Dihybrid Inheritance Mendels Peas Unit 18 Genetics Assignment

Dihybrid Inheritance Mendel’s Peas Unit 18: Genetics Assignment 3: Inheritance

Starter Activity 1 Define the following terms: 1) Allele 2) Heterozygous 3) Homozygous

Starter Activity 2 Which of these genotypes are a) Heterozygous b) Homozygous Bb LL Ww ff Gg Tt WW

Starter Activity 3 a) Construct a Punnett square for the following genetic cross: Parent 1: Red Petals Parent 2: Pink Petals Rr X rr b) What proportion of the offspring will have (i) Red petals? (ii) Pink Petals

Follow up question: • If the plant produced 50 offspring, how many would you expect to have (i) Red petals (ii) Pink petals. In nature, do you think this would be the case? What if it produced 10000 offspring, would the outcomes be closer to the expected? Why?

Dihybrid Inheritance The inheritance of two related traits. e. g. The height of a plant and its petal colours T = Tall t = short R = Red r = pink We can write genomes like this: Tt. Rr or TTRR

Punnett Square F 1 Generation: Parent 1) TTRR TR tr tr Parent 2) ttrr TR TR TR

Punnett Square F 1 Generation: Parent 1) TTRR Parent 2) ttrr TR TR tr Tt. Tr Tt. Tr

100 % Offspring have the Genotype: Tt. Rr What is their Phenotype? Tall, Red Construct a Punnett square for the F 2 Generation:

Parent 1) Tt. Rr Parent 2) Tt. Rr TR TR Tr t. R tr

Parent 1) Tt. Rr Parent 2) Tt. Rr TR Tr t. R tr TR TTRr Tt. RR Tt. Rr Tr TTRr TTrr Tt. Rr Ttrr t. R Tt. Rr tt. RR tt. Rr tr Tt. Rr Ttrr tt. Rr ttrr

9: 3: 3: 1 ratio Red, Tall = 9 Red, Short = 3 Pink, Tall = 3 Pink, Short = 1

Who Was Gregor Mendel? • Pea experiments • Inheritance

Class Work Complete the worksheet applying the principles we have covered with tall/short, red/pink flowers to the example of Mendel’s pea plants.

Video: https: //www. youtube. com/watch? v=Y 1 PCwx. UD Tl 8

Plenary Activity: Cats! B = Grey b = ginger S = Dark stripes s = no stripes Write out all possible genotypes / phenotypes:

Answers: You could have: Bb. Ss, BBSS = Grey, Stripes BBss, Bbss = Grey, no Stripes bb. Ss, bb. SS = ginger, stripes bbss = ginger no stripes