7 Genetics & Ecosystems- Populations

Question 1

What is a population?

Answer 1

-all the individuals of a species living within a specific area
-can potentially interbreed

Question 2

What is a species?

Answer 2

a group of individual organisms that interbreed and produce fertile, viable offspring

Question 3

How is one species distinguished from another?

Answer 3

when matings between individuals from each species don’t produce fertile offspring

Question 4

What are multiple populations in an area?

Answer 4

-may live in the same specific area
-can be multiple populations of the same species.

Question 5

What is a gene pool and what individuals share them?

Answer 5

-sum of all alleles in a population; each individual has a different combination of alleles in their chromosomes.
-populations of a species share a gene pool.

Question 6

What is allele frequency and how can it be increased?

Answer 6

-the rate at which a specific allele appears within a population.
-if allele—> particularly advantageous for survival, individual that possesses it will be more likely to reproduce than individual that doesn’t
-means the allele is more likely to be passed onto its offspring.
-over time, this allele will likely increase in frequency

Question 7

What does the Hardy-Weinberg principle predict and why?

Answer 7

-that allele frequencies won’t change from generation to generation
-this is because a population’s allele & genotype frequencies= inherently stable.

Question 8

What assumptions are made for the Hardy-Weinberg to work and why is this useful?

Answer 8

-no mutations, migration or emigration.
-no selective pressure for/against a specific genotype.
-population size= infinite.
-in real populations—> assumptions aren’t normally met but making assumptions= still useful as it provides a model we can compare to real population changes.

Question 9

What is the Hardy-Weinberg equation?

Answer 9

p² + 2pq + q² = 1

Question 10

How is the Hardy-Weinberg equation used?

Answer 10

-for every gene, there are 2 alleles present in an individual (except some genes on the X chromosome).
-if you know the frequency of 1 of these alleles, equation p + q = 1 can be used to calculate frequency of other allele.
-p = frequency of one allele.
-q = frequency of other allele.
p² = pp = homozygous dominant.
q² = qq = homozygous recessive.
2pq = heterozygous.
-components of the equation allows us to calculate # of individuals in a pop that have each genotype

Question 11

How can the Hardy-Weinberg equation be used to predict genotypes?

Answer 11

-by observing phenotypes in a population, you can identify how many individuals carry homozygous recessive allele genotype (q² )
-only homozygous recessive individuals show recessive phenotype.
-Individuals w/ dominant phenotype could= homozygous dominant/heterozygous.
- # can be used in Hardy-Weinberg equation to allow the frequencies other two genotypes to be estimated.