# How can the hardy-weinberg equation be calculated?

##### 3 Answers

To calculate Hardy-Weinberg equation you need to have the proportion of the studied genotype in order to calculate their frequence in the population from which you will find theorical frequency and then check if it matches reality.

#### Explanation:

To start let's recall the Wardy Weinberg equation :

with p the frequency of an allele A1 and q the frequence of an allele A2.

Let's try an example. In a population there are two alleles M and N with three possible genotypes:

homozygote MM : 1787 individuals

homozygot NN : 1303 individuals

heterozygot NM : 3039 individuals

Total population : 6129

We can calculate the frequency of each genotype :

F11 = frequency of MM

F22= frequency of NN

F12= frequency of NM

We then calculate the frequency p of M and q of N in the population:

Now that we have the Hardy Weinberg frequency, we can calculate the theorical frequency of the genotype by multiplying the frequency by the total population:

MM

theoretical frequency of MM

NN

theoretical frequency of NN

NM

theoretical frequency of NM

Now that we have those theoretical frequencies, we can compare them to the real frequencies and check if the population is or isn't at the Hardy Weinberg equilibrium with, for instance, a

#### Explanation:

When calculating for a ratio in a species that is in HW equilibrium, the two important equations are

The

The

If you know the value for either p or q and need to know the other, you can use the equation

Let's look at a quick example:

In a rat population that is in Hardy-Weinberg equilibrium, 60% of the population is homozygous dominant for the trait of brown fur. Calculate the percentage of the population that is heterozygous for the trait of brown fur.

P2 +2pq+q2=1

#### Explanation:

The two alleles p and q represent the frquencies of all alleles. Therefore, p+q=1 or p=1-q. If the equation P2 +2pq+q2=1, p is substituted by 1-q or q is substituted by 1-p. Thanks.