theme 4b

Question 1

what is evolution?

Answer 1

the change in allele frequencies from one generation to the next

Question 2

is the frequency of an allele in a population always the same as the ratio in a single monohybrid cross?

Answer 2

no. it is often not.

Question 3

what 4 things cause evolution?

Answer 3

natural selection
mutation
migration (gene flow)
genetic drift

Question 4

what is quantitative variation?

Answer 4

variation in continuous traits

Question 5

what is qualitative variation?

Answer 5

variation in discrete traits

Question 6

what is population genetics?

Answer 6

a subdiscipline of genetics that focuses on the genetic variation that exists within a population

Question 7

what is polymorphism?

Answer 7

a difference in the DNA sequence of a given gene in different individuals of a species (different alleles)

Question 8

what is the difference between a genotype and genome?

Answer 8

genotype can refer to only specific genes that are being studied, whereas genome refers to the individual’s entire DNA sequence

Question 9

what letters are used to represent alleles of genes when there are only two different alleles?

Answer 9

p and q, where p represents the dominant allele, and q represents the recessive, if there is dominance

Question 10

what is the null hypothesis for evolution?

Answer 10

there is no change in allele frequencies over time (no evolution)

Question 11

according to the Hardy-Weinberg principle, what conditions are necessary for genetic equilibrium (lack of evolution)?

Answer 11

there are no mutations occuring

the population is closed to migration (no gene flow and therefore no new alleles added)

the population is infinitely big (no genetic drift)

natural selection does not select for or against any of the alleles (all individuals have same fitness, regardless of genotype)

mating is random

Question 12

what is the relationship between population size and genetic drift?

Answer 12

genetic drift can occur, causing changes in allele frequencies and therefore evolution, due to chance alone if the number of matings in a population is extremely low (caused by small population)

Question 13

what is haplotype?

Answer 13

the genotype of a haploid cell

Question 14

what is Hardy-Weinberg equilibrium (HWE)?

Answer 14

genetic equilibrium when all of the Hardy-Weinberg principle conditions are met

Question 15

what is the predicted genotype distribution for HWE?

Answer 15

AA: p^2
Aa: 2pq
aa: q^2

Question 16

can a population that was evolving reach HWE?

Answer 16

yes. one round of random mating, with all the HWE conditions met, will bring the population to equilibrium with genotype frequencies aligning with the HWE predictions

Question 17

what is HWE used for?

Answer 17

to determine if a population is evolving or not

Question 18

how do we check is a population is in HWE?

Answer 18

determine number of individuals with each genotype. use this to find number of each allele in the gene pool.

use allele frequencies to determine HWE predicted genotype frequencies

use frequencies and multiply by total population to determine predicted number of individuals with each genotype

compare observed to expected through the Chi-square test

Question 19

what is the equation for HWE?

Answer 19

p^2 + pq + q^2 = 1