate independently
mosaicism (Down Syndrome)
1% of all cases
diagnosed when there is a mixture of two types of cells (46 or 47 chromosomes)
often fewer symptoms
Translocation (Down Syndrome)
additional full or partial copy of 21 chromosome attachest to another chromosome (14)
Turner Syndrome
XO (45,X) sterile females, short stature, learing difficulties
Klinefelter syndrome
(47, XXY) sterile males, lanky built, feminised physique, difficulties with speech or reading
Triplo-X
(47,XXX) mostly normal but some effect on fertility and intelligence
XYY syndrome
fertile males, above avarage height, not diagnosed
cytoplasmic inheritance
transmission of genes that occur outside the nucleus (mitochondrial DNA and chloroplast DNA)
mtDNA contains
components required for translocation (tRNA, rRNA)
structural genes for proteins involved in oxidative phosphorylation
many genes have transfered from mtDNA to nuclear genome
cpDNA contains
genes encoding tRNAs and rRNAs involved in chloroplast translation
structural genes for proteins involved in photosynthesis
unipaternal inheritance of extracellular genomes
usually maternal inheritance, in plants also biparental or paternal
mtDNA diseases
signs and symptoms highly variable, >1000 mitochondrial proteins are encoded by the nuclear genome - can give "mitochondrial disease" symptoms
Heteroplasmy
Presence of both normal and mutated mtDNA, resulting in variable expression in mitochondrial inherited disease
complex traits
traits controlled by multiple genes, the interaction of genes with each other, and with environmental factors where the contributions of genes and environment are undefined
Mendelian traits
controlled by a single gene and unaffected by environmental conditions
threshold model
model that best explains mulitfactorial traits/ diseases; there is a qualitative point at which the trait/ disease manifests
families with increased risk of a disease
liability is shifted towards the threshold
total phenotypic variance (Vp)
Vp = Vg (genetic variance) + Ve (environmental variance)
Heritability
proportion of the total phenotypic variance due to genes
H^2=
Vg/Vp, where H^2 is between 0 and 1
high heritability
genetic differences in the population explain a high proporition of phenotypic variation
monozygotic twins
share all alleles and the environment, relatedness: 1
dizygotic twins
share the environment and half of the alleles, relatedness:0.5
concordance
the probability that a pair of individuals will both have a certain characteristic, given that one of the pair has the characteristic
the more resemblance of the train in MZ
the more the genes contribute to the variation of the trait
linkage equilibrium
each haplotype is present at the frequency expected from the allele frequencies EF(AB)=F(A)xF(B)
linkage disequilibrium
nonrandom association between genetic variants within a haplotype
sister chromatids
Replicated forms of a chromosome joined together by the centromere and eventually separated during mitosis or meiosis II.
synapsis
Pairing of homologous chromosomes
Telomere
repetitive DNA at the end of a eukaryotic chromosome
Developmental Biology
the study of the complete development of an individual from fertilization to death
advancements in developmental biology
better understanding of the undelying basis of congenital birth defects
novel and more effective treatments for human diseases (regenerative medicine)
aquisition of phenotype, given that selection acts upon phenotype one cannot understand evolution without understanding development
Arabidopsis
a model organism, and the first plant to have its entire genome sequenced
Dictyostelium
cellular slime mold, social behaviour, multicellularity, sequenced genome
Hydra
cnidarian sexual and asexual reproduction, high regenerative capacity
Planarians
free-living flatworms, adult stem cells, bilateral symmetry, triploblastic
Caenothabditis
nematode worm short generation time, hermaphrodites, study of aging
Drosophila melanogaster
fruit fly, short generation time, sequenced genome, transgenesis, imaging
Parhyale
amphipod crustacean, high regenerative capacity, transparent (good for imaging), sequenced genome
Strongylocentrotus
sea urchin, basal deuterostome, transparent embryos, injection of nucleic acids
Ciona
tunicate or sea aquirt, basal chordate (urochordate), imaging
Brachiostoma
amphioxus, basal chordate (cephalochordate), sequenced genome
Danio
zebrafish, vertebrae, external development, transparent embryos, regenerative capacity
Xenopus
clawed frog, external development, transparent tadpoles, fast development, easy to perform transplantations
Gallus
chick, overexpression and knockdown experiments, transplantation experiments
Mus
mouse, mammal, pluripotent embryonic stem cells, strong genetics
Homo
human, mammal, induced pluripotent embryonic stem cells
proto
first
deutero
second
blast
bud (embryonic/precursor)
noto
back (dorsal)
meta
after
chord
string/rope
uro
tail
cephalo
head
echino
spiny, prickly
Notochord
A flexible rod that supports a chordate's back, first tissue to differentiate in chordate development
Cephalochordata
animals with notochords extending into their heads (lancets)
descriptive embryology
experiments which aim to define normal embryonic development with minimal disruptions of the process
experimental embryology
experiments which aim to define how embryonic development occurs (i.e when and how do cells aquire their fate), provides mechanistic insight, requires perturbation of normal development processes (transplantation studies)
Morphogenesis
The process by which an organism takes shape and the differentiated cells occupy their appropriate locations. Involves coordinated cell movements
gastrulation
morphogenetic process by which the endoderm, mesoderm and ectoderm layers reach their final positions in the embryo
Neurulation
development of the nervous system, formation of neural tube
blasotmere
a cell in the early embryo
fate map
the assesment of the fate of a cell or group of cells based in lineage labelling (descriptive embryology)
specification map
assesment of what a cell or group of cells will form if removed from their embryonic environment (from neighbours) (experimental embryology)
determined
a cell or tissue is determined if it will still develop according to its fate even when transplanted into another site in the embryo
fate map = specification map
cells within the embryo don't rely on cell-cell communication to achieve their normal fate (mosaic development - asymmetric inheritance of cytoplasmic determinants)
assymetric inheritance of cytoplasmic determinants
...
fate map =/= specification map
cells will recieve signals or instructions from its environment at a later point of development, prior to assuming their normal fate (regulative development)
competence
range of cell fates which can be achieved by a cell group od cells, given the appropriate conditions
induction
the process by which a cell emits signals to its neighbouring cells therby changing their fate
the organizer experiment
indution of muscle and neural tissue
dorsal mesoderm is determined by the early gastrula stage
ventral ectoderm and mesoderm are competent to become neural and somitic tissue
organizer
dorsal mesoderm at the gastrula stage which induces overlying ectoderm to become neural and induces neighouring mesoderm to become muscle
Nieukoop centre
region of the early dorsal vegetal pole in blastula stage which induces the organizer
homeotic mutation
a mutation that causes a change in the placement of body parts, like causing a developing fly's antenna to be replaced by a leg
Hox genes
family of genes which encode related transcription factors characterised by containing the DNA binding domain called homeodomain or homobox. Evolutionarily conserved
tandem gene duplication
uncequal cross-over caused bt chromosome mis-pairing at meiosis, possibly caused by repeat DNA sequences
segmental duplictation
giant tandem duplication, affecting whole chunk of a chromosome
allotetraploidy
hybridization between two separate species, followed by failure in meiosis
autotetraploidy
Duplication of genome through improper meiosis
Hox paralogues present in mammals arose
from a combination of tandem, segmental and whole genome duplication events
How many HOX genes do humans or mice have?
39
How are hox genes arranged?
four clusters on four chromosomes, evolved from a set of 13 hence 13 paralogous groups
Hox expression gives
positional identity along the anterior-posterior axis
Hox genes expression evidence
expression pattern
comparative embryology
gene knockout experiments
Hox genes are expressed in distinct
proximal-distal patterns
homologous genes
genes that share a common ancestral gene
paralogous genes
Homologous genes that are found in the same genome as a result of gene duplication.
orthologous genes
Homologous genes passed in a straight line from one generation to the next. (same gene in different organism)
gene redundancy
the phenomenon that one gene can compensate for the loss of function of another gene, the presence of a paralogous gene masks the role of the mutated gene
what is the eyeless gene in Drosophila required for?
eye formation
potency
the range of cell fates avaliable to a cell or group of cells
totipotent
Stem cells with the potential to differentiate into any type of cell.
Pluripotent
Cells that are capable of developing into most, but not all, of the body's cell types
bipotent
can become either of two types
Unipotent
describes the condition of being committed to a single specialized cell type
halt development
maintain cells in a pluripotent state long term in a culture
why are hES and iPS cells valuable?
used to study human embryonic development in vitro
generate organs in vitro
model genetic diseases in vitro
harnessed to treat genetic diseases in humans
adult stem cells
Cells present in adult tissues that generate replacements for nondividing differentiated cells that can be of great therapeutic potential.
bone marrow transplant
first successful example of stem cell therapy in human patients
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