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Genetics Press spacebar to continue...
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Genetics Here is the Gene family. Mr and Mrs Gene are in the centre.
And here are their three children.
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Genes Only one characteristic will be expressed, or seen, in the individual. This gene is said to be dominant. The characteristic that is not seen is said to be recessive. Complete 4
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A Fishy Tale One day, Esther came home from a concert and noticed 8 new baby fish. She also observed that 2 of them were black and 6 were red. “How could this happen?” Esther puzzled. “Both parents were red”.
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Mum to the Rescue Esther's Mum explained a bit more about how genes worked. She suggested that each young fish had two similar genes controlling their colour. One passed down from the mother and one from the father. Mother’s genes Father’s genes Young’s genes
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Mum to the Rescue Possibility 1 Genotype RR Phenotype Red scales r R R
Mother’s alleles Father’s alleles R r Young’s alleles R R Genotype RR Phenotype Red scales
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Mum to the Rescue Possibility 2 Genotype Rr Phenotype Red scales r R R
Mother’s alleles Father’s alleles R r Young’s alleles R r Genotype Rr Phenotype Red scales
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Mum to the Rescue Possibility 3 Genotype Rr Phenotype Red scales r R r
Mother’s alleles Father’s alleles R r Young’s alleles r R Genotype Rr Phenotype Red scales
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Mum to the Rescue Possibility 4 Genotype rr Phenotype Black scales r R
Mother’s alleles Father’s alleles R r Young’s alleles r r Genotype rr Phenotype Black scales
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Mum to the Rescue rr Rr r RR R
We can show all these possibilities in a diagram called a Punnet square … Possibility 1 rr Rr r RR R Parent 2 Parent 1 Possibility 3 Possibility 2 Possibility 4
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Hooked Noses 1 2 8 7 6 5 4 3 9 10 11 12 If H = hooked nose and h = normal nose, what is the genotype of individual 9? What is the genotype of individual 5? Female Hooked Nose Male No Hooked Nose Complete ‘Hooked Noses’
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Punnet Squares Parent 1 B
Bb Parent 1 B b Parent 2 This punnet square was to be used to predict the eye colour of a child of Parents 1 and 2. Unfortunately, it has been damaged. The gene for brown eyes, B, is dominant over the gene for blue eyes, b.
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Human Blood Types There are four main blood types in humans: A, B, AB and O. There are 3 genes which carry blood type: A, B and O. A person carries 2 of the 3 genes.
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Cloning in Nature 1. How is this type of breeding similar to cloning? How is it different to cloning? 2. “Armadillos are taking a risk in producing identical offspring”. Why might the armadillos be at risk from this type of reproduction? Worksheet
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ORB Education Visit http://www.orbeducation.com for
PowerPoint presentation by Jo Kennedy Graphics & Design by Esther Kennedy Thanks to the students for the use of their photos ORB Education Visit for a range of quality teaching materials.
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