00:01
In a human population, we have the genotype frequencies at a particular locust.
00:07
So this is 0 .7, this is 0 .2.
00:13
This is 0 .1.
00:15
This makes sense, because these are the only three possible genotypes if there are two allules.
00:20
So their frequencies are going to have to add up to 1, which is 100%.
00:24
We want the frequency of the dominant allele.
00:28
How do we work this out? in a way, we know the genotype of everybody in the population.
00:33
So if i imagine, instead of frequencies, i have number of people.
00:40
Let's say we take 100 people and we would say, okay, 70 of them would be homozygous dominance, 20 of them would be heterozygous, 10 of them would be homozygous recessive.
00:51
So i'm going to imagine 100 people.
01:01
Those 100 people get two copies of a gene each.
01:05
So in those 100 people, you have 200 copies.
01:10
Of the gene.
01:14
And this is the real population we're working with here, the gene copies.
01:18
Because what i'm going to do to work out this frequency, i'm actually going to add up how many of the copies would be dominant.
01:25
And we can do that...