Question

3) Using the gene symbols from the table below, give the genotype(s) for the following phenotypes: white flower, round seeds, and yellow seeds.

Table 1. Characters and traits for Mendel’s pea plants.

Character	Dominant Trait	Gene Symbol	Recessive Trait	Gene Symbol
Flower color	Purple	P	White	p
Seed color	Yellow	Y	Green	y
Seed shape	Round	R	Wrinkled	r

Monohybrid cross

4) You are attempting to re-create some of Mendel’s experiments. You love your plants so much that you give them names. In your garden, one plant, Jenny, is pollenated by another plant, Johnny (peas have perfect flowers, so even though we are assigning them a single sex, they technically are both male and female). Jenny is homozygous dominant for purple flowers and Johnny has white flowers. In order to figure out what kind genotypes and in what ratios their offspring will be, you will construct a Punnett square. To do this, list ALL possible gamete types for Johnny and Jenny. Remember that gametes are haploid and therefore only have one copy of each allele!

5) Place the gametes you generated in 4) in the top row for Johnny and left column for Jenny of the Punnett square below. Then copy and paste the Punnett square below into your lab write up.

Johnny’s gametes

                 

                                          Jenny’s gametes

6) What are the genotypic ratios expected for the offspring of the cross? In other words, how many of each genotype (homozygous dominant, homozygous recessive, heterozygous) are there? List the gene symbols and corresponding number for each genotype.

7) What are the phenotypic ratios expected for the offspring of the cross? In other words, how many of each phenotype (purple, white) are there?

8) You plant some of Johnny and Jenny’s offspring. Two in particular become your favorite plants and you name them Jamie and Josie. You decide to cross these two plants together (you can cross siblings in plants, but this is not really something that occurs very often in humans for various reasons!). Place the gametes that would result from meiosis in Jamie and Josie in the top row for Jamie and left column for Josie of the Punnett square. Then copy and paste the Punnett square below into your lab write up.

                                                                                    Jamie’s gametes

                 

                                          Josie’s gametes

9) What are the genotypic ratios expected for the offspring of the cross?

10) What are the phenotypic ratios expected for the offspring of the cross?

Answer 1

Starting with what is homozygous and heterozygous . Homozygous means a gene with same Alleles . So homozygous fominant will be a pair of dominant alleles . So for flower color homozygous dominant is PP.

Homozygous recessive is ,allele pair with both revessive alleles so it will pp for flower color .

Heterozygous means the allele pair has one dominanant allele and one recessive allele . So for flower color it will be Pp. Now in Heterozygous condition the dominant allele and trait are expressed . So for a flower with genotype Pp , phenotype will be purple . The dominant P causes purple here by supressing the white color of p allele which is Recessive.

Ans 4.

Parents - homozygous dominant × homozygous recessive.

- PP x pp

Gametes - Johnny - P. And jenny - p

F1-

Johny ---->	P	P
Jenny
p	Pp	Pp
p	Pp	Pp

All offsprings are heterozygous and purole flowered.

Genotypic ratio - Pp :Pp: Pp: Pp

So 1:1:1:1

Phenotype - all 4 - purple so phenotypic ratio is 1:1:1:1.

Ans 7-

F2- Pp. X Pp

	P	p
P	PP	Pp
p	Pp	pp

Genotypic ratio - PP: Pp : pp

So 1:2:1

Now , phenotypic ratio - purple : white

So 3:1.

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