Start-up for Tuesday, November 6, 2012 For each genotype, indicate whether it is heterozygous or homozygous: For each genotype, determine the phenotype: Purple flowers are dominant to white flowers: For each phenotype, list a different genotype (use the letter of the dominant trait) Tall plants are dominant to short plants Ee B) GG C) HH D) Jj E) pp PP B) Pp C) pp Tall C) Short

Mendelelian Genetics Chapter 11 Section 2 Objective: Summarize Mendel’s Law of Segregation Define monohybrid and dihybrid crosses List the purpose and steps of completing a Punnett Square Use punnett squares to predict genotypic and phenotypic expectations of single trait crosses

Obj. A) Summarize Mendels’ Law of Segregation – Focus on the F2 During the formation of gametes (eggs or sperm), the two alleles for a trait separate from each other. Each gamete carries a single copy of each gene Alleles for a trait are then "recombined" at fertilization, one from each parent producing the genotype for the traits of the offspring

Cross 2 Pure Plants TT x tt Results in all Hybrids Tt A) Summarize Mendel’s Law of Segregation Cross 2 Pure Plants TT x tt Results in all Hybrids Tt Cross 2 Hybrids get 3 Tall & 1 Short TT, Tt, tt Because short reappeared in F2, he knew the allele for shortness had not disappeared, the F1 still carried it. F1 cross proves segregation.

Obj B) Define monohybrid and dihybrid crosses Heredity - passing of traits Genetics - study of heredity Monohybrid cross - cross of a single hybrid trait, proves segregation law e.g. flower color Dihybrid cross - cross of two hybrid traits, proves independent assortment e.g. flower color & plant height

Obj C)List the purpose and steps of completing a Punnett Square Used to predict genetic cross outcomes Gives a mathematical percentage for the offspring of a genetic cross = probability (expectation)

C) List the purpose and steps of completing a Punnett Square ID the parent genotypes. Use letter of dominant trait. Make the grid. Place alleles of one parent along the top. Place alleles of other parent on the left side. This will split them. http://www.mhhe.com/biosci/genbio/virtual_labs/BL_05/BL_05.html

4. Fill in the grid like multiplication tables. C) List the purpose and steps of completing a Punnett Square 4. Fill in the grid like multiplication tables. Write the genotypes. Use the Law of Dominance to determine phenotypes. Any capital letter = dominant trait appearance. What is the only way to receive a recessive trait? http://www.mhhe.com/biosci/genbio/virtual_labs/BL_05/BL_05.html

r r Rr Rr R R Rr Rr P1 Single Trait Cross Trait: Seed Shape Obj. D) Use punnett squares to predict genotypic and phenotypic expectations of single trait crosses P1 Single Trait Cross Trait: Seed Shape Alleles: R – Round r – Wrinkled Cross: Homozygous Round seeds x Wrinkled seeds RR x rr r r Genotype Ratio: 100% Rr Phenotype Ratio: 100% Round Rr Rr R R Rr Rr

R r RR Rr R r Rr rr F1 Monohybrid Cross Trait: Seed Shape Obj. D) Use punnett squares to predict genotypic and phenotypic expectations of single trait crosses F1 Monohybrid Cross Trait: Seed Shape Alleles: R – Round r – Wrinkled Cross: Heterozygous seeds x Heterozygous seeds Rr x Rr Genotype: 25% RR, 50% Rr, 25% rr Phenotype: 75% Round & 25% wrinkled G.Ratio: 1:2:1 P.Ratio: 3:1 R r RR Rr R r Rr rr

P p Pp pp p p Pp pp Single Trait Practice Trait: Flower color Obj. D) Use punnett squares to predict genotypic and phenotypic expectations of single trait crosses Single Trait Practice Trait: Flower color Alleles: P – Purple p – White Cross: White flowers x Heterozygous flowers pp x Pp Genotype: 50% Pp, 50% pp Phenotype: 50% Purple, 50% White Genotypic Ratio: 1:1 Phenotypic Ratio: 1:1 P p Pp pp p p Pp pp

Summary of Single Trait Crosses Inheritable factors or genes are responsible for all heritable characteristics Phenotype is based on Genotype Each trait is based on two alleles, one from the mother and the other from the father True-breeding individuals are homozygous (both alleles) are the same

Single Trait Practice Understanding Check Trait: Flower Height Alleles: T – Tall t – short Cross: Homozygous tall x Heterozygous plant x Genotype Percentages: Phenotype Percentages: