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Genetics Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Homologues

A

analogous of chromosomes (i.e. humans have 23 homologous pairs), one from each parent

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2
Q

Locus

A

location of a gene on a chromosome

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3
Q

Homozygous

A

both alleles are the same for a gene

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4
Q

Heterozygous

A

alleles are different for a gene

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5
Q

Hemizygous

A

there’s only 1 allele present (i.e. X chromosome in males)

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6
Q

Codominance

A

when more than 1 dominant allele exists for a given gene

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7
Q

Incomplete dominance

A

NEITHER of the 2 alleles present is dominant; a heterozygote expresses a phenotype that is intermediate between 2 homozygous phenotypes

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8
Q

Multiple alleles

A

a gene controlled by more than 2 alleles

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9
Q

Pleiotropy

A

When one gene affects multiple characteristics

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10
Q

Lethal allele

A

allele that results in the death of an individual

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11
Q

polygenic trait

A

traits that are controlled by multiple genes, traits often form a phenotypic spectrum rather than clear cut categories

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12
Q

Penetrance

A

the % of people that carry the allele (genotype) and actually express the phenotype.

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13
Q

Constant Expressivity

A

the population carrying the allele in their genotype will show the same symptoms and have the same phenotype.

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14
Q

Variable Expressivity

A

the population carrying the allele in their genotype will show variable symptoms and have different phenotype.

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15
Q

Mendel’s first law

A

law of segregation; the two alleles that compose the gene segregate during Anaphase I of meiosis (each gamete is 1n for each inherited traits)

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16
Q

Mendel’s second law

A

Law of Independent Assortment; Inheritance of 1 gene doesn’t affect the inheritance of another gene i.e. Prophase I of meiosis, tetrads of homologous chromosomes (4 sister chromatids) are split randomly (as well as the recombinations during Prophase I between homologous chromosomes (crossing-over)

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17
Q

the Griffith Experiment

A

the hypothesis that a “transforming principle” was responsible for R bacteria to acquire virulence from heat-killed S bacteria.

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18
Q

the Avery, Macleod, and McCarthy

A

determined that this substance was DNA. Only when adding DNAase to the extract and adding it to live R bacteria did no transformation happen. Proving DNA was the transforming substance.

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19
Q

The Hershey-Chase experiment (1952)

A

Radiolabeled one group of bacteriophage’s proteins and another’s DNA. Since they leave their capsid outside the host cell, there were no proteins inside the host and radiolabeled DNA reproduced (radiolabeled proteins did not reproduced).

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20
Q

the Wobble hypothesis

A
  • the redundancy of the genetic code, degenerate
  • multiple codon can code for the same AA (usually at the third position; the wobble position)
  • makes it harder for mutations to have serious effects , mutations on the third position of the codon are silent/degenerate.
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21
Q

Silent nucleotide mutations

A

mutation that occured at the wobble position that has no effect on the occuring AA sequence

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22
Q

missense nucleotide mutations

A

mutation that occured caused a change in one AA in the sequence

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23
Q

nonsense nucleotide mutations

A

mutation that occured coded for a stop codon and stopped the translation

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24
Q

frameshift nucleotide mutations

A

mutation consisted of the deletion/insertion of one AA and caused a shift in the reading frame causing multiple AA changes

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25
Q

chromosomal mutations (5)

A
  • deletion
  • inversion
  • insertion
  • translocation
  • duplication
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26
Q

Mutagen

A

agent that can cause a mutation

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27
Q

carcinogen

A

agent that can cause cancer

28
Q

Mutagenesis

A

processes that result in genetic change

29
Q

carcinogenesis

A

processes of tumor development) may result from mutagenic events

30
Q

Genetic leakage

A

flow of genes between species

31
Q

hybridization

A

an example of genetic leakage, when two different species produce a hybrid offspring.

32
Q

Genetic drift

A

changes in genetic pool due to chance (mutations, homozygosity)

33
Q

Founder effect

A

when the first organism that arrives in an area influences the environment that favors their own survival, at the exclusion of other species.

34
Q

inbreeding depression

A

loss of genetic variation reduces the evolutionary fitness of the population.

35
Q

outbreeding

A

the introduction of unrelated individuals into breeding group and increases the variation in the gene pool.

36
Q

crossing over

A

a type of genetic recombination, occurs during synapsis in metaphase 1. chromatids of homologous chromosomes (not sister chromatids) can have cross overs and exchange pieces of DNA.

37
Q

Test crosses or back crosses

A

an unknown genotype is crossed with homozygous recessive organism to identify the unknown genotype of the organism.

38
Q

Monohybrid cross

A

one trait is being studied

39
Q

Dihybrid cross

A

2 different genes are being studied

40
Q

Heterozygotes in a monohybrid cross will produce

A

genotype: 1:2:1

Phenotype 3:1

41
Q

Heterozygotes in a dihybrid cross will produce

A

phenotype 9:3:3:1

42
Q

Gene mapping

A

despite the 2nd law of Mendel, genes that are physically close to each other will have less chances of being separated.

43
Q

the recombination frequency

A

the probability of two genes being separated is equal to the distance between these two genes. 1% = 1 map unit = 1 centimorgan

44
Q

Hardy Weinberg principle

A

Allele frequence, how often a genotype appears in a population following the Hardy Weinberg Equilibrium

45
Q

Hardy Weinberg equilibrium

A

when a gene pool is stable, gene frequency is not changing and evolution is not occuring

46
Q

Hardy Weinburg rules

A

1- population is very large, no genetic drift
2- no mutations that affect the gene pool
3- no sexual selection, mating is random
4- no migration into or out of the population
5- the genes of the population are all successfully capable of reproduction

47
Q

What is the allele frequency equation?

A

p + q = 1 (p being the total number of dominant alleles and q the total number of recessive alleles)

48
Q

what is the genotypes and phenotypes frequency equation?

A

p² + 2 p q + q² (q² being q.q or the frequency of having both recessive alleles and same goes for p)

49
Q

Natural selection

A

a mechanism for evolution, not evolution itself. Th survival of the fittest and the traits that help species survive in an environment are passed down.

50
Q

Darwinism

A

evolution of species occurs gradually over time and doesn’t take into consideration genetics (recombination, mutations)

51
Q

Neo-darwinism

A

modern synthesis model; includes knowledge of genetics, favorable traits arise from mutations.

52
Q

inclusive fitness

A

reproductive success of an organism is not only due to the number of offspring but also the ability to care for young (than can then take care of others). it explains changes not only at the individual level but also for the species and related individuals.

53
Q

Punctuated equilibrium

A

for some species, little evolution occurs which is interrupted by rapid bursts of evolutionary change.

54
Q

Patterns of selections

A

stabilizing selection
directional selection
Disruptive selection

55
Q

Stabilizing selection

A

loss of extremes and stabilizes phenotypes in a specific range (fetus birth size)

56
Q

Directional selection

A

adaptive pressure that pushes toward dominance of an initially extreme phenotype (antibiotic resistant bacteria only will survive, shifting the dominance toward the acquisition of this resistance)

57
Q

Disruptive selection

A

2 extremes phenotypes are selected over the norm (small and large beaks over normal beaks due to type of food available).

58
Q

Speciation

A

new specis form when an initial species is separated into groups each of which undergo a different set of adaptive changes based on the surrounding environment.

59
Q

reproductive isolation

A

prevents species from mating with others. can be done through prezygotic mechanisms and postzygotic mechanisms

60
Q

prezygotic mechanisms

A

ecological isolations, behavioural isolations

61
Q

postzygotic mechanisms

A

allow for gamete fusion but offspring is inviable or infertile.

62
Q

patterns of evolution

A

divergent evolution
parallel evolution
convergent evolution

63
Q

Divergent evolution

A

two species with a common ancestor but less similar due to environmental pressures

64
Q

Parallel evolution

A

two species with a common ancestor and remain similar due to similar environment

65
Q

convergent evolution

A

two species with no common ancestor but more and more similar due to environmental pressures.

66
Q

Molecular clock model

A

the more similar two species are, the more recently they split from a common ancestor.

Biology (7 decks)

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