Lecture 6 - Population Genetics Part 1

What is a mutation?

change in an organisms dna

How do mutations increase genetic variation?

can create new alleles

What are four types of DNA mutation?

single nucleotide changes, insertions, deletions, structural variants

Why are mutations described as random?

occur without regard to if they benefit the cell

What is the difference between germline and somatic mutations?

germline mutations can be inherited, somatic mutations can not

How can a germline mutation affect a population?

introduces a new allele into the germ pool

Do all mutations change phenotype?

no, many are neutral

What causes sickle-cell disease at the protein level?

valine replaces glutamic acid in beta-globin

How does sickle-cell haemoglobin affect red blood cells?

forms fibres in low oxygen, making cells sickle shaped

Why can sickle-shaped cells cause organ damage?

can block small blood vessels and reduce blood flow

What is the inheritance pattern of sickle-cell disease?

autosomal recessive, caused by two sickle cell alleles

What is sickle-cell trait?

having one normal allele and one sickle cell allele

Why is the sickle-cell allele common in some malaria-affected populations?

one copy can reduce the frequency and severity of malaria attacks

What is a population gene pool?

all alleles of genes in a population

What is Hardy–Weinberg equilibrium?

allele and gene frequencies remain constant across generations

What does (p) represent in Hardy–Weinberg equations?

frequency of dominant allele

What does (q) represent in Hardy–Weinberg equations?

frequency of recessive allele

What is the Hardy–Weinberg allele-frequency equation?

p + q = 1

What is the Hardy–Weinberg genotype-frequency equation?

p squared + 2pq + q squared = 1

What do (p^2\), (2pq) and (q^2) represent?

homozygous first allele, heterozygous, homozygous second allele