Mutation and Selection Flashcards
What are the two types of point mutations?
Random copying errors - in synthesis of DNA
Random repair errors - following DNA damage
What are transitions and transversions? Which is less common?
Transitions change from purine to purine or pyrimidine to pyrimidine
Transversions change from purine to pyrimidine or vice versa - less common
What causes gene duplication and deletion?
Unequal crossing over in meiosis in repetitive regions of DNA
Define polyploidy and aneuploidy
Polyploidy - doubling of all chromosomes
Aneuploidy - fission, fusion or doubling of only some chromosomes
What are the equations for mutation frequency for A and a without back mutation?
p’ = p(1-u)
q’ = q + pu
What is the stable equilibrium equation for mutations with back mutation?
p* = v/(u + v)
Define selection and fitness
Selection - difference in survival between individuals with different genotypes or phenotypes
Fitness - The extent to which an individual contributes genes to the next generation
What was the food spiked with in the ADH fruitfly test?
Ethanol
What is the trend of alleles with a recessive lethal allele?
Recessive alleles are slowly eliminated when they are rare
Favoured allele increases in frequency
What is the equation for balancing selection?
p* = s/(s + t)
What are the harms and benefits of Sickle Cell?
Sickle cells block capillaries and cause death in many patients.
Heterozygotes sickle when O2 concentration drops, like in malarial attack, and destroy the parasite
Relate the prevalence of sickle cell anaemia and malaria to selection
Because being heterozygous for sickle cell is partially beneficial, the areas of higher malaria has higher levels of sickle cell and vice versa
How is spinal muscular atrophy maintained?
Through mutation-selection balance. The observed mutation rate matches the expected mutation rate
What is one way of accounting for frequency of a disease?
The ratio of new mutations per patient
