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# Probability and Punnett Squares - PowerPoint PPT Presentation

Probability and Punnett Squares. Probability. Probability a number that describes how likely it is something will happen Can be expressed as a ratio, fraction, or percentage When you flip a coin, you have what probability of getting heads? 1 out of 2 1 : 2 (ratio) ½ (fraction)

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## PowerPoint Slideshow about 'Probability and Punnett Squares' - mandy

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### Probability and Punnett Squares

• Probability a number that describes how likely it is something will happen

• Can be expressed as a ratio, fraction, or percentage

• When you flip a coin, you have what probability of getting heads?

• 1 out of 2

• 1 : 2 (ratio)

• ½ (fraction)

• 50% (percentage)

Punnett Squares

• Chart that shows all the possible outcomes of a genetic cross – allows you to determine the probability

Determining genotype and phenotype ratios from a punnett square

• Genotype Ratios

• 1 GG : 2 Gg : 1 gg

• 25% GG, 50% Gg, 25% gg

• Phenotype Ratios

• 3 Green : 1 white

• 75% Green, 25% white

• In chickens, brown feathers are dominant to blue.

• Cross a heterozygous brown chicken with a blue chicken. Give genotype and phenotype ratios

Genotypes : 50 % Bb , 50 % bb

Phenotypes: 50% Brown, 50 % blue