bio paper 2

Explain the evidence from a pedigree diagram which would show that an allele is dominant

Parents with phenotype have a child without phenotype. So both parents must be heterozygous. If it were receive, all offspring would have it

Explain the evidence from a pedigree diagram showing an allele is recessive

Parents without phenotype have a child with phenotype. So both parents must be heterozygous for allele

Evidence with a pedigree diagram that the allele for a phenotype in the X chromosome is recessive

Mother without phenotype has child with phenotype. So mother must be heterozygous

Evidence from pedigree diagram for a recessive phenotype being caused by a gene on the X chromosome

Only males tend to have the recessive phenotype

Evidence from pedigree diagram that gene for phenotype isn’t on X chromosome

Father with phenotype has daughter without phenotype. Father would’ve passed on the allele for the phenotype on his X chromosome so daughter would have phenotype

OR

mom with phenotype has a son without phenotype. Mother would’ve passed on allele for phenotype on X chromosome so son would’ve have the phenotype

What’s the linkage when the two phenotypes of the two parents (e.g. GgLl and ggll) are the same as their offspring

Autosomal linkage (2 genes located on the same non sex chromosome). so alleles on same chromosome are inherited together and stay together during independent segregation.

No crossing over. since they’re close together on an autosome, they’re less likely to be separated by crossing over.

So no new combinations of gametes produced (e.g. Gl or gL)

What’s hardy- Weinberg

A maths model used to predict the allele frequencies (the proportion of an allele within a gene pool (all the alleles of the genes within a population at one time)) within a population (all the individuals of one species in one area at one time)

Hardy- Weinberg assumptions

Allele frequencies won’t change from generation to generation given:

Population is large

no immigration/ emigration (to introduce/ remove alleles)

No mutations (to create new alleles)

No selection for/ against alleles

Mating is random

Hardy Weinberg equations

p² + 2pq + p² = 1

p + q = 1