Biology Chapter 12: Genetics and Evolution Flashcards

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1
Q

Chromosomes

A

contain genes in a linear sequence

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2
Q

Alleles

A

Alternate forms of a gene

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3
Q

dominant allele

A

masks recessive allele and requires only one copy to be expressed.

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4
Q

Recessive allele

A

Requires two copies to be expressed - masked by a dominant allele

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5
Q

genotpe

A

combination of alleles one has at a given genetic locus.

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6
Q

phenotype

A

observable manifestation of a genotype

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7
Q

Penetrance

A

the proportion of a population with a given genotype.

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8
Q

Medel’s first law of segregation

A

an organism has two alleles for each gene, which segregates during meiosis, resulting in gametes carrying only one allele for a trait.

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9
Q

Mendel’s second law of independent assortment

A

state that the inheritance of one allele does not influence the probability of inheriting a given allele for a different trait.

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10
Q

Griffith experiment

A

demonstrated the transforming principle, converting non-virulent bacteria to virulent bacteria by exposure to heat-killed virulent bacteria.

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11
Q

Avery-MacLeod-McCarthy experiment

A

demonstrated that DNA is the genetic material because degradation of DNA led to a cessation of bacterial transformation

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12
Q

Hershey-Chase

A

confirmed that DNA is the genetic material because only radiolabeled DNA could be found in bacteriophage-infected bacteria.

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13
Q

Gene pool

A

All of the alleles in a given population.

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14
Q

Point mutations

A

substitute one nucleotide for another

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15
Q

Frameshift mutation

A

moving the three letter transcriptional reading frame

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16
Q

Silent mutation

A

no effect on the protein

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17
Q

Missense mutation

A

results in the substitution of one amino acid for another.

18
Q

Nonsense mutation

A

results in the substitution of a stop codon for an amino acid.

19
Q

Frame shift

A

caused by insertions and deletions

20
Q

Translocation

A

a segment of DNA is swapped with a segment of DNA from another chromosome

21
Q

Genetic leakage

A

a flow of genes between species through hybrid offspring

22
Q

Genetic drift

A

occurs when the composition of the gene pool changes as a result of change

23
Q

Founder effect

A

results from bottlenecks that suddenly isolate a small population, leading to inbreeding and increased prevalence of certain homozygous genotypes.

24
Q

Monohybrid cross

A

Accounts for one gene

25
Q

Dihybrid corss

A

Accounts for two genes

26
Q

Recombination frequency

A

the likelihood of the two alleles being separated during crossing over in meiosis. Genetic maps can be makde using recombination frequency as the scale in centimorgans.

27
Q

Hardy-Weinberg principle

A

states that if a population meets certain criteria (aimed at a lack of evolution), then the allele frequencies will remain constant

28
Q

Natural selection

A

States that chance variations exist between individuals and that advantageous variations - those that increase an individuals fitness for the environment - afford the most opportunity for reproductive success

29
Q

Modern synthesis model

A

accounts for mutation and recombination as mechanisms of variation and considers differential reproduction to be the mechanism of reproductive success.

30
Q

Inclusive fitness

A

considers an organism’s success to be based on the number of offspring, success in supporting offspring or relatives ensures continuation of genes in subsequent generations

31
Q

Punctuated equilibrium

A

considers evolution to be a very slow process with intermittent rapid bursts of evolutionary activity.

32
Q

Stabilizing selection

A

keeps phenotypes in a narrow range, excluding extremes

33
Q

Directional selection

A

moves the average phenotype toward one extreme

34
Q

Disruptive selection

A

moves toward two different phenotypes at the extremes and can lead to speciation

35
Q

Adaptive radiation

A

the rapid emergence of multiple species from a common ancestor, each of which occupies its own ecological niche.

36
Q

Species

A

largest group of organisms capable of breeding to form fertile offspring. Species are reproductively isolated from each other by pre- or postzygotic mechanisms.

37
Q

Divergent evolution

A

occurs when two species sharing a common ancestor become more different

38
Q

Parallel evolution

A

occurs when two species sharing a common ancestor evolve in similar ways due to analogous selection pressures.

39
Q

Convergent evolution

A

occurs when two species not sharing a recent ancestor evolve to become more similar due to analogous selection pressures.

40
Q

Molecular clock model

A

the degree of difference in the genome between two species is related to the amount of time since the two species broke off from a common ancestor.