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Biology Kaplan MCAT > Ch. 12: Genetics and Evolution > Flashcards

Ch. 12: Genetics and Evolution Flashcards

1
Q

Chromosomes

A

Contain genes in a linear sequence

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2
Q

Alleles

A

Alternative forms of a gene

  • Dominant allele: requires only one copy to be expressed
  • Recessive allele: requires two copies to be expressed
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3
Q

Genotype

A

Combination of alleles one has at a given genetic locus

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4
Q

Homozygous

A

Having two of the same allele

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5
Q

Heterozygous

A

Have two diff alleles

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6
Q

Hemizygous

A

Having only one allele (such as male sex chromosomes)

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7
Q

Phenotype

A

observable manifestation of a genotype

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8
Q

Complete dominance

A

Has one dominant allele and one recessive allele

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9
Q

Codominance

A

Has more than one dominant allele

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10
Q

Incomplete dominance

A

Has no dominant alleles; heterozygotes have intermediate phenotypes

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11
Q

Penetrance

A

The proportion of a population with a given genotype who express the phenotype

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12
Q

Expressivity

A

Varying phenotypic manifestations of a given genotype

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13
Q

Mendel’s laws:

A

Help explain inheritance of genes from parent to offspring

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14
Q

Mendel’s first law

A

Law of segregation: states that an organism has 2 alleles for each gene, which segregate during meiosis, resulting in gametes carrying only one allele for a trait

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15
Q

Mendel’s second law

A

Law of independent assortment: states that the inheritance of one allele does not influence the probability of inheriting a given allele for a diff trait

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16
Q

DNA as genetic material experiments

A

Griffith experiment: demonstrated that transforming principle, converting non-virulent bacteria into virulent bacteria by exposure to heat-killed virulent bacteria
Avery-MacLeod-McCarty: experiment demonstrated that DNA is the genetic material because degradation of DNA led to a cessation of bacterial transformation
Hershey-Chase: experiment confirmed that DNA is the genetic material bc only radiolabeled DNA could be found in bacteriophage- infected bacteria

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17
Q

Gene pool

A

All of the alleles in a given population

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18
Q

Mutations:

A

changes in DNA sequence

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19
Q

Point mutations

A

Substituting of one nucleotide for another

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20
Q

Frameshift mutations

A

Moving the three-letter transcriptional reading frame

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21
Q

Silent mutation

A

has no effect on the protein

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22
Q

Missense mutation

A

Results in the substitution of one amino acid for another

23
Q

Nonsense mutation

A

Results in the substitution of a stop codon for an amino acid

24
Q

Insertions and Deletions

A

Result in a shift in the reading frame, leading to changes for all downstream amino acids

25
Deletion mutation
Occur when a large segment of DNA is lost
26
Duplication mutation
Occur when a segment of DNA is copied multiple times
27
Inversion mutations
Occur when a segment of DNA is reversed
28
Insertion mutations
Occur when a segment of DNA is moved from one chromosome to another
29
Translocation mutation
Occur when a segment of DNA is swapped w a segment of DNA from another chromosome
30
Genetic leakage
Flow of genes between species through hybrid offspring
31
Genetic drift
Occurs when the composition of the gene pool changes as a result of chance
32
Founder effect
Results from bottlenecks that suddenly isolate a small population, leading to inbreeding and increased prevalence of certain homozygous genotypes
33
Punnett Squares
Visually represent the crossing of gametes from parents to show relative genotypic and phenotypic frequencies
34
Parent generation
Represented by P
35
Filial generations
Offspring, represented by F1, F2, and so on in sequence
36
Monohybrid Cross
Accounts for one gene
37
Dihybrid Cross
Accounts for two genes
38
Sex-linked crosses
Sex chromosomes are usually used to indicate sex as well as genotype
39
Recombination Frequency
Theta, is the likelihood of two alleles being separated during crossing over in meiosis
40
Genetic maps
Can be made using recombination frequency as the scale in centimorgans
41
Hardy-Weinberg Principle
States that if a population meets certain criteria (aimed at lack of evolution), the then the allele frequencies will remain constant (Hardy-Weinberg equilibrium)
42
Natural Selection
States that chance variations exist between individuals and that advantageous variations- those that increase an individual’s fitness for the environment- afford the most opportunity for reproductive success
43
Modern synthesis model (neo-Darwinism)
Accounts for mutation and recombination as mechanisms of variation and considers differential reproduction to be the mechanism of reproductive success
44
Inclusive Fitness
Considers an organism's success to be based on the number of offspring, and the ability of the offspring to then support others; survival of offspring or relatives ensures continuation of genes in subsequent generations
45
punctuated equilibrium
Considers evolution to be a very slow process with intermittent rapid bursts of evolutionary activity
46
Different types of selection:
Lead to changes in phenotypes
47
Stabilizing selection
keeps phenotypes in a narrow range, excluding extreme
48
Directional Selection
Moves the average phenotype toward one extreme
49
Disruptive selection
Moves toward 2 diff phenotypes at the extremes and can lead to speciation
50
Adaptive radiation
Is the rapid emergence of multiple species from a common ancestor, each of which occupies its own ecological niche
51
Species
The largest group of organisms capable of breeding to form fertile offspring
52
Reproductively isolated
Species are reproductively isolated from each other by pre- or postzygotic mechanisms
53
Two species can evolve w different relationship patterns
- Divergent evolution: occurs when two species sharing a common ancestor become more different - Parallel evolution: occurs when two species sharing a common ancestor evolve in a similar ways due to analogous selection pressure - Convergent evolution: occurs when two species not sharing a recent ancestor evolve to become more similar due to analogous selection pressures
54
Molecular clock model
The degree of diff in the genome between two species is related to the amount of time since the two species broke off from a common ancestor

Biology Kaplan MCAT (12 decks)

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