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biology > changes in the genetic makeup of a population > Flashcards

changes in the genetic makeup of a population Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

define gene

A

a segment of DNA coding for a particular characteristic or trait

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2
Q

define allele

A

alternative form of a gene

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3
Q

genotype

A

the alleles possessed by an organism

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4
Q

phenotype

A

the observable characteristics of an organism as a result of the interaction of its genotype with its environment

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5
Q

monogenic trait

A

a trait controlled by one gene

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6
Q

discontinuous variation

A

when there is a limited number of variations determined by a gene

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7
Q

locus

A

a specific position on a chromosome where a particular gene is located

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8
Q

polygenic trait

A

a trait controlled by multiple interacting genes

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9
Q

continuous variation

A

when a gene/s codes for a range of non-distinct variations

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10
Q

gene pool

A

the total sum of alleles found in a population

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11
Q

aneuploidy

A

the presence of an abnormal number of a particular chromosome, either trisomy or monosomy

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12
Q

polyploidy

A

a condition where an organisms has more than 2 complete sets of chromosomes

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13
Q

polymorphism

A

the presence of variations of a gene

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14
Q

define natural selection

A

the influence of environmental pressures on particular phenotypes, impacting allele frequencies within a population

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15
Q

define selection pressures

A

conditions that give organisms with certain traits a reproductive advantage over those with different traits, influencing allele frequency in a population as a result.

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16
Q

genetic drift

A

describes changes in allele frequencies in a populations as a result of random, unselective events - decreases genetic variation

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17
Q

what is the bottleneck effect

A

when a random event, such as a natural disaster, acts on a population, reducing population size and genetic variation. Offspring of surviving individuals can only inherit the remaining alleles, resulting in reduced variation .

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18
Q

are larger or smaller populations more effected by genetic drift

A

smaller

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19
Q

what is founder effect

A

the loss of genetic variation that occurs when a new population is established by a small ‘founder’ group from a larger one.

20
Q

gene flow

A

is the movement of alleles between populations as a result of migration and interbreeding

21
Q

what genetic isolation results in allopatric speciation

A

geographical isolation

22
Q

steps in allopatric speciation

A
  1. geographical isolation, preventing gene flow between the populations
  2. differing selection pressures act on the populations, resulting in differing allele frequencies within the populations
  3. when the populations are brought back together they will be unable to produce viable offspring.
23
Q

alelle frequency

A

the proportion of a particular allele within a population

24
Q

equation for allele frequency

A

2(number of homozygotes) + (number of heterozygotes)
_____________________________________________
2 (total number of individuals)

25
Q

what defines different species

A

when they are unable to produce viable and fertile offspring

26
Q

what is a mutation

A

a change DNA that can affect a single gene, multiple genes, or entire chromosomes

27
Q

what type of mutation can be passed on

A

a germ-line mutation

28
Q

name of a factor that induces mutation

A

a mutagen

29
Q

2 types of point mutation

A

substitution and frameshift

30
Q

types of substitution mutations

A

silent, missense (when substitution results in an amino acid replacement) and nonsense (when substitution results in a stop codon)

31
Q

which has more of an effect, substitution or frameshift

A

frameshift as it alters every following codon.

32
Q

types of block mutations

A

duplications (part of a chromosome is replicated), deletion mutation (part of a chromosome is removed), inversion mutations (section of DNA breaks off, rotates 180 degrees and reattaches), insertion mutations (when a section of one chromosome breaks off and reattaches to another), translocations (when segments of chromosomes are exchanged with each other)

33
Q

define evolution

A

the change in genetic composition of populations over time

34
Q

speciation

A

the process by which populations evolve to become distinct species

35
Q

prezygotic isolating mechanisms

A

geographical, temporal, ecological (niche partitioning), behavioural, morphological

36
Q

postzygotic isolating mechanisms

A

hybrid inviability (zygote dies), reduced hybrid viability (zygote survives but wont reach adulthood), hybrid sterility (cant produce offspring), and hybrid breakdown (sometimes produces offspring but they will be infertile)

37
Q

what is geographical isolation

A

populations occupy and mate in different geographical areas (separated by a geographical barrier)

38
Q

what is temporal isolation

A

populations mate at different times during the year

39
Q

what is ecological isolation (niche partitioning)

A

populations occupy and mate in different ecological niches

40
Q

what is behavioural isolations

A

populations have different courtship rituals

41
Q

what is morphological isolation

A

when the morphological structure of organisms prevent interbreeding

42
Q

what type of isolation in allopatric speciation

A

geographical

43
Q

selective breeding

A

the process by which humans decide which individuals may breed based on ‘favourable’ traits

44
Q

process of selective breeding:

A

a desirable trait is determined, parents who show trait are interbred, offspring that display trait are selected and interbed, process is continued until the population reliably reproduces the trait

45
Q

detrimental effects of selective breeding

A

reduces resistance to environmental changes (reduced genetic variation)
reduces biodiversity
can increase abnormalities due to gene linkage

biology (15 decks)

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