Probability and Punnett Squares

By Scott Birns

Definition-The likelihood that a particular event will occur.

Does Tail’s really never fail?◦ Past outcomes do not affect future ones.

Principles of probability can be used to predict the outcomes of genetic crosses.◦ The way in which alleles segregate is

completely random, like a coin flip.

Probability

Today all of you are scientists who are stationed at Bikini Bottom. For the past couple of weeks you have been investigating the genetic makeup of the organisms in this community. Use the information provided and your textbook to answer each question.

Bikini Bottom Genetics

Homozygous (pure breed)- Having two identical alleles for a given gene.

Heterozygous (hybrid)- Having two different alleles for a given gene.

Phenotype- The observable physical traits of an organism, which are determined by its genotype.

Genotype- The genetic makeup of an organism. Punnett square-A diagram used in the study of inheritance to

show the combinations that might result from a genetic-cross.

Review