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Flashcards in Population Genetics Deck (18)
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1
Q

Average genetic difference between two random human beings

A

~1/1000 bp

or, about 99.9% the same

2
Q

About what percentage of all variants are SNPs?

A

90%

The remaining 10% are either rarer, or are variants of a different sort – stretches of the DNA where there is either extra or missing DNA sequence

3
Q

Average genetic difference between two random chimps

A

About ~1/300 bp

About 99.6% the same

This represents about 3 times the genetic diversity that humans have

4
Q

Average genetic difference between a random human and a random chimp

A

~1/100 bp

About 99.0% the same

5
Q

De Novo Human Mutation Rate

A

1.2 x 10-8 mutations per base pair per generation

or

1.2 de novo mutations per 108 bp per generation

Note: David Reich’s estimate is slightly larger, obtained using microsatellite data.

6
Q

Mutation rate, gender, and age

A

Most new mutations come from the paternal line (~85% of all new mutations). Furthermore, the mutation rate increases with advancing paternal age. There may also be some variability between people in mutation rates, but this has not yet been thoroughly studied

7
Q

Every human carries approximately ___ unique de novo mutations.

A

100 unique de novo mutations

8
Q

Probability of neutral allele peristence

A

1 / 2N

Where N is a product of population size

The 1/2 is the coinflip regarding whether or not the de novo gene is passed on in reproduction.

N is a complicated function dealing with survival, reproduction rate, population size, etc.

9
Q

Quantitative Human Genetic Drift

A

N = 10,000 because for most of human history, the human population size has been 10,000

10
Q

Genetic drift is greater in . . .

A

a smaller population

11
Q

Typically, deleterious mutations are ___ and ___.

A

Typically, deleterious mutations are rare and young.

12
Q

Each person carries dozens or hundreds of loss of function alleles, but these mostly go unobserved because. . .

A

recessive embryonic lethal

13
Q

Proportion vs Minor Allele Frequency for deleterious vs neutral mutations

A
14
Q

Impacts of rapid expansion on the human genome

A

The impact of the expansion has been to increase the number of rare alleles compared with what would be expected under a constant sized population.

15
Q

Linkage disequilibrium

A

How shared ancestry and recombination leads to different degrees of correlation amonge alleles.

16
Q

Haplotype

A

Combination of variants along a chromosome.

17
Q

Recombination “hotspots”

A

As it turns out, recombination is mostly limited to certain “hotspots” in the genome and is not as random as once presumed.

These are marked by a particular motif that is recognized by the zinc-finger protein PRDM9.

David Reich has shown that certain African populations have a different form of PRDM9 that accounts for their ability to recombine at different areas in the genome.

18
Q

Hardy-Weinberg Equilibrium

A