exam revision - changes in genetic makeup

Question 1

how can allele frequencies be altered

Answer 1

mutation, gene flow, small population size, genetic drift, natural selection, non-random mating.

Question 2

what are mutations

Answer 2

spontaneous mutations can alter allele frequencies and create new alleles.

Question 3

what are the types of mutations

Answer 3

block mutations, chromosome mutations, point mutations,

Question 4

what are block mutations

Answer 4

are mutations when a small portion of a chromosome is changed. Can be deletion (removed), inversion (pieces of chromosome are flipped so genes appear in reverse), translocation (pieces of chromosome are moved from one chromosome to another), duplication (pieces of chromosome are repeated)

Question 5

what are point mutations

Answer 5

are mutations that affect single nucleotides, change the sequence of bases in DNA.

Question 6

what are chromosome mutations

Answer 6

are mutations that affect whole chromosomes, they occur due to whole chromosomes being “misplaced”, can be aneuploidy (single chromosome added), or can be polyploidy (extra chromosome to every set)

Question 7

what is gene flow

Answer 7

genes can be exchanged with other gene pools as individuals move between them

Question 8

how does small population size affect allele frequencies

Answer 8

in small populations allele frequencies can change randomly from generation to generation; alleles may be lost or fixed

Question 9

what is natural selection (rules)

Answer 9

1. there must be genetic variation within a population. 2. Some kind of selective pressure is applied to the population due to change in environment. 3. over time those with favoured phenotypes will have a higher chance of survival and reproduction. 4. over time there is a greater chance of offspring having favoured phenotypes. 5. the favoured phenotype will increase if selective pressures dont change. over time a new species may evolve

Question 10

what is non random mating

Answer 10

individuals seek out particular phenotypes with which to mate.

Question 11

what is genetic drift

Answer 11

is a mechanism of evolution in which allele frequencies within a population change over generations due to chance. Two types, bottleneck effect, founder effect.

Question 12

what is the bottleneck effect

Answer 12

is when a populations size becomes very small very quickly. Usually this occurs due to a catastrophic event, hunting a species to near extinction, or habitat destruction. When this occurs, many alleles are lost and the genetic variation of the population decreases

Question 13

what is the founder effect

Answer 13

occurs when a group of individuals from one population colonise in a new location and separate from the old one. This greatly reduces population size as well as reduces the genetic variability of the population

Question 14

what are types of variation

Answer 14

sexual reproduction, mutations, gene flow, environmental factors

Question 15

what is speciation and types

Answer 15

speciation is the process of one species becoming seperate species due to some kind of reproductive isolation. The isolation of genes can occur by allopatric speciation as well as sympatric speciation

Question 16

what is allopatric speciation

Answer 16

is the separation of a species by a geographic barrier, eg a river, mountains, canyons, oceans.

Question 17

what is sympatric speciation

Answer 17

is the separation of a species caused by behaviour, chromosome differences, and seasonal behaviour.

Question 18

what is selective breeding

Answer 18

it occurs only when humans intervene, it is the process where we choose characteristics we want in an animal, then breed two animals with these characteristics in order to produce offspring with these characteristics. This is repeated over many generations with offspring who show the most desired characteristics.