4.2 Patterns in Heredity Mrs. Leos May 25, 2019

SO FAR…….. We have learned: NOW we will learn: Genes are passed from parents to offspring Offspring inherit genes in predictable patterns NOW we will learn: how punnett squares can be used to predict patterns in heredity How ratios and probability can be used to predict patterns of heredity

Punnett Square illustrates how the parents’ alleles might combine in offspring Dominant & recessive alleles represented by letter Capital letter stands for dominant allele Small letter stand for a recessive allele Shows genetic make- up or genotype of organism

Punnett Square T t Letters of two alleles from one parent are written on top of square Second parent on side of square T t

One allele per parent in square Letters filling squares are genotype T t TT Tt tt T t

Ratio Compares, or shows the relationship between two quantities

Probability Likelihood or chance of a specific outcome in relation to the total number of possible outcomes

Two alleles for a trait are different Tt Heterozygous OR Hybrid Two alleles for a trait are different Tt

Hybrid Offspring may look the same or different Genes are different

Homozygous Organism always produces same trait in offspring tt TT

mutation Any change made to DNA

On page 31 Punnett Square worksheet