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IB Biology Option D D4 The Hardy Weinberg Principle Jason de Nys IB Biology Option D D4 The Hardy Weinberg Principle Jason de Nys All syllabus statements.

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Presentation on theme: "IB Biology Option D D4 The Hardy Weinberg Principle Jason de Nys IB Biology Option D D4 The Hardy Weinberg Principle Jason de Nys All syllabus statements."— Presentation transcript:

1 IB Biology Option D D4 The Hardy Weinberg Principle Jason de Nys IB Biology Option D D4 The Hardy Weinberg Principle Jason de Nys All syllabus statements ©IBO 2007 All images CC or public domain or link to original material.

2 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

3 Consider two alleles A and a A has a frequency of p a 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:

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5 An interactive that charts the changes in frequency and represents them as areas:

6 D4.2 Calculate allele, genotype and phenotype frequencies for two allelles of a gene, using the Hardy-Weinberg equation Online practise questions Online practise questions And more practise And more practise

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8 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?

9 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

10 For the equation to work mathematically: -The organism involved must be diploid and reproduce sexually -Generations must not overlap -The trait must be autosomal

11 Online Quiz Further information: Good video Also revises directional selection: Salman Khan explains HWE


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