Normal Variation Flashcards
Estimated human mutation rate per generation at any given nucleotide
1.2 x 10^-8 mutations
What factor increases mutation rate?
Older fathers- additional 2.01 mutations/year
Why mothers don’t produce as many mutations as fathers
Female gametes are made early in life and are not constantly dividing, like male gametes
Types of mutations that happen more often than those at single nucleotides
Mitochondrial DNA
Microsatellites (regions in genome with many repeats)
CpG dinucleotides
Fitness
Reproductive success of an individual: number of viable, fertile offspring produced
Effects of mutations in different areas of genes on fitness
Mutations in transcription start sites: bad
Mutations in intergenic regions: neutral
Neutral theory of molecular evolution
Most variants that exist in a population are evolutionarily neutral: their effects on fitness are too small to be acted upon by selection
Genetic drift
In every generation, frequency of evolutionarily neutral variants will randomly drift up and down due to random sampling of gametes
Age of common variants
Common variants are old: it takes time for a new mutation to rise to high frequency
Why are deleterious variants rare in populations?
They are rapidly eliminated by selection
Which spreads faster: adaptive or neutral variants?
Adaptive
Limitations of short read sequencing
Repetitive regions are hard to align
Presence of transpositions (sections of DNA that move)
Complex rearrangements
Do humans have high or low genetic diversity compared to other species?
Low: 1/1000 base differences between two typical genomes
How many variants does a typical human have compared to a reference genome?
3-4 million
How many rare variants does a typical human have that are not found in other genomes?
10,000-15,000
