Hardy- Weinberg Principle

This is what happens when biology gets too influenced by maths.

No biology, you don't understand. There are students who picked you over maths cause they can't deal with x's and y's in their lives. THEY PICKED YOU! They decided to go through all the hardships of remembering fancy latin names no one understands and be loyal to YOU! and what do you do in return? Bring algebra even into Biology.

Disappointing

Anyway, let's start with the blog. (Yes, this writers done ranting for now (ง •_•)ง )

This principle governs a major part of the studies which helps us understand evolution and concept of natural selection. This blog takes you through it in a nutshell!

Let's start with the basic definitions:-

Allele , in simple words ,can be put as the parts help in exhibiting genetic traits (Brown eyes, black hair etc). They appear in chromosomes ( another part of the genetic system) in pairs.

So Allele frequency is the relative number of times a particular trait occurs- Number of people with brown eyes in a generation.

The Hardy-Weinberg Principle:-

It says that allele frequencies in a population are stable and constant from one generation to another. This is called genetic equilbrium. Sum total of all allelic frequencies is 1.

Let the probability of a particular allele 'A' to appear is 'p'

Similarly probabilty of allele 'a' is 'q'

If we consider only these two conditions then there is a possibilty of three cases

1. Both chromosomes have AA

2. Both chromosomes have aa

3. Each choromosome has one type i.e Aa type

From maths probability we know how to calculate the probability of these events occuring,

(Not able to connect? Lets take an example of tossing a coin

Probability that we get heads is 1/2 and tails 1/2.

Proability of me tossing the coin twice and getting heads both times is 1/2 * 1/2 = 1/4)

Probability of getting AA type = p^2 (p squared)

Proability of getting aa type = q^2 ( q squared)

Probability of getting Aa type (or aA) = 2pq

When added

p^2 + q^2 + 2pq = 1 which is binomial expansion of (p+q)^2 !!

This concept helps us understand the changes in the gene frequencies and direction of evolution.