the process by which species gradually change over time.
an English naturalis. He studied the plants and animals of South America and the Pacific islands, and in his book On the Origin of Species by Means of Natural Selection (1859) set forth his theory of evolution.
the ship Darwin sailed on a 5 year trip around the world. He studied fossils (preserved remains of organisms) in Argentina and Brazil and zoology (types of animals) in the Galapagos Islands.
a statement that has been backed up by experimentation. It is not a fact. It is only as strong as its evidence!
diversity (how Darwin's trip changed his thinking)
an infinite number of animals and plants, each with adaptations suited to their environment.
fossils (how Darwin's trip changed his thinking)
older bones were similar but different to newer bones.
adaptations (how Darwin's trip changed his thinking)
animals from the same species appeared to develop traits to survive in new environments.
On the Origin of Species
Darwin's most famous book which contained observations from his trip.
theory of evolution
species gradually change over time to adapt better to their environment.
theory of natural selection
organisms better adapted to their environment will survive and reproduce-"Survival of the Fittest".
what causes natural selection to happen?
overproduction, variation, and competition. Changes to environment can affect an organisms ability to survive and can lead to selection.
species that produce more offspring survive better.
offspring differ from each other in many ways.
a limited supply of food and other resources and presence of predators leads to competition between species.
evidence supporting theory of evolution
fossils, similarities in early development, DNA comparisons
the preserved remains of an organism
adaptations that organisms inherited from a common ancestor.
adaptations that are similar because of a common environment.
early development: organisms at birth
comparing animal fetuses shows similarities not obvious in adult form.
comparing animal DNA and gene makeup shows similarities not obvious in adult form.
a diagram that identifies time points where new species are made. Shows how different organisms evolved from each other. Less levels of shared classification = bigger differences in appearance.
when do new species form?
when a group of individuals remains isolated from the rest of its species long enough to evolve different trait.
how do fossils form?
1) Animal dies and is buried under layers of sediments (particles of soil and rock)
2) Sediments harden to become rock and animal is preserved as a fossil
3) Rock erodes and fossil is exposed
types of fossils
petrified, molds/casts, preserved
minerals soak into bones, turning them into rocks.
bones dissolve, leaving gaps.
full animal stored in ice or other minerals.
Fossils found higher on rock are younger than fossils found lower on rock.
Used to compare fossils.
Does not tell scientists actual age.
Compare amount of radioactive element in fossil to amount of other elements in which it breaks down
Work backwards from present to calculate age.
unstable elements that decay (break down) into different elements.
time it takes for half the atoms in a sample to decay.
the millions of fossils scientists have collected over time.
geologic time scale
calendar of Earth's History, created using radioactive dating from fossils.
Calendar goes backwards-starts millions of years ago, ends at present time.
unanswered questions about evolution
what causes mass extinctions?
do species evolve by gradualism or punctuated equilbria?
scientists hypothesize (make an educated guess) that major climate change is responsible.
evolution occurs slowly but steadily over time, which is how Darwin thought evolution occurred.
the theory that species evolve by rapid changes separated by long periods of little or no change, which accounts for gaps in the fossil record.
a living thing.
made of one cell, such as bacteria.
made of many cells, such as animals.
characteristics that all living things share
have a cellular organization, contain similar chemicals (water, proteins, carbohydrates, lipids/fats, and DNA), use energy, respond to their surroundings, grow and develop, reproduce.
a change in an organism's surroundings that causes the organism to react.
a reaction or change in behavior.
organisms use energy to get bigger
the process of change that occurs during an organism's life to produce a more complex organism.
produce offspring through seeds, eggs, or clones.
theory of spontaneous generation
the mistaken idea that living things can arise from non-living things. Scientists found this by observing flies growing from dead meat.
the process of grouping things together based on their similarities.
why do scientists classify?
to make organisms easier to study.
the classification of living things by similar traits.
a pioneer of Taxonomy who developed organism naming system that is used today Each organism has 2 names: genus and species. 1st: Genus - Group of organisms that are closely related. 2nd: Species - Distinct feature of the species. Capitalize genus but not species.
are used to determine the identity of an organism. They use traits to classify organisms.
levels of classification
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species (Didn't Kin
more levels two organisms share = more similar they are.
evolution and classification
species with similar ancestors and similar cell structure are classified more closely together.
1st step on the classification ladder. Based on: cell type, make food/eat food, and number of cells in body.
get food from sunlight/other chemicals.
get food from other organisms.
an organism without a nucleus in their cells.
an organism with a nucleus in their cells.
prokaryote, unicellular, autotrophs and heterotrophs.
prokaryote, unicellular, autotrophs and heterotrophs.
Difference from bacteria: found in extreme conditions, heat, acid, salty, sewage.
organisms have cells with a nucleus.
Divided into 4 kingdoms, protists, fungi, plants, animals.
eukaryote, unicellular and multi-cellular (algae), autotroph and heterotroph.
eukaryote, multi-cellular (except for yeast) heterotrophs that digest food outside their body & then absorb it.
eukaryote, multi-cellular autotrophs that absorb sunlight to make glucose.
eukaryote, multi-cellular heterotrophs that capture and eat their food.
cilia and flagella
shape and size of bacteria
spherical shape, rod shape, and spiral shape.
size ranges from 1/1,000th of a meter to 1/1,000,000th of a meter.
reproduction of bacteria
asexual: binary fission
one cell divides to form two identical cells.
the study of heredity
transmission of DNA from parents to offspring
"The Father of Genetics." A priest and a gardener who cross-fertilized purple and white plants. First he found that all 4 of the F₁ generation was purple, then he found that 1 out of 4 of the F₂ was white.
characteristic of an organism that is passed down, such as seed color or stem height.
combine the sperm from one organism with the egg of another organism.
an organism that has the same alleles for a trait.
offspring of the p generation.
offspring of the f₁ generation.
the different forms of a gene. Each organism must have 2 of these from each trait, one from Mom's and Dad's.
an allele whose trait always shows up in the organism when the allele is present. Represented by a capital letter.
an allele that is hidden whenever the dominant allele is present. Represented by a lowercase letter
the factors that control a trait, a segment of DNA on a chromosome that codes for a trait.
the passing of physical characteristics from parents to offspring.
an organism that has two different alleles for trait.
a chart used to predict the results of a genetic cross. Used to predict the outcome of meiosis
the likelihood that something will happen. It is a prediction, not a fact.
the alleles of an organism.
same alleles for a trait, purebred.
different alleles for a trait, hybrid.
the physical appearance of an organism.
when two or more alleles have equal dominance, so hybrids show both alleles. Write these alleles as superscripts.
all of the DNA in one cell of an organism.
chromosomes in a human cell
23 pairs-one from mom and one from dad.
a structure in the nucleus that contains genetic material.
50% of DNA.
100% of DNA.
chromosomes with matching information.
produce offspring with identical DNA from 1 organism-use mitosis.
produce offspring with DNA from 2 different organisms.
the process that occurs in the formation of sex cells (sperm and egg) by which the number of chromosomes is reduced by half.
each half of the chromosome.
holds the 2 chromatids together.
objective of meiosis
make a 4 sex haploid cells from a diploid cell where haploid contains 1 allele of each gene.
purpose of meiosis
to make 4 sex cells to pass on to the next generation.
How do we make babies with shared characteristics from each parent?
need to make cells with half of the DNA from each parent and then merge them into a new cell.
x and y chromatids
determine the gender of an organism.
meiosis 1: start
cell nucleus has 4 chromatids: 2 from mom and 2 from dad.
meiosis 1: prophase
cell makes copy of each chromatid-4 homologous chromosomes; mom and dad chromosomes swap similar genes.
meiosis 1: metaphase
mom and dad chromosomes line up in the center of the cell, and are held together by spindle fibers attached to the centromeres.
meiosis 1: anaphase
nucleus breaks down and chromosomes are pulled apart by spindle fibers-cell divides.
meiosis 1: telophase
cell ends up with two chromosomes each, having one allele of each gene from mom and dad.
new cells split again to produce 4 new cells, with two chromatids each-1 chromatid from mom and 1 from dad.
what doesn't happen in Meiosis 2?
DNA does not copy.
deoxyribonucleic acid, contains genetic material in 2 strands.
a segment of DNA that consists of sugar, phosphate, and nitrogenous base.
connection between nucleotides.
code of DNA (adenine, thymine, cytosine, guanine)
adenine goes to thymine; cytosine goes to guanine.
relation between each strand of nucleotide
top strand is the reverse of the bottom strand.
how to copy DNA
top strand "unzips", give DNA to offspring.
an error of copying DNA. Errors can create new alleles. Can effect trait, phenotype, and chance of getting disease.
an error of copying DNA. Errors can create new alleles. Can effect trait, phenotype, and chance of getting disease.
ribonucleic acid, contains uracil instead of thymine in DNA. Assists in protein synthesis by carrying code from DNA to ribosome in cytoplasm.
In 1869, he discovers a white substance in the nucleus of cells.
In 1920, he finds that DNA contains:
a) DNA Backbone: Deoxyribose Sugar and Phosphates
b)Nitrogen Bases (A, G, C, T)
In 1952, she takes X-ray photos of DNA and shows it looks like a helix.
James Watson and Francis Crick
In 1953, they use Franklin's data (without permission) to show that DNA looks like a double helix.
Where do organisms get each set of their genes?
From their parents (Mom and Dad).
form the parts of an organism and carry out all of an organism's functions.
what an object is made of and how its parts are put together.
the processes that enable it to stay alive and reproduce.
In 1660 he used his compound microscope to look at slices of cork. He saw boxes and called them cells because they looked like small rooms.
Anton van Leeuwenhoek
In 1673, he used a simple microscope and saw living things in pond and lake water.
In 1838, he saw that all plants were made of cells.
In 1838, he saw that all animals were made of cells.
In 1855, he saw cells dividing to make more cells.
1) All living things are made of cells.
2) Cells are the basic units of structure and function of living things.
3) All cells are made from other cells.
1st level of organization-cells
building block of all structures.
2nd level of organization-tissues
a group of cells that perform a specific function.
3rd level of organization-organ
a group of tissues that perform a specific job-heart.
4th level of organization-organ system
a group of organs that work together to perform a specific job.
a tiny cell structure that carries out a specific function within the cell.
holds organelles in cell
Controls transport in/out of cell-front gate.
contains all code for:
Building new organelles.
Turning organelles on/off-control center.
respiration: Break down sugars to provide energy for cell-power source.
produce proteins-machines of cell.
the process of producing proteins by ribosomes.
endoplasmic reticulum (ER)
transporting objects around the cell-highway.
covered with ribosomes.
package objects for transport inside and outside of cell-post office.
stores supplies: water, salts & sugars-closet.
(only in plant) storage of water, salts & sugars.
supports structure of cell.
releases chemicals that break down dead organelles.
Recycles parts for ribosomes-trash can.
used for Mitosis - Cell Replication.
maintain cell structure.
Hold organelles in place.
the structure in the nucleus which produces ribosomes.
the soupy material between the cell membrane and the nucleus.
form the internal structure of the centrioles and helps move organelles.
(only in plant) protects and support the cell.
Give structure strength.
(only in plant) contain pigments called chlorophyll.
Use sunlight to carryout photosynthesis.
a green pigment in plants that absorbs light energy used to carry out photosynthesis.
what we learned from Robert Brown's work.
Particles are always constantly moving in random directions.
Randomly moving particles that hit each other will move in opposite directions.
tendency of particles to move from high concentrations to low concentration-a type of passive transport.
permeable cell membrane
all particles can pass through.
selectively permeable cell membrane
some particles can pass through.
impermeable cell membrane
no particles can pass through.
water, oxygen, food, messages.
diffusion of molecules through a semipermeable membrane that is driven by the presence of sugars/salts on one side from a place of higher concentration to a place of lower concentration until the concentration on both sides is equal.
water and sugar molecules
water molecules bind to sugar molecules.
Cells contain sugar molecules (used for energy).
Cell membrane is:
Permeable to water.
Impermeable to sugars.
equal amounts of sugars/salts in and out of membrane-stays same shape.
more sugars/salts out of cell-water travels out.
more sugars/salts in cell-water travels in.
composition of cell membrane
Made of particles called phospholipids. They have two parts: hydrophobic and hydrophilic.
part of phospholipid that doesn't like water.
part of phospholipid that likes water.
organization of phospholipids
phospholipids organize into a double layer to form the cell membrane because of the two parts.
movement from high concentration to low concentration without using energy.
Phospholipids move around.
used to prevent membrane from moving.
during active transport, they pick up molecules and carrying them in using energy.
Cells need particles that are hard to find.
Concentration of particles outside the cell is very low.
Passive transport cannot be used to get particle into cell-needs energy.
Use energy (ATP) to force particles from low concentration to high concentration.
a type of active transport where cells capture particles by engulfing them.
a type of active transport where cells get rid of particles which are packaged by the golgi body by spitting them out.
holes in a membrane.
complex cells that contain a nucleus, organelles and a genetic material with many chromosomes.
the process that eukaryotic cells use to make identical copies of themselves.
strands of genetic material.
steps of cell cycle
interphase, mitosis, cytokinesis.
stages of mitosis
prophase, metaphase, anaphase, telophase.
1st stage of cell cycle. Cell grows in size; makes a copy of DNA in nucleus; makes more organelles; makes centrioles.
organelle in an animal cell that helps to organize cell division and make microfilaments.
1st stage of mitosis. Chromosomes form chromatid structure; identical chromatids connect to each other using a centromere
one of two identical strands into which a chromosome splits during mitosis.
area where the chromatids of a chromosome are attached.
2nd stage of mitosis. Centrioles move to either side of nucleus; chromosomes line up in center; spindle fibers connect chromosomes to both centrioles.
connect chromosome to both centrioles and pull chromosomes to either side in metaphase.
3rd stage of mitosis. Centromeres split in half-chromotids copy 1 go up, chromatids copy 2 go down.
4th stage of mitosis. Nuclear membrane forms around 2 groups of chromatids. Chromatids structure go back to chromosome DNA. Cell starts to split into two.
Cell splits into two new cells. Each has own organelles and DNA. Membrane pinches together.
Cell splits into two new cells. Each has own organelles and DNA. Cell plate forms in center and becomes membrane.