Post on 14-Dec-2015
transcript
IB BiologyOption D
D4 The Hardy Weinberg Principle
Jason de Nys
All syllabus statements ©IBO 2007All images CC or public domain or link to original material.
http://commons.wikimedia.org/wiki/File:Laurelyhardy_179.jpghttp://www.flickr.com/photos/shoot-art/3921390861/http://www.flickr.com/photos/rietje/76575482/sizes/m/in/photostream/
The Hardy–Weinberg principle states that both allele and genotype frequencies in a population remain constant
—that is, they are in equilibrium—from generation to generation unless specific disturbing influences are introduced. Wikipedia
D4.1 Explain how the Hardy-Weinberg equation is derived
http://www.flickr.com/photos/west-park/2610430399/
Consider two alleles A and a
A has a frequency of pa has a frequency of q Therefore p + q = 1
As the two alleles are the only options at that locus
Lets make a Punnet square:
http://en.wikipedia.org/wiki/Hardy%E2%80%93Weinberg_principle
http://commons.wikimedia.org/wiki/File:Hardy-Weinberg.svg
An interactive that charts the changes in frequency and represents them as areas:
D4.2 Calculate allele, genotype and phenotype frequencies for two allelles of a gene, using the Hardy-Weinberg equation
Online practise
questions
And more practise
D4.3 State the assumptions made when the Hardy Weinberg equations is used
Okay, so if:
“both allele and genotype frequencies in a population remain constant—that is, they are in equilibrium—from generation to generation”
What must be the underlying assumptions?
Basic Assumptions of the Hardy-Weinberg Principle- All phenotypes equal fitness, no natural selection- No mutation- No immigration or emigration- No genetic drift (infinitely large population)- No assortative mating Of course, at least one of
these factors will be acting on a population in the wild
For the equation to work mathematically:- The organism involved must be diploid
and reproduce sexually- Generations must not overlap- The trait must be autosomal
Online QuizFurther information:
Good video Also revises directional selection:
Salman Khan explains HWE