Probability and HeredityProbability and Heredity

Probability Probability  describes how likely it is that an event will happen

Phenotype  physical appearance of an organism Genotype  genetic combination or allele combinations

Homozygous  an organism that has two identical alleles for a trait Heterozygous  an organism that has two different alleles for a trait

Punnett Squares Punnett Square  a chart that shows all the possible combinations of alleles that can result from a genetic cross Make a tic-tac-toe board. X out the top left corner. Write the male’s alleles across the top. Write the female’s alleles down the side. Match the column & rows for each box. Write the capital letter first.

A Punnett Square

- Probability and Heredity Probability and Genetics In a genetic cross, the allele that each parent will pass on to its offspring is based on probability.

Practice with terms. For all questions, use these facts: the trait is fur color (f). Black fur is dominant over gray fur. Write the letter of the dominant allele. _________ Write the letter of the recessive allele. _________

Write the genotype for gray fur (2 alleles!). _________ Write the genotype for Black fur (2alleles!). _________ or _________

Write out the homozygous recessive genotype. _________ Write out the homozygous dominant genotype. _________ Write out the heterozygous genotype. _________

Write the phenotype for #5. _________ Write the phenotype for #6. _________ Write the phenotype for #7. _________

If the mother is homozygous recessive and the father is homozygous dominant…….. a) Write the genotype probabilities. b) Write the phenotype probabilities.