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Biology 100
Midterm #2
276
Biology
Undergraduate 1
11/10/2015

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Term
How is life distinguished from nonliving matter?
Definition
ability to produce more of their own kind
Term
Cell Division
Definition
reproduction of cells
Term
Cell Cycle
Definition
life of a cell from when its formed via division from a parent cell, until it divides into daughter cells
Term
Cell Division is necessary in multicellular organisms for: (3)
Definition
-Development from a fertilized cell
-Growth
-Repair
Term
Genome
Definition
all genetic information within a cell
Term
Chromatin
Definition
are packed with a cell's DNA molecules, which is further grouped into chromosomes
Term
Order:
chromatin, chromosomes, DNA
Definition
DNA-> chromatin -> chromosomes
Term
Somatic Cells
Definition
non reproductive cells, have 2 sets of chromosomes
Term
Gametes
Definition
reproductive cells (sperm&eggs) half as many chromosomes as somatic cells; a single set.
Term
What happens in preparation for cell division?
Definition
DNA is replicated and the chromosomes condense
Term
Sister Chromatid
Definition
joined copies of the original chromosome
Term
Centromere
Definition
"waist" of the duplicated chromosome, where the two chromatids are most closely attached.
Term
Once separated, the chromatids are now called...
Definition
Chromosomes, and there are now double the number of chromosome in the cell.
Term
Mitosis
Definition
Division of genetic material in the nucleus
Term
Cytokinesis
Definition
Division of the cytoplasm. Begins during anaphase or telophase and the spindle eventually disassembles.
Term
Interphase
Definition
cell growth and copying of chromosomes in preparation for cell division. (90% of cell cycle)
Term
Miotic Phase (M)
Definition
mitosis and cytokinesis
Term
3 Phases of interpase
Definition
-G1 phase (1st gap)
-s phase (synthesis) chromosomes are duplicated
-G2 phase (second gap)
Term
5 Phases of Mitosis
Definition
1. prophase
2. prometaphase
3. metaphase
4. anaphase
5. telophase
Term
G2 of interphase
Definition
second gap.
Nuclear envelop encloses nucleus.
2 centrosomes formed from duplication of a single centrosome.
Chromosomes duplicated (during S phase) cannot be seen individually because they have not yet condensed.
Term
Prophase
Definition
Chromosomes condense.
Nucleoli disappears.
Each duplicated chromosome appears as two identical sister chromatids joined at their centromeres
Miotic spindle begins to form.
centrosomes move away form each other.
Term
Prometaphase
Definition
nuclear envelop fragments.
microtubules extending from each centrosome invade the nuclear area.
Each of the two chromatids of each chromosome now has a kinetochore.
Kinetochore microtubules jerk chromosomes back and forth.
non-kinetochore microtubules interact with those from the opposite pole of the spindle.
Term
Metaphase
Definition
Centrosomes are now at opposite poles of the cell.
Chromosomes line up at the metaphase plate.
For each chromosome, the kinetochore of the sister chromatids are attached to kinetochore microtubules coming from opposite poles.
Term
Miotic Spindle
Definition
structure made of microtubules that controls chromosome movement during mitosis.
Term
Centrosome
Definition
microtubule organizing center.
replicates during interphase (forming two centrosomes that migrate to opposite ends of the cell during prophase and prometaphase).
Term
Aster
Definition
radial array of short microtubules that extends from each centrosome
Term
Kinetochores
Definition
Protein complexes associated with centromeres. During prometaphase, some spindle fibers attach here on the chromosome and begin to move them.
Term
Metaphase Plate
Definition
imaginary structure at the midway point between the spindle's two poles
Term
Anaphase
Definition
shortest stage of mitosis.
sister chromatids separate(each becoming a full-fledged chromosome) and move along the kinetochore microtubules towards opposite ends of the cell as kinetochore microtubules shorten. Non-kinetochore microtubules overlap and push against eachother, elongating the cell.
Term
NonKinetochore Microtubules
Definition
microtubules not attached to the kinetochores that elongate the cell.
Term
Telophase
Definition
genetically identical daughter nuclei form at opposite ends of the cell. Nuclear envelopes arise from the fragments of the parent cell's nuclear envelope and other portions of the endomembrane system. Nucleoli reappear.
chromosomes become less condensed.
Any remaining spindle microtubules are depolynerized.
Term
Cytokinesis in:
Animal Cells
Plant Cells
Definition
Animal Cells- cleavage furrow
Plant Cells- cell plate
Term
Binary Fission
Definition
-Cell division used by prokaryotes
-Chromosome replicates and two daughter chromosomes actively move a part, followed by the plasma membrane pinching inward.
Term
Binary Fission Steps (4)
Definition
1. Chromosome replication begins
2. Replication continues
3. Replication finishes
4. Two daughter cells result
Term
Cell Control System
Definition
-Directs sequential events of the cell cycle.
-similar to a clock.
-regulated by both internal and external controls
Term
Checkpoints (in the cell control system)
Definition
where the cell cycle stops until a go-ahead signal is received.
Term
Importance of the G1 Checkpoint
Definition
if a cell receives a go-ahead signal it will usually complete the S, G2 and M phases the divide. If the cell does not receive the signal it will exit the cycle switching to a non-dividing state. (G0 phase).
Term
G0 Phase
Definition
non-dividing state
Term
2 types of regulatory proteins involved in cell cycle control
Definition
Cyclins and Cyclin-dependent kinases (Cdks)
Term
Cyclins
Definition
concentrations vary throughout the cell cycle
Term
Cdks
Definition
activity controlled by cyclins
cyclin-dependent kinases
Term
MPF (Maturation-promoting Factor)
Definition
a cyclin-Cdk complex that triggers a cell's passage past the G2 checkpoint into M phase.
Term
Example of an Internal Signal acting on the cell cycle
Definition
kinetochoes not attached to spindle microtubules send a molecular signal that delays anaphase
Term
Example of an external signal acting on the cell cycle
Definition
growth factors released or density-dependent inhibition
Term
Growth Factors
Definition
proteins released by certain cells that stimulate other cells to divide
Term
Density-Dependent Inhibition
Definition
crowded cells stop dividing
Term
Anchorage Dependence
Definition
animal cells must be attached to a substratum in order to divide
Term
Loss of Cell Cycle Control:
Cancer Cells
Definition
-exibit neither density-dependent inhibition nor anchorage dependence.
-do not respond normally to the body's control mechanisms: make their own growth factor, convey a growth factor's signal without the presence of the growth factor, have an abnormal cell cycle control system.
Term
Transformation
Definition
process by which a normal cell is converted to a cancerous cell
Term
Tumors
Definition
masses of abnormal cells within otherwise normal tissue
Term
Benign Tumor
Definition
if abnormal cells remain only at the original site
Term
Malignant Tumor
Definition
invades surrounding tissues, can metastasize
Term
Metastasize
Definition
exporting cancer cells to other parts of the body.
Term
Genetics
Definition
scientific study of heredity and variation
Term
Heredity
Definition
transmission of traits from one generation to the next
Term
Variation
Definition
demonstrated by the differences that offspring show from parents and siblings
Term
Genes
Definition
units of heredity that are made up of segments of DNA
Term
Gametes
Definition
sex cells (sperm & eggs) Haploid cells that are produced by meiosis
Term
Locus
Definition
location of a specific gene on a certain chromosome
Term
Asexual Reproduction
Definition
single individual passes genes to its offspring without the fusion of gametes
Term
Clone
Definition
Group of genetically identical individuals from the same parent
Term
Sexual Reproduction
Definition
2 parents give rise to offspring that have unique combinations of genes inherited from the 2 parents
Term
Somatic Cells
Definition
2 sets of chromosomes. Any cell other than a gamete
Term
Karyotype
Definition
ordered display of the pairs of chromosomes from a cell
Term
Homologous Chromosomes
Definition
2 chromosomes in each pair that are the same shape and same genes that control the same inherited characters. Includes 1 chromosome from each parent.
Term
Sex Chromosomes
Definition
determines sex of the individual called x and y
Term
Autosomes
Definition
remaining pairs of chromosomes. Anything without an x and y.
Term
Haploid Cell
Definition
N. contain one set of chromosomes. ex. gametes
Term
Diploid Cell
Definition
2N. has 2 sets of chromosomes ex. skin cell
Term
How many Chromosomes do Humans have?
Definition
2N=46
N=23 (22autosomes&1sex chromosome)
Term
Ovum
Definition
unfertilized egg
Term
Fertilization
Definition
union of gametes
Term
Zygote
Definition
Fertilized egg. contains one set of chromosomes from each parent.
Term
How does the Zygote develop?
Definition
produces somatic cells by mitosis and develops into an adult
Term
3 Main types of sexual life cycles that differ in the timing of meiosis and fertilization:
Definition
1. Animals
2. Plants
3. Fungi and some Protists
Term
Animal Sexual Life Cycle
Definition
Gametes undergo no further cell division before fertilization.
Fuse to form a diploid zygote that divides by mitosis to develop to a multicellular organism.
Dominant life stage is as a diploid organism.
Term
Plant Sexual Life Cycle
Definition
Both a diploid and haploid multi cellular stage.
Diploid organisms (sorophyte) makes haploid spores by meiosis.
Each haploid spore grows by mitosis into a haploid organism (gametophyte).
Fertilization of gametes results in a diploid sporophyte.
Term
Fungi and Protist Sexual Life Cycle
Definition
Only diploid stage is the single-celled zygote; no multi cellular diploid stage.
Zygote produces haploid cells by meiosis; each haploid cell grows by mitosis into a haploid multi cellular organism.
Haploid adult produces gametes by mitosis.
Dominantly exist as a haploid.
Term
Two Sets of Cell Division in Meiosis
Definition
Meiosis 1 and Meiosis 2.
Results in 4 daughter cells with half as many chromosomes as the parent cell.
Term
Meiosis 1
Definition
homologues pair up and seperate, resulting in two haploid daugter cells with replicated chromosomes
Term
Meiosis 2
Definition
sister chromatids seperate. Resulting in 4 daughter cells with unreplicated chromosomes
Term
Prophase 1
Definition
takes of 90% of the time.
Chromosomes begin to condense followed by synapsis.
Crossing over occurs.
Each pair of chromosomes forms a tetrad.
Each tetrad has 1 or more chiasmata
Term
Synapsis
Definition
when homologous chromosomes loosely pair up, aligned gene by gene
Term
Crossing Over
Definition
produces recombinant chromosomes, containing DNA inherited from each parent into a single chromosome. Homologous portions of 2 non-sister chromatids trade places.
Term
Tetrad
Definition
a group of 4 chromosomes
Term
Chiasmata
Definition
x-shaped regions where crossing over occured
Term
Metaphase 1
Definition
Tetrads line up at the metaphase plate, with one chromosome facing each pole.
Microtubules from each pole are attached to the kinetochore of one chromosomes of each tetrad.
Microtubules from the other pole are attached to the other chromosome.
Term
Anaphase 1
Definition
pairs of homologous chromosomes seperate.
1 chromosome moves toward each pole, guided by the spindle apparatus.
Sister chromatids remain attached at the centromere and move as one unit towards the pole.
Term
Telophase 1
Definition
Each half of the cell has a haploid set of chromosomes; each chromosome still consists of two sister chromatids.
Cytokinesis occurs forming two haploid daughter cells
Term
Anaphase II
Definition
sister chromatids seperate
Term
Telophase II and Cytokinesis
Definition
Haploid daughter cells form. Resulting in 4 daughter cells.
Term
3 Events Unique to Meiosis (occur in Meiosis 1)
Definition
Prophase 1- synapsis & crossing over: homologous chromosomes physically connect & exchange genetic info
metaphase 1- paired homologous chromosomes (tetrads) instead of individual replicated chromosomes
Anaphase 1- homologous chromosomes seperate instead of sister chromatids
Term
3 Mechanisms that Contribute to Genetic Variation
Definition
1. independent assortment of chromosomes
2. Crossing Over
3. Random Fertilization
Term
Independent Assortment
Definition
each pair of chromosomes sorts maternal and paternal homologs into daughter cells independently of the other pairs.
Term
# of combinations possible:
Definition
2 to the power of N.
ex. humans- 2 to the power of 23= 8 million possible chromosome combinations
Term
Random Fertilization
Definition
adds to genetic variation because any sperm can fuse with any ovum.
Each gamete has 8.4 million possible chromosome combinations from independent assortment.
Fusion of 2 gametes produces a zygote with any of about 70 trillion diploid combinations.
Term
Where does genetic variation originate from?
Definition
mutations
Term
Blending Hypothesis
Definition
the idea that genetic material from the two parents blends together.
Term
Particulate Hypothesis
Definition
the idea that parents pass on discrete heritable units (genes), explaining the reappearance of traits after several generations.
Term
Gregor Mendel
Definition
Augustinian Monk.
Experiments with garden peas beginning in 1857.
Term
Characters
Definition
distinct heritable features
Term
Traits
Definition
character variants
ex) purple or white
Term
Controlled Mating
Definition
flowers can be cross-pollinated. Pollen (sperm) from the stamens applied to carpels (containing eggs).
Term
3 Reasons why Mendel chose peas:
Definition
1. Controlled mating could be done
2. peas have a short generation time and lots of offspring.
3. many varieties with distinct characters
Term
True-Breeding
Definition
plants that produce offspring of the same variety when they self-pollinate
Term
Hybridization
Definition
process that Mendel used when he mated two contrasting, true-breeding varieties
Term
P generation
Definition
true-breeding parents
Term
F1 Generation
Definition
hybrid offspring of the P generation
Term
F2 Generation
Definition
offspring of F1 individuals that self-or cross-pollinate with other F1 hybrids.
Term
Hybrid
Definition
offspring from two unique parents
Term
Mendel's Peas
Definition
True-bred white and purple coloured pea plants.
All F1 hybrids were purple.
F1 hybrids crossed, many f2 plants had purple flowers, making that the dominant trait. 3 to 1 ratio.
Term
7 Traits Mendel Studied
Definition
1. Flower Colour: d-purple r-white
2. Flower Position d-axial r-terminal
3. Seed Colour d-yellow r-green
4. Seed Shape- d-round r-wrinkled
5. Pod Shape d-inflated r-constricted
6. Pod Colour d-green r-yellow
7. Stem Length d-tall r- dwarf
All with 3:1 ratio D:R
Term
Alleles
Definition
alternative variations of a gene
Term
Locus
Definition
specific place on a specific chromosome
Term
The Law of seregation
Definition
corresponds to the distribution of homologous chromosomes to different gametes in meiosis.
Accounts for the 3:1 ratio that Mendel observed in the F2 generation.
Term
The Law of Segregation
Definition
the 2 alleles for a heritable character separate during gamete formation and end up in different gametes.
Term
Punnett Square
Definition
used to predict allele composition of offspring from a genetic cross between individuals of known genetic makeup.
Capital letter=dominant allele
lowercase letter=recessive allele
Term
Homozygous
Definition
two identical alleles
Term
Heterozygous
Definition
organism has two different alleles for a gene
Term
Phenotype
Definition
physical appearance
Term
Genotype
Definition
genetic makeup
Term
Testcross
Definition
breeding the mystery individual with a homozygous recessive individual. If offspring displays the recessive phenotype, the mystery parent must be heterozygous.
Term
Monohybrids
Definition
individuals that are heterozygous for one character
Term
Monohybrid Cross
Definition
cross between such heterozygotes
Term
Dihybrids
Definition
offspring of crossing two true-breeding parents differing in two characters
Term
Dihybrid Cross
Definition
a cross between f1 dihybrids, can determine whether 2 characters are transmitted to offspring as a package or independently
Term
The law of independent assortment
Definition
each pair of alleles segregates independently of each other pair of alleles during gamete formation.
This law applies only to genes on different, nonhomologous chromosomes or those far a part on the same chromosome.
Genes located near eachother on the same chromosome tend to be inherited together.
Term
Deviation From Simple Mendelian Patterns
Definition
Alleles are not completely dominant or recessive.
Gene has more than 2 alleles.
Gene produces multiple phenotypes.
Term
Complete Dominance
Definition
phenotypes of the heterozygote and dominant homozygote are identical
Term
Incomplete Dominance
Definition
the phenotype of f1 hybrids is between the phenotypes of the two parental varieties. Some cells show red and some show white which appears pink (not blending)
Term
Codominance
Definition
two dominant alleles affect the phenotype in separate distinguishable ways
Term
Pleiotropy
Definition
when genes have multiple phenotypic effects.
Responsible for the multiple symptoms of certain heredity diseases, such as cystic fibrosis and sickle-cell disease.
Term
Epistasis
Definition
A gene at one locus alters the phenotypic expression of a gene at a second locus. ex. colour coat in Labrador retrievers
one gene determines the pigment colour; the other gene determines whether the pigment will be deposited in the hair.
Term
Quantitative Characters
Definition
are those that vary in the population along a continuum.
Term
Polygenic Inheritance
Definition
additive effect of two or more genes on a single phenotype.
ex)skin colour
Term
Norm of Reaction
Definition
phenotypic range of a genotype influenced by the environment. ex. hydrangeas of the same genotype range from blue-violet to pink, depending on soil acidity. ex tanning
Term
Pedigree
Definition
a family tree that describes the inter relationships of parents adn children across generations.
Term
Carriers
Definition
heterozygous individuals who carry the recessive allele but are phenotypically normal
Term
Early Onset Alzheimer's
Definition
autosomal dominant- if one parent has it the offspring have a 50/50 chance of inheriting it. Caused by single gene mutations on anyone of various locations on chromosomes 21, 14, and 1.
Term
The Chromosome Theory of Inheritance
Definition
Mendelian genes have specific loci (positions) on chromosomes.
Chromosomes undergo segregation and independent assortment.
Term
Thomas Hunt Morgan
Definition
associating a specific gene with a specific chromosome.
experimented with fruit flies
Term
Wild Type
Definition
normal phenotype
Term
Mutant Phenotype
Definition
traits alternative to the wild type
Term
Sex-linked Gene
Definition
gene located on either sex chromosome
Term
Y-linked vs. X-linked Gene
Definition
y- on y chromosome. mainly encode genes related to sex determination.
x-on x chromosome. have genes for many characters unrelated to sex.
Term
SRY Gene
Definition
on Y chromosome, codes for a protein that directs the development of male anatomical features.
Term
For a recessive x-linked trait to be expressed:
Definition
Female needs 2 copies of the allele, male needs 1 copy of the allele
Term
Linked Genes
Definition
genes located on the same chromosome that tend to be inherited together
Term
Genetic Recombination
Definition
production of offspring with combinations of traits differing from either parent, occurs due to crossing over.
Term
Nondisjunction
Definition
pairs of homologous chromosomes do not separate normally during meiosis.
one gamete receives two of the same type of chromosome, and another gamete receives no copy
Term
Aneuploidy
Definition
abnormal number of a particular chromosome, results from the fertilization of gametes in which nondisjunction occured.
Term
Polyploidy
Definition
condition in which an organism has more than two complete sets of chromosomes (common in plants, rare in animals)
Term
Triploidy
Definition
3 sets of chromosomes
Term
tetraploidy
Definition
4 sets of chromosomes

AND SO ON.
Term
Deletion
Definition
a deletion removes a chromosomal segment
Term
Duplication
Definition
a duplication repeats a segment
Term
inversion
Definition
reverses a segment within a chromosome
Term
Translocation
Definition
moves a segment from one chromosome to a nonhomologous chromosome.
Term
Double-Helical DNA Model
Definition
1953.
James Watson and Francis Crick
Rosalind Franklin's x-ray crystallographic images of DNA enabled Watson to deduce that DNA was helical.
Term
Antiparallel
Definition
subunits run in opposite direction
Term
DNA
Definition
polymer of nucleotides. Consists of a nitrogeneous base, sugar and a phosphate group.
Term
Semi conservative Model
Definition
predicts that when a double helix replicates, each daughter molecule will have one old strand and one newly made strand.
Term
Origins of Replication
Definition
replication begins here...2 DNA strands are separated, opening up a replication "bubble"
Replication proceeds in both directions from each origin, until the entire molecule is copied.
Term
Replication Fork
Definition
Y-shaped region where new DNA strands are elongating.
Term
Helicases
Definition
enzymes that untwist the double helix at the replication fork
Term
RNA Primer
Definition
initial nucleotide strand is short (5-10 nucleotides long) synthesized by primase.
Term
Primase
Definition
enzyme that adds RNA nucleotides one at a time (starting at the 3' end) using the parental DNA as a template.
Term
DNA Polymerases
Definition
enzymes that catalyze the elongation of new DNA at a replication fork by adding nucleotides to a pre-existing chain. Proofread DNA.
DNA polymerases add nucleotides only to the free 3' end of a growing strand; therefore a new DNA strand can elongate only in the 5' to 3' direction.
Term
Leading Strand
Definition
made continuously, moving towards the replication fork
Term
Lagging Strand
Definition
DNA polymerase must work in the direction away from the replication fork
Term
Okazaki Fragments
Definition
segments that make up a lagging strand
Term
DNA Ligase
Definition
joins okazaki fragment together
Term
Mismatch Repair
Definition
repair enzymes correct errors in base pairing
Term
Nucleotide Excision Repair
Definition
Nuclease cuts out and replaces damaged stretches of DNA.
Term
Telomeres
Definition
special nucleotide sequences at the ends of eukaryotic chromosomal DNA molecules. Act as a buffer, non-coded, not important.
Term
Do Telomeres prevent the shortening of DNA?
Definition
no. but hey postphone the erosion of genes near the ends of DNA molecules. Shortening of telomers is connected to aging.
Term
Histones
Definition
proteins responsible for the first level of DNA packing in chromatin
Term
Gene Expression
Definition
process by which DNA directs protein synthesis, includes 2 stages: transcription and translation
Term
Transcription
Definition
synthesis of RNA using information in DNA; produces messenger RNA (mRNA)
Term
Translation
Definition
synthesis of a polypeptide, using information in the mRNA; happens in ribosomes.
Term
Cellular Chain of Command:
Definition
DNA->RNA->Protein
20 amino acids, 4 neucleotide bases in DNA.
Term
Triplet Code (Codons)
Definition
series of nonoverlapping, 3-nucleotide "words". read in the 5' to 3' direction.
Term
Template Strand
Definition
provides a template for ordering the sequence of complementary nucleotides in an RNA transcript.
Term
How many Codons are there?
Definition
64 codons. 61 code for amino acids and 3 are stop signals that end translation.
Term
RNA polymerase
Definition
catalyzes RNA synthesis. Pries a part and hooks together the RNA nucleotides.
Term
3 Stages of Transcription
Definition
1. initiation
2. elongation
3. termination
Term
Transcription: Initiation
Definition
Promoter: DNA sequence where transcription is initiated by the binding of transcription factors.
Term
Transcription Factors
Definition
mediate the binding of RNA polymerase
Term
Transcription: Elongation
Definition
RNA polymerase untwists the double helix and adds nucleotides to the 3' end of the growing RNA molecule.
Term
Transcription: Termination
Definition
Terminator RNA sequence is transcribed, causing the polymerase to detach and release the transcript
Term
Transfer RNA (tRNA)
Definition
transfers mRNA message to protein and transfers amino acids to the growing polypeptide in a ribosome
Term
What are the 4 binding sites on each ribosome for?
Definition
3 binding sights for tRNA and 1 binding site for mRNA.
Term
3 steps of translation
Definition
1. initiation
2. elongation
3. termination
Term
Translation: Initiation
Definition
small ribosomal subunit binds to a molecule of mRNA and locates the start codon, where an initiator tRNA base-pairs (P site). Large subunit completes the initiation complex.
Term
Translation: Elongation
Definition
amino acids are added one at a time, mediated by proteins
Term
Translation: Termination
Definition
stop codon is reached on mRNA, the A site of the ribosome accepts a "release factor" freeing the polypeptide from the ribosome.
Term
To Make a functional Protein (4):
Definition
-coils and folding (primary structure)
-chemical modification (addition of sugards, lipids, etc)
-Removal of amino acids
-Broken into 2 or more pieces (ex insulin)
Term
Mutations
Definition
changes in genetic material of a cell or virus
Term
Frameshift Mutations
Definition
production of an abnormal protein where incertion or deletion of nucleotides may alter the reading frame (things no longer line up)
Term
Sponaneous Mutations
Definition
can occur during DNA replication, recombination or repair.
Term
Mutagens
Definition
physical or chemical agents that can cause mutations. ex. radiation
Term
Darwin
Definition
was on Beagle voyage where he observed south american plants and animals.
Term
Adaptations
Definition
inherited characteristics of organisms that enhance their survival and reproduction in specific environments
ex. beak variation in Galapagos finches
Term
Natural Selection
Definition
process by which individuals with certain inherited traits are more likely to survive and reproduce.
Term
Descent with Modification (3)
Definition
1. the unity of life
2. the diversity of life
3. the match between organisms and their environment
Term
Artificial Selection
Definition
human modification of other species by selecting and breeding individuals with desired traits
Term
2 Observations Darwin Made
Definition
1. individuals in a population vary in their heritable characteristics.
2. Organisms produce more offspring than the environment can support.
Term
2 Inferences that Darwin Made
Definition
1. Individuals that are well suited to their environment tend to leave more offspring than other individuals.
2. over time favorable traits accumulate in the population
Term
3 Key point of the Evolutionary theory
Definition
1. individuals do not evolve; populations do
2. NS can alter traits within a population only if there is variation in traits
3. NS depends on the context in which a species lives and mates (a trout that is favorable in the environment may be useless in another)
Term
4 Types of Data Used to Document Evolution
Definition
1. Direct observations of evolution.
2. Homology.
3. Fossil Record
4. Biogeography
Term
Homology
Definition
similarity resulting from common ancestry-> related species have characteristics with an underlying similarity, even if they function differently.
Can be anatomical (homologous structures) and molecular.
Term
Fossil Records Document:
Definition
How past organisms differed from present
extinction of species
evolutionary changes
origins of new groups of organisms
ex)fossil records of cetaceans (whales and dolphins) help explain how cetaceans originated from land mammals by documenting changes in limb structure
Term
Biogeography
Definition
geographic distribution of species. we can study where species are found (currently and historically) to understand how species change over time in different environments.
ex) continental drift, island biogeography
Term
Microevolution
Definition
change in allele frequencies in a population over generations
Term
3 Mechanisms that causes allele frequency change:
Definition
1. Natural selection
2. Genetic drift
3. Gene flow
Term
Discrete vs. Quantitative Basis
Definition
d= either or bases
q=variation along a continuum
Characters both discrete and quantitative contribute to variation within a population
Term
Average Heterozygosity
Definition
measures the average percent of loci that are heterozygous in a population
gene variablility
Term
Genetic Variation Can be measured as:
Definition
Gene variability and Nucleotide Variability
Term
Gene Variability
Definition
average heteroyzyosity measures the average percent of loci that are heterozygous in a population
Term
Nucleotide Variability
Definition
measured by comparing the DNA sequences of pairs of individuals
Term
Geographic Variation
Definition
differences between gene pools of separate populations
Term
Cline
Definition
graded change in a trait along a geographic axis
Term
Population
Definition
localized group of individuals capable of interbreeding and producing fertile offspring
Term
Gene Pool
Definition
consists of all alleles for all loci in a population
Term
When is a locus fixed?
Definition
if individuals in a population are homozygous for the same allele
Term
Total # of Alleles at a locus =
Definition
Total # of individuals X2
Term
Total # of Dominant Alleles at a locus=
Definition
2 alleles for each homozygous dominant individual + 1 allele for each heterozygous individual.

same logic applies for ressive alleles
Term
Frequency of all alleles in a population will add up to 1
Definition
p+q=1
Term
Hardy-Weinberg Principle
Definition
describes a population that is not evolving.
Frequencies of alleles and genotypes in a population remain constant from generation to generation. Allele frequencies will not change when gametes produce to the next generation randomly.
Term
Probability that 2 Alleles will come together=
Definition
pxp
qxq
2pq
(pxp)+(qxq)+(2pq)=1
Term
5 Conditions of Hardy-Weinberg Theorem
Definition
1. no mutations
2. random mating
3. no natural selection
4. extremely large population size
5. no gene flow
Term
Rules of Probability
Definition
the smaller a sample, the greater the chance of deviation from a predicted result
Term
Genetic Drift
Definition
describes how allele frequencies fluctuate unpredictably from one generation to the next. Tends to reduce variation through losses of alleles.
Term
Founder Effect
Definition
A few individuals become isolated from a larger population. Allele frequencies may differ between populations.
Term
Bottleneck Effect
Definition
sudden reduction in population size due to a change in the environment. Reflecting gene pool may no longer be reflective of the original.
Term
Summary of Genetic Drift (4)
Definition
1. significant in small populations
2. causes allele frequencies to change at random
3. lead to loss of genetic variation within populations
4. cause harmful alleles to become fixed
Term
Gene Flow
Definition
consists of the movement of alleles among populations. Reduce variation among populations over time.
Term
Natural Selection and Adaptive Evolution
Definition
NS consistently causes AE by acting on an organisms phenotype.
Term
Relative Fitness
Definition
contribution an individual makes to the gene pool of the next generation, relative to the contributions of other individuals.
Term
3 Modes of Selection
Definition
Directional, disruptive, stabilizing
Term
Directional Selection
Definition
favors individuals at one end of the phenotypic range
Term
Disruptive Selection
Definition
favors individuals at both extremes of the phenotypic range
Term
Stabilizing Selection
Definition
favors intermediate variants and acts against extreme phenotypes
Term
Adaptive Evolution
Definition
occurs as a match between an organism and its environment increases; because the environment can change, ae is a continuous process.
Term
Neutral Variation
Definition
genetic variation that does not confer a selective advantage or disadvantage
Term
Diploidy (Preservation of Genetic Variation)
Definition
maintains genetic variation in the form of hidden recessive alleles; heterozygotes can carry recessive alleles that are hidden from the effects of selection.
Term
Balancing Selection
Definition
occurs when NS maintains stable frequencies of 2 or more phenotyic forms in a population.
Term
Balancing Selection Includes (2)
Definition
1. heterozygote Advantage
2. Frequency-dependent selection
Term
Heterozygote Advantage
Definition
occurs when heterozygotes have a higher fitness then homozygotes
Term
Frequency-Dependent Selection
Definition
Fitness off a phenotype declines if it becomes too common
Term
Why Doesn't Natural Selection result in "perfection" ? (4)
Definition
1. selection can act only on existing variations
2. Evolution is limited by historical constraints
3. Adaptations are often compromises
4. chance, Natural selection and the environment interact
Term
Speciation
Definition
origin of new species, is at the focal point of evolutionary theory
Term
Evolutional Theory
Definition
must explain how new species originate and how populations evolve
Term
Microevolution
Definition
consists of changes in allele frequency in a population over time
Term
Macroevolution
Definition
refers to broad patterns of evolutionary change above the species level.
Term
Grouping Oganisms
Definition
compare morphology, physiology, biochemistry, and DNA
Term
Biological Species Concept
Definition
states that a species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring; they do not breed successfully with other populations.
Term
Reproductive Isolation
Definition
the existence of biological factors (barriers) that impede two species from producing viable, fertile offspring. Classified by whether factors act before or after fertilization.
Term
Hybrids
Definition
offspring of crosses between different species
Term
Prezygotic (definition and 3 reasons and examples)
Definition
barriers block fertilization from occurring by:
1. impeding different species from attempting to mate
2. Preventing the successful completion of mating
3. Hybrid breakdown
ex) habitat isolation, temporal isolation, behavioral isolation, mechanical isolation, gametic isolation.
Term
Pastzygotic (definition and 3 things)
Definition
barriers prevent the hybrid zygote from developing into a viable, fertile adult:
1. reduced hybrid viability
2. reduced hybrid fertility
3. hybrid breakdown
Term
Limitations of Biological Species Concept (2&example)
Definition
-cannot be applied to fossils or asexual organisms (including prokaryotes)
-emphasizes absence of gene flow; however gene flow can occur between distinct species
ex) grizzly + polar bear = grolar bear
Term
Morphological Species Concept
Definition
defines a species by structural features.
Applied to sexual and asexual species but relies on subjective criteria
Term
Ecological Species Concept
Definition
views a species in terms of ecological niche.
Applies to sexual and asexual species and emphasizes the role of disruptive selection
Term
Phylogenetic Species Concept
Definition
defines a species as the smallest group of individuals as a phylogenetic tree.
Applies to sexual and asexual species, but it can be difficult to determine the degree of difference required for separate species
Term
2 Way Speciation Can Occur:
Definition
Allopatric speciation
sympatric speciation
Term
Allopatric Speciation
Definition
a population forms a new species while geographically isolated from its parent population.
-Gene flow is interrupted or reduced when a population is divided into geographically isolated subpopulations.
Term
Sympatric Speciation
Definition
a subset of a population forms a new species without geographic separation .
-speciation takes place in geographically overlapping populations.
Term
Barriers
Definition
depends on the ability of a population to disperse
ex) canyon-barrier for small rodents, but not birds, coyotes or pollen.
-separate populations may evolve independently through mutations, NS and genetic drift
-regions with many geographical barriers typically have more species that do regions with fewer barriers.
Term
Reproductive Isolation
Definition
may arise as a result of genetic divergence ex)mosquito fish in bahamas comprise seveal isolated populations in different ponds.
-Reproductive isolation between populations general increases as the distance between them increases
Term
Polyploidy
Definition
extra sets of chromosomes due to accidents during cell division, may lead to sympatric speciation
Term
sympatric speciation may result from (2)
Definition
-polyploidy
-appearance of new ecological niches
ex)north american maggot fly can live on native hawthorn trees as well as more recently introduced apple trees
Term
Sexual Selection (sympatric speciation)
Definition
-NS for mating success
-can drive sympatric speciation
ex)sexual selection for mates of different clours has likely contributed to speciation in cichild fish in Lake Victoria
Term
Speciation can be studied Using (3)
Definition
1. fossil records
2. morphological data
3. molecular data
Term
Punctuated Equilibria
Definition
describes periods of apparent stasis punctuated by sudden change.
Niles Eldredge and Stephen Jay Gould
The model contrasts with a model off gradual change in species existence.
Term
Speciation Rates
Definition
can be rapid or slow.
Ranges from 4000 years (some cichlids) to 40 million years (some beetles) with an average off 6.5 million years.
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