Probability and The Punnett Square

Gaiser Life Science

Know

Evidence

Page 37

Probability and The Punnett Square

What are the chances of flipping a coin and landing on tails?Explain your answer.

The Punnett Square

Clarifying ?s Information

Page 38

probability - The chance/likelihood that something will happen- The chance/likelihood that something will happen

- a chart that shows all possible genetic crosses- a chart that shows all possible genetic crosses

Example: flipping a coin – 50/50 chance of landing on heads (50/50, 1 in 2, 1:1, ½, 50%)

Example: Dad’s alleles = Tt, Mom’s alleles = TT

Punnett Square

- Mendel was the first scientist to determine that probability could be used to predict genetic crosses.

used to determine the probability of a specific outcome

T t

T TT Tt

T TT tT

25% 25%

25% 25%

1 in 4 chance of a specific outcomeOffspring has a 100% chance of being tall.

Probability and The Punnett Square

- Reginald C. Punnett originated the Punnett Square.

Clarifying ?s Information

Page 39

Summary:

- an organism’s genetic make-up

- an organism’s physical appearance/visible traits

- two identical alleles

pheno = physical

genotype

phenotype

homozygousExample: TT or tt

Example: Tt

heterozygous - two different alleles

codominance - alleles are neither dominant or recessive – both show up in offspring

Example: being tall

Example: Tt

Example: black chickens & white chickens – the offspring have both black and white feathers

Probability and The Punnett Square

Page 38

Clarifying ?s InformationProbability and The Punnett Square

probability - The chance/likelihood that something will happen- The chance/likelihood that something will happen

- a chart that shows all possible genetic crosses- a chart that shows all possible genetic crosses

Example: flipping a coin – 50/50 chance of landing on heads (50/50, 1 in 2, 1:1, ½, 50%)

Example: Dad’s alleles = Tt, Mom’s alleles = TT

Punnett Square

- Mendel was the first scientist to determine that probability could be used to predict genetic crosses.

used to determine the probability of a specific outcome

1 in 4 chance of a specific outcomeOffspring has a 100% chance of being tall.

- Reginald C. Punnett originated the Punnett Square.

T t

T TT Tt

T TT tT

25% 25%

25% 25%

Page 39

Clarifying ?s Information

Summary:

Probability and The Punnett Square

- an organism’s genetic make-up

- an organism’s physical appearance/visible traits

- two identical alleles

pheno = physical

genotype

phenotype

homozygousExample: TT or tt

Example: Tt

heterozygous - two different alleles

codominance - alleles are neither dominant or recessive – both show up in offspring

Example: being tall

Example: Tt

Example: black chickens & white chickens – the offspring have both black and white feathers

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