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

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Transcript of IB Biology Option D D4 The Hardy Weinberg Principle Jason de Nys IB Biology Option D D4 The Hardy...

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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 IBO 2007 All images CC or public domain or link to original material. http://commons.wikimedia.org/wiki/File:Laurelyhardy_179.jpg http://www.flickr.com/photos/shoot-art/3921390861/ http://www.flickr.com/photos/rietje/76575482/sizes/m/in/photostream/ Slide 2 The HardyWeinberg principle states that both allele and genotype frequencies in a population remain constant that is, they are in equilibriumfrom 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/ Slide 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: http://en.wikipedia.org/wiki/Hardy%E2%80%93Weinberg_principle Slide 4 http://commons.wikimedia.org/wiki/File:Hardy-Weinberg.svg Slide 5 An interactive that charts the changes in frequency and represents them as areas: Slide 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 Slide 7 Slide 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 constantthat is, they are in equilibriumfrom generation to generation What must be the underlying assumptions? Slide 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 Slide 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 Slide 11 Online Quiz Further information: Good video Also revises directional selection: Salman Khan explains HWE