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Biol 450 Modern Genetics Final Exam
Terms in this set (212)
pairing and segration of homologous chromosomes during meiosis 1
What is the mechanism that ensures Mendel's first law (equal segregation of alleles?
A mutant that cannot make its own arginine is called an arginine auxotroph
A mutant strain of Neurospora is described as an arginine auxotroph. What does this mean?
We know that a plant showing a dominant phenotype carries at least one dominant allele (denoted A/-). What is the genotype of the plant that this plant should be crosspollinated with to determine what other allele is (a or a)?
"Enzyme A" is encoded by the "a" gene, and is required to synthesize the bright red pigment. A lack of red pigment results in a brown eye color. You cross two fruit flies who are heterozygous for a recessive mutation that completely inactivates the "a" gene. What proportion of their offspring will have a brown eyes ?
50% will be wild type, 50% will be black
A dominant gene b+ is responsible for the wild-type body color of Drosophila; its recessive allele b produces black body color. A testcross of a heterozygous b+/b female by a black b/b male gave 52 black and 58 wild-type progeny. If a black female from these progeny were crossed with a wild-type brother, what phenotypic ratios would be expected in their offspring?
Crossing over can be followed when it occurs between ________________ carrying two different alleles of two different genes.
A linkage map can not be more than 100 centimorgans.
A mutation occurs in a germ cell of a pure-breeding, wild-type male mouse prior to DNA replication. The mutation is not corrected, and the cell undergoes DNA replication and a normal meiosis producing four gametes. How many of these gametes will carry the mutation?
False (heterogametic is XY)
Females are the heterogametic sex.
He is not the father of the child
In a 1945 trial, a woman accused Charlie Chaplin of fathering her child. The ABO blood types were as follows:
Woman = type A
Child = type B
Charlie Chaplin = type 0.
What conclusion would you make—as a jury member—about this trial?
In hogs, a dominant allele B results in a white belt around the body. At a separate locus, the dominant allele S causes fusion of the two parts of the normally cloven hoof resulting in a condition known as syndactyly. A belted syndactylous sow was crossed to an unbelted cloven-hoofed boar, and in the litter there were:
25% belted syndactylous
25% belted cloven
25% unbelted syndactylous
25% unbelted cloven
The genotypes of the parents can best be represented as which of the following?
determine whether the difference between observed and expected values is significant
A chi square test is used to
Sperm and eggs are _________ cells, which are formed by a specific type of cell division called MEIOSIS.
A null mutation of a haploinsufficent gene would be dominant to wildtype
During DNA replication or s phase
When do chromatids form?
Can we detect crossing over between sister chromatids, or crossing over in homozygotes, when we look at the progeny of a cross?
A recessive X-linked gene mutation is known to generate premature baldness in males but is without effect in women. If a heterozygous female marries an affected male, what proportion of all their children is expected to be prematurely bald?
________________ occurs when the heterozygous F1 progeny perform better than either homozygous parent.
What is the type of cell division that produces identical daughter cells called?
mitosis in somatic cells (non-sexual cells)
Variegated leaves occur when dysfunctional chloroplasts segregate unequally to daughter cells during_________.
How many degrees of freedom are there in a dihybrid self cross of unlinked genes?
Mitosis results in two identical daughter cells
Which of the following is TRUE with respect to haploid and diploid cells?
A. mitosis is simpler in haploid cells than in diploid cells
B. In haploid cells, condensed chromosomes have an "I" shape, while in diploid cells they have an "X" shape.
C.Mitosis results in two identical daughter cells.
D. The process of meiosis is identical in haploid and diploid cells.
A single gene mutation can have multiple effects. For example, there is a recessive allele for coat color in mice called yellow, which also affects viability. This is called:
27.5 map units
in a di hybrid test cross, 110 progeny show a recombinant phenotypes and 290 show parental phenotypes, how far apart are these genes?
recombinant: combination of genes crossing over from homologous chromosomes
Parental: crossing over doesn't occur
He is most likely homozygous brown
In pet rabbits, brown coat color is recessive to black coat color. A black female rabbit gives birth to four black-coated and three brown-coated baby rabbits. What can be deduced about the genotype of the baby rabbits' father?
In a plant in which 2n = 24, what is the total number of chromatids present after s-phase?
"Dumpy" is a commonly used mutant phenotype in the nematode worm C. elegans. Two "Dumpy" individuals are crossed to each other, and this cross produces 210 "Dumpy" and 68 wild-type individuals. If one of the two "Dumpy" individuals used in this cross was mated with a wild type, what "Dumpy": wild-type ratio would we observe in the offspring?
What phenotypic ratio in the progeny of a dihybrid self cross (that deviates from mendel's prediction) is evidence of recessive epistatis?
- where recessive alleles of one locus (a/a) mask phenotypic expression of another locus (B/B, B/b, b/b)
the pairing of homologous chromosomes during meiosis 1
What process occurring during meiosis ensures independent assortment?
small size is dominant to large size, but we can't determine which color is dominant
A plant with small red flowers is crossed to a plant with large white flowers. The resulting F1 is composed of 75 plants with small red flowers and 72 plants with small white flowers.
If flower color and flower size are controlled by a single gene each, what can be concluded from these results?
chiasmata; Meiosis 1
Chiasmata: point at which paired chromosome remains in contact during 1st metaphase
Alleles of linked genes recombine at ________ during _________:
A very common type of red-green colorblindness in humans is caused by a mutation in a gene located on the X chromosome. Knowing that the mutant allele is recessive to the wild type, what is the probability of woman with normal vision having colorblind son, if her father is colorblind?
What types of cells undergo meiosis
If genes assort independently, a testcrossed dihybrid characteristically produces progeny phenotypes in the ratio
You are studying meiosis in fungi with an organism in which the haploid chromosome number is 5 (n = 5). You combine two haploid cells together (strain 1 by strain 2), and then activate meiosis to regenerate haploid cells. What are the odds that any individual haploid cell will have either the five chromosomes from strain 1 or the five chromosomes from strain 2?
18 replicated chromosomes, & a total of 36 chromatids
Meiosis I is about to start in a cell of a plant in which 2n = 18. At this stage, the cell has:
homologous pairs/homologous chromosomes/homologs
What separates during meiosis 1?
Fruit color in a particular plant is controlled by a set of three QTLs (quantitative trait loci, or "polygenes") that work in an equal and additive manner. Each QTL has two alleles (i.e., A and a); each allele represented by a capital letter produces one dose of yellow pigment, while alleles represented with lower case letters do not produce any pigment at all.
Assuming no effects by the environment, how many different shades of yellow fruit color are there?
Males display the phenotype associated with any given alleles of a gene located on the X because they are
If mutant 1 complements mutant 2, and mutant 2 complements mutant 3, but mutant 3 fails to complement mutant 1, how many genes have been identified by these 3 mutations?
& @ * $
Mutant $ & * @
IL-1 + - + -
IL-2 + - + +
IL-3 + - - -
A biologist studying amino acid synthesis in Neurospora discovered that threonine can be converted into isoleucine. To understand the metabolic pathway involved, the biologist made mutants that can't grow in the absence of isoleucine. To determine the order of steps in the pathway, the biologist supplied intermediate compounds, and checked for growth. (In the table below, + means growth, - means no growth.) Use the data in the table above to determine the order of intermediate compounds in the pathway:
A null mutation of a haplosufficient gene would be recessive to wildtype.
What phenotypic ratio in the progeny of a dihybrid self cross (that deviates from mendel's prediction) is evidence of dominant epistatis?
Dominant epistasis: a dominant allele that masks the expression of another dominant allele , other dominant only exhibits if 1st allele is recessive
80 DNA molecules & 40 replicated chromosomes
Mice (Mus musculus) have 40 chromosomes per diploid cell (2n = 40). How many double-stranded DNA molecules and how many chromosomes are there in a mouse cell that is ready to divide?
If a plant of genotype A/a is selfed, and numerous offspring are scored, what proportion of the progeny is expected to have homozygous genotypes?
For linked genes, recombinant gametes form more often than parental gametes
We discussed many genes interactions that produce deviations from the classic dihybrid ratio. Which of the following ratios is most likely due to interactions between genes in the same pathway?
there is no precurcer
A mutation in a gene that functions in a metabolic pathway can cause disease because______________.
Watson and Crick discovered the structure of the DNA double helix, they immediately noticed that the structure itself suggested the ____________mode of replication.
helps position the ribosome in prokaryotic translation.
The Shine-Delgarno sequence ____________.
hydrogen bonds between neighboring amino acids
What type of bonds hold alpha helical structures together in a protein?
A peptide bond is formed
What happens when charged amino acids are bound to the A and P sites in a ribosome?
Transcription and translation are coupled in______________.
It only regulates the trp operon
depend on fact that transcription is coupled to translation in prokaryotes
position of the ribosome in the leader sequence determines 3D shape of mRNA
Leader peptide senses whether there is enough of the specific amino acid available for growth
Which of the following is not true about attenuation?
wobble, 1, up to 3
Due to ________, _____ tRNA(s) can pair or hydrogen bond with ______ codon(s).
As ________ uncoils the double helix at the replication fork, _________ relieves the supercoiling that builds up in front of the replication fork.
All the other answers are true
What would we expect to find in an E. coli cell whose environment contains lactose but no glucose?
A. Lactose bound to the repressor protein
B. Abundant Lac mRNA
C. high levels of cAMP
D. CAP/camp activator bound to the promoter of the lac operon.
E. All the other answers are true.
complete a transesterification reaction during splicing in eukaryotes
It's a good thing the 2' carbon is hydroxylated in RNA. This hydroxyl group is needed to_________________.
If a doublestranded DNA molecule contains 30% Adenine, how much Guanine does it contain?
Which polymerase does not require a template strand?
does not exist
A tRNA that recognizes the stop codon UAA________.
The decoding center and the peptidyl-transferase center in the ribosome are composed of
Heat killed S-strain extract treated with DNAse, mixed with R strain
Which mixture of Streptococcus pneumoniae, when injected into mice, does not kill them?
uracil replaces thymine and the 2' carbon contains a hydroxyl group
The structure of RNA differs from DNA in that___________.
each regulate several target genes
Although very different in molecular function, miRNAs in eukaryotes, and sigma factors in prokaryotes_____________________.
A string of UUUUUs is transcribed into the mRNA destabilizing the complex, and then the polymerase backs into a CG hairpin and the transcription complex falls apart.
Transcription can terminate in prokaryotes if___________________.
two sister chromatids in an eukaryote
DNA replication results in_________________.
cotranscriptional, 5', poly A tail, 3'
During__________________ processing, a cap is added to the ______ end of the mRNA, and a __________________is added to the _________ end.
5'-3' exonuclease, remove, 3'-5' exonuclease, remove
DNA polymerase I contains ___________________ activity to ______________nucleotides in the Okazaki fragment, and __________ activity to _________ an incorrectly added nucleotide.
Catabolic repression of the lac operon by glucose actually works through______________________.
They are harder to replicate than G/C rich regions
Which of the following is not true about A/T rich regions in a DNA double helix ______________.
the template is read from 3' to 5'
How is transcription similar to replication?
initiation, elongation, termination
What are the three basic steps of transcription in prokaryotes and eukaryotes?
If an Adenine hydrogen bonded with a Gaunine the diameter of the DNA double helix would be __________.
There are _________aminoacyl tRNA synthetases, but __________tRNAs
a. 20, not as many
b. 20, more
c. 64, not as many
d. 64, also 64
Which of the following can function as an effector?
activator, bound, repressor, removed
In positive regulation an _____________is__________to induce transcription, while in negative regulation a ____________ is ___________ to repress transcription.
amino, collinear, 5'
The ______ end of a protein is __________ with the ________ end of the mRNA that encodes it
a. 3'; identical; carboxy
b. amino; collinear; carboxyl
c. amino; collinear; 5'
d. carboxl; symmetrical; 5'
2, away from
In a replicating bacterial chromosome, there are __________ replication forks moving ________ one another.
a. 4. away from
b. 2, towards
c. 4, towards
d. 2, away from
short RNA, several hundred repeats
Telomerase contains a _______ that acts as a template to add ____________ to the ends of chromosomes.
a. small peptide, a few repeats
b. short DNA, several hundred repeats
c. short RNA, several hundred repeats
d. long RNA, a few repeats
all of the other answers are possible functions of a gene that does not encode a protein
What is a possible function of a gene that does not encode a protein?
a. It encodes a tRNA
b. it encodes an snRNA
c. It encodes a micro RNA
d. all of the other answers are possible functions of a gene that does not encode a protein
Expression of Z is inducible, expression of Y is constitutive
inducible: responds to environmental stimuli or dependent on position in cell cycle
constitutive: transcribed at a constant level
If bacteria are partial diploids of genotype
I+ P+ O+ Z+ Y+/ I- P+ Oc Z- Y+ will the structural genes Z and Y be expressed?
capping enzymes, phosphorylated carboxy
______ __________ interact with the _________ ___________ terminal domain of the RNA polymerase to protect the 5' end of a eukaryotic mRNA, during its precarious journey to the cytoplasm.
It starts to assemble at the 5' cap on the mRNA and starts scanning for AUG
How does a ribosome know where to position itself to start translation in a eukaryote?
DNA polymerase 1, DNA ligase
Okazaki fragments are removed by __________ and the last phosphodiester bond is made by _____________.
Arabinose is bound to AraC protein at the ara I regulatory site, activating transcription.
What happens when bacteria are incubated on arabinose as the only carbon source?
5' UACUCGACUG 3'
If a DNA template strand is 3' ATGAGCTGAC 5', what is the sequence the of transcribed mRNA?
2 leading, towards, replication fork
In a replication bubble, there are ___________ strands that are headed __________ the _________ .
What targets a protein for degradation?
The __________sugar phosphate backbone of a nucleic acid is held together by ___________ bonds.
Alternative splicing, or differential splicing, is a regulated process during gene expression that results in a single gene coding for multiple proteins
In eukaryotes, different proteins can be produce from the same gene by ______.
__________ factors localize RNA polymerase in bacteria, while ______ localizes RNA polymerase in eukaryotes.
Which of the following enzymes or enzyme complexes is not important for mRNA processing?
Which enzyme does not need a template?
How many amino acids are encoded in this partial mRNA AUGCCCGAAUUGAUUAG ?
RNA is the intermediate between DNA and protein
What was the conclusion of the pulse-chase experiment in eukaryotic cells?
a. translation and transcription are coupled.
b. RNA is different from DNA.
c. DNA is the heritable material.
d. RNA is the intermediate between DNA and protein.
No, the genes will not be transcribed
Consider bacterial partial diploids of genotype Is P+ O+ Z- Y-/ F' I- P- O^c Z+ Y- . Will the structural genes Z and Y be expressed?
All statements are incorrect
Which of following statements about the human genome is (are) incorrect?
A. the exons of human genes are, on average, much larger than the introns of human genes
B. less than 3% of the human genome is made up of repetitive sequences such as transposable elements
C. the human genome does not contain pseudogenes
D. all statements are incorrect
You are annotating a region of the fruit fly genome. The bioinformatics tool you're using identifies a potential open reading frame that is 180 bp in length. This open reading frame could potentially encode up to ________ amino acids in a row.
The same base pair multiple times
The term 'sequencing coverage' (e.g., 3X coverage, 20X coverage), when applied in a genomics context, refers to sequencing
a. the same gene in multiple individuals
b. the same base pair multiple times
c. every base pair on the autosomes
d. the same gene in multiple species
A set of overlapping sequences is known as a____________.
phenocopying and targeted mutagenesis
Which of the following are methods of reverse genetics?
A. phenocopying, targeted mutagenesis and phylogenetic analysis
B. phenocopying only
C. phylogenetic analysis only
D. targeted mutagenesis only
E. phenocopying and targeted mutagenesis
You are studying a protein that can activate transcription of gene X by binding to a regulatory sequence upstream of gene X. You are trying to determine the precise sequence identity of this regulatory sequence. Of the experimental tools indicated below, which would best facilitate your efforts?
What is conserved synteny?
This question provides you with an answer and requires you choose the best question.
Answer: Where two species (together with their common ancestor) share chromosomal structural patterns in which chromosomal blocks possess the same genes in the same order.
A. What are caseins?
B. What are orthologs?
C. What is phylogenetic inference?
D. What is conserved synteny?
E. What is parsimony?
The full sequence composition of a gene's introns can be determined from that gene's cDNA
Which of the following statements about cDNA is incorrect?
A. the full sequence composition of a gene's introns can be determined from that gene's cDNA
B. a comparison of cDNA to the corresponding gene in genomic DNA can help determine the boundaries between exons and introns
C. cDNA sequences can be used to verify protein coding genes predicted by bioinformatics tools in analyses of whole-genome sequence data
D. cDNA can be generated by reverse transcribing mRNA
TEs that insert into pi-clusters enable the host genome to target those TE variants genome-wide for inactivation
Which of the following statements about pi-clusters in animal systems such as mammals and Drosophila is correct?
A. TEs that insert into pi-clusters enable the host genome to target those TE variants genome-wide for inactivation
B. All active TEs in a genome must have at least some copies inserted into pi-clusters
C. pi-clusters enabled discovery that retrotransposons mobilize via an RNA intermediate.
D. TEs that insert into pi-clusters form dsRNA molecules via 'readthrough' transcription
Which of the following best describes the C - value paradox?
A.genome size is correlated with the complexity of an organism: more complex organisms typically have larger genomes and less complex organisms typically have smaller genomes
B.genome size is not correlated with the complexity of an organism: more complex organisms can have large or small genomes and less complex organisms can have large or small genomes
C.genome size is correlated with the complexity of an organism: more complex organisms typically have smaller genomes and less complex organisms typically have larger genomes
A negative consequence of transposable element activity for the host genome can be the mutagenic effects of new transposable element insertions. In Drosophila, the R1 and R2 LINE elements preferentially insert into the genes encoding ribosomal RNA. These genes are found in long tandem arrays on the chromosome. The preferential insertion of R1 and R2 LINE elements into these ribosomal RNA genes tends not to have a highly deleterious effect on the host because
A. ribosomal RNA genes have large promoters, and TE insertions into promoter regions is tolerated by the host
B. ribosomal RNA genes consist almost entirely of introns, and TE insertions into introns is tolerated by the host
C. most ribosomal RNA genes are actually pseudogenes
D. the long tandem arrays of ribosomal RNA genes typically consist of many copies, and insertions into some of these copies is tolerated by the host
class 2 is cut-and-paste
The Class ______ transposable elements typically comprise the largest fraction of eukaryotic genomes because their ______ mode of transposition enables them to become more abundant
Replicative transposition in bacteria involves transposition via an RNA intermediate.
Large pigmented spots on corn kernels result from __________ events of either Ac or Ds elements into (out of) the C gene __________ during kernel development.
transposase; different DNA transposon
For nonautonomous DNA transposons to be mobile, they require a functional __________ enzyme encoded by a __________.
transposase, different DNA transposon
For nonautonomous DNA transposons to be mobile, they require a functional __________ enzyme encoded by a __________.
the mRNAs produced by active transposable elements
The RNAi pathway can serve as a transposable element suppression mechanism by degrading__________.
translation DNA sysnthesis
Which of the following DNA repair mechanisms would be considered error-prone?
A. nucleotide excision repair
B. base excision repair
C. translation DNA synthesis
D. synthesis-dependent strand annealing
nonsynonymous and non-conservative
In a specific mutation, one codon is changed from GAA to GTA, causing glutamic acid to be substituted for valine. These amino acids are chemically dissimilar. This mutation would be classified as_____________________.
synthesis-dependent strand annealing (SDSA)
A displacement loop (D-loop) is most likely to form during
The Luria and Delbruck fluctuation test demonstrated that mutations in E. coli that convey resistance to T1 phage occur in response to exposure of E. coli to the T1 phage.
elevated levels of trinucleotide repeats
In humans, Fragile X syndrome is caused by _________.
-Occur when length difference between two alleles is unknown due to insertions and delections
Frameshifts are most likely to occur because of________.
intercalating agents; INDEL
Proflavin and ICR-191 are ___________ that can cause ___________ mutations.
a bivalent plus a univalent A bivalent: pair of homologous chromosomes Univalent: a single chromosome
Which of the following is not a chromosome pairing possibility in an autotetraploid? autotetraploid. : an individual or strain whose chromosome complement consists of four copies of a single genome due to doubling of an ancestral chromosome complement.
paracentric inversion heterozygote
Dicentric bridges and acentric fragments are produced during meiosis in a(n)________________.
Allopolyploids possess homeologous chromosome sets that originate from individuals of different species.
2n+1 and 2n-1
Which of the following chromosomal designations would be considered aneuploidy?
An organism that is trisomic would be best described by which the following chromosomal constitutions? where there are three instances of a chromosome instead of normal two (ex. down's syndrome)
A wild type chromosome has the structure CDEF
GHIJKL, where the asterisk (
) represents the position of the centromere.
Which of the following best describes a paracentric inversion (inversions that do not include centromere (o))?
A child with Turner Syndrome is found to be colorblind (an X linked recessive trait). The child's mother and father both have a normal chromosome number and have normal vision (i.e., are not colorblind). The sex chromosome number makeup of this child is _________. The nondisjunction event that produced the abnormal gamete resulting in the child with Turner Syndrome must have occurred in her _________.
In Drosophila, individual X-linked genes are expressed at an approximately 2-fold higher level in males versus in females. A consequence of this is that X-linked genes are expressed at similar levels in males (XY) and females (XX). This phenomenon is known as________________.
Inversions and translocations; duplications and deletions
_____________ are classified as balanced chromosomal rearrangements whereas _____________ are classified as unbalanced chromosomal rearrangements.
broad-sense heritability (H^2)
Vg/Vx=Vg/Vg+Ve or H^2=Vg/Vx
The proportion of total phenotypic variance at the population level that is contributed by genetic variance
the fraction of the total phenotypic variance that is attributable to genetic variation
exhibit continuous variation that are influenced by multiple genes and by the environment
interaction among alleles at a locus, major part of narrow-sense heritability
narrow-sense heritability (h^2)
The proportion of phenotypic variance that can be attributed to additive genetic variance
Additive gene action
When the trait value for the heterozygous class at a QTL is exactly intermediate between the trait values for the two homozygous classes.
Dominant gene action
The situation when the trait value for the heterozygous class at a QTL is equal to the trait value for one of the two homozygous classes.
Gene action under which the phenotype of heterozygotes is intermediate between the two homozygotes but more similar to that of one homozygote than the other.
Additive Effect (A)
Half the difference between the mean of the phenotypic values for the homozygous genotypic classes at a QTL.
A=Xb2b2- Xb1b1/ 2
Dominance Effect (D)
The difference between the trait value for the heterozygous class at a QTL and the midpoint between the trait values of the two homozygous classes.
Artificial Selection (Domestication)
practice of selective breeding to aquire more "desirable" traits
Selection differential (S)
The difference between the mean of a population and the mean of the individual members selected to be parents of the next generation.
The amount of change in the average value of some phenotypic character between the parental generation and the offspring generation as a result of the selection of parents.
R=h^2S, artificial selection is influenced by heritability
Quantitative trait locus (QTL)
region of the genome harboring a gene(s) that influence(s) variation in a given trait
A method for locating QTL in the genome and characterizing the effects of QTL on trait variation.
linkage disequilibrium (LD)
nonrandom association between two loci/alleles
genetic variance (g)
The part of the phenotypic variation among individuals in a population that is due to the genetic differences among the individuals
environmental variance (e)
The part of the phenotypic variation among individuals in a population that is due to the different environments the individuals have experienced.
leaves a distinct signature at sequence level which reduces genetic variation at and around the site of selction
number of QTLs influencing variation in a trait, approximate locations on chromosomes, effects on the trait, and actions
uses naturally occurring linkage disequilibrium to find QTL in natural populations,
designated location on a chromosome where gene is located
Single nucleotide polymorphisms (SNPs)
A nucleotide-pair difference at a given location in the genomes of two or more naturally occurring individuals.
A locus composed of several to many copies (repeats) of a short (about 2 to 6 bp) sequence motif. Different alleles have different numbers of repeats.
A single nucleotide polymorphism (SNP) for which the less common allele occurs at a frequency of about 5 percent or greater.
A single nucleotide polymorphism (SNP) for which the less common allele occurs at a frequency below 5 percent.
unique combination of alleles at multiple loci on the same chromosome
Hardy-Weinberg Law (HWE)
An equation used to describe the relationship between allele and genotypic frequencies in a random-mating population.
The sum total of all alleles in the breeding members of a population at a given time.
The proportion of individuals in a population having a particular genotype.
A measure of the commonness of an allele in a population; the proportion of all alleles of that gene in the population that are of this specific type.
Hardy-Weinberg Equation (HWE)
The stable frequency distribution of genotypes A/A, A/a, and a/a, in the proportions of p^2, 2pq, and q^2, respectively (where p and q are the frequencies of the alleles A and a), that is a consequence of random mating in the absence of mutation, migration, natural selection, or random drift.
Having only a single copy of a gene instead of the customary two copies. All the genes on the single X chromosome in the male are 'hemizygous'.
positive assortative mating
like mates with likes, increases homozygosity
negative assortative mating
like mates with unlike, increases heterozygosity
isolation by distance
A bias in mate choice that arises from the amount of geographic distance between individuals, causing individuals to be more apt to mate with a neighbor than another member of their species farther away.
The division of a species or population into multiple genetically distinct subpopulations
mating with relatives, increases homozygosity
Identical By descent (IBD)
When two copies of a gene in an individual trace back to the same copy in an ancestor.
Inbreeding Coefficient (F)
The probability that the two alleles at a locus in an individual are identical by descent., two alleles can be traced back to a common ancestor
F=(1/2)^n n=number of individuals in a loop
An allele for which all members of the population under study are homozygous, and so no other alleles for this locus exist in the population.
Segregating Sites (S)
The number of variable or polymorphic nucleotide sites in a set of homologous DNA sequences.
mutation rate (µ)
The probability that a copy of an allele changes to some other allele form in one generation.
migration/ gene flow
The movement of individuals (or gametes) between populations.
ultimate source of all genetic variation, can add variation to a population via gene flow from another population
random fluctuation in allele frequencies due to 'chance' events
genetic drift inversely proportional to population size
genetic drift has weaker effects in larger populations
has stronger effects in larger populations
A perfect fit of haplotype frequencies in a population to the frequencies expected if the alleles at the loci defining the haplotypes are associated at random.
Deviation in the frequencies of different haplotypes in a population from the frequencies expected if the alleles at the loci defining the haplotypes are associated at random.
new mutations arise on a single haplotype
will decay over time because of recombination
nonadaptive evolutionary changes due to genetic drift
An allele that has no effect on the fitness of individuals that possess it
The constant rate of substitution of amino acids in proteins or nucleotides in nucleic acids over long evolutionary time.
substitution rate: k=2Nu*1/2N=u
A random difference in the frequency of an allele or a genotype in a new colony as compared to the parental population that results from a small number of founders.
Genetic diversity reduced in populations that have experienced founder effect
initial frequency of a new mutation
Probability of loss
differential rates of survival and reproduction among different individuals or genotypes
ability to survive and reproduce
absolute fitness (W)
the number of offspring per individual or genotype
A measure of the fitness of an individual or genotype relative to some other individual or genotype, usually the most fit individual or genotype in the population.
Selection that changes the frequency of an allele in a constant direction, either toward or away from fixation for that allele.
The process by which a favorable allele is brought to a higher frequency in a population because individuals carrying that allele have more viable offspring than other individuals.
a favorable allele reaches fixation in a population
Natural selection that removes deleterious variants of a DNA or protein sequence, thus reducing genetic diversity.
Natural selection that results in an equilibrium with intermediate allele frequencies, produces increased genetic variation in and around the site of selection
continuous heritable change within & between lines of descent, all organisms related through descent from common ancestor
Principle of variation
among individual members of a population there is variation in morphology, physiology, behavior, etc.
Principle of heredity
offspring resemble parents more than they resemble unrelated individuals due to shared genes
Principle of selection
variants that are more successful at surviving and reproducing in a given environment, produce more offspring
A mutation that changes one codon for an amino acid into another codon for that same amino acid. Also called silent mutation.
no change in amino acid, neutral alleles, diverge faster than nonsynonymous
A change in the DNA of a protein-coding sequence that causes an amino acid change.
changes amino acid, more likely to be deleterious
protein rate of evolution
rate is dependent on function of protein & tolerance of amino acid change
The situation when natural selection promotes multiple substitutions that alter the function of a protein or regulatory element through repeated rounds of mutation and selection.
can drive the fixation of many changes in evolving molecules
mutation & natural slection
The dependency of the fitness advantage or disadvantage of a new mutation on the mutations that have been previously fixed.
fixed differences only drift, process is slow
attributable to drift and/or selection, lead to more rapid substitutions
mutations are in different genes
mutations are in the same gene
nucleotide differences among individuals within each species
fitness dependent on immediate selective conditions, trait that may be beneficial in one environment may be deleterious in another
P element suppression
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