Genetic_crosses_lab_6 Fall

27 Jun Genetic_crosses_lab_6 Fall

Question
Lab 6: Genetic Crosses

Name: ______________________________

Lab section: ____________

Lab Instructor’s name: _____________________

Last 4 digits of your CUNYFirst Empl ID #: _____________

Fall 2014

Read Chapter 7 and print out the sample genetic cross posted below the lab on the portal, to use as a guide.

Below is a list of the phenotypes used in this lab. These are all single gene traits that show complete dominance. Use this information to set up and analyze your crosses.

Trait

Dominant phenotype

Recessive Phenotype

Flower color

Purple flowers

White flowers

Plant Height

Tall plants

Short Plants

Seed Shape

Smooth seeds

Wrinkled seeds

Seed Color

Yellow seeds

Green seeds

Part I: Symbols and definitions:

1. a) What is an allele? What is a gene? Give an example of 2 alleles of a human gene. (0.5 pts)

b) What is the difference between an organism that is a homozygote and one that is a heterozygote? (0.25 pts)

c) What is the difference between an organism’s genotype and its phenotype? (0.25 pts)

2. For each trait in the table below, indicate ALL OF THE GENOTYPESthat are possible. Use the first letter of the dominant trait to indicate the trait. (2pts)

Trait

Dominant genotype(s)

Recessive genotype(s)

Flower color

Purple =

White =

Plant Height

Tall =

Short =

Seed Shape

Smooth =

Wrinkled =

Seed Color

Yellow =

Green

Pick three of the crosses to complete using any 3 of the last 4 digits of your CUNYFirst BC student Empl ID. If there are repeats, pick random numbers, so you are doing 3 different crosses. Circle the numbers of the crosses you are doing in column 1 below.

You must pick 3 different crosses. If there are multiple repeated numbers in your ID, pick additional numbers of your choice.

Cross Number

Male parent traits

Female parent traits

0

Heterozygous for flower color

Heterozygous for height

Homozygous dominant for flower color

Heterozygous for height

1

Heterozygous for flower color

Homozygous dominant for height

Heterozygous for flower color

Homozygous dominant for height

2

Heterozygous for flower color

Heterozygous for seed color

Heterozygous for flower color

Heterozygous for seed color

3

Homozygous recessive for flower color

Heterozygous for seed color

Homozygous dominant for flower color

Heterozygous for seed color

4

Homozygous recessive for seed shape

Homozygous recessive for height

Heterozygous for seed shape

Heterozygous for height

5

Heterozygous for seed shape

Heterozygous for height

Heterozygous for seed shape

Homozygous recessive for height

6

Homozygous dominant for flower color

Homozygous recessive for seed shape

Homozygous recessive for flower color

Homozygous dominant for seed shape

7

Heterozygous for flower color

Homozygous recessive for seed shape

Heterozygous for flower color

Homozygous recessive for seed shape

8

Heterozygous for seed shape

Heterozygous for seed color

Homozygous recessive for seed shape

Homozygous dominant for seed color

9

Heterozygous for seed shape

Homozygous recessive for seed color

Homozygous recessive for seed shape

Homozygous recessive for seed color

Now you can use the charts and Punnett squares on each of the following pages to complete your crosses. You can use the sample of a genetic cross posted on the BioPortal directly below the lab for a guide in doing these crosses.

Cross 1: Please write the number of the cross you are performing: ______________

Then fill in the genotype and phenotype for each parent below. Use the sample of a genetic cross posted on the portal directly below the lab for a guide.

Sex

Genotype

Phenotype

Male

Female

Step 1: Determine the different gamete combinations that each parent can contribute to the offspring. Check the hint from the sample problem when you are doing this.

Sex

Gamete 1

Gamete 2

Gamete 3

Gamete 4

Male

Female

Step 2: Fill in the Punnett Square below

Male gametes place across à

Female Gametes:

Place below: ?

Step 3: Find the Phenotype of each of the 16 combinations in your Punnett Square page.

Phenotype you’ve found in offspring

Number of offspring with this phenotype

Cross 2: Please write the number of the cross you are performing: ______________

Then fill in the genotype and phenotype for each parent below.

Sex

Genotype

Phenotype

Male

Female

Step 1: Determine the different gamete combinations that each parent can contribute to the offspring.

Sex

Gamete 1

Gamete 2

Gamete 3

Gamete 4

Male

Female

Step 2: Fill in the Punnett Square below

Male gametes place across à

Female Gametes:

Place below: ?

Step 3: Find the Phenotype of each of the 16 combinations in your Punnett Square page.

Phenotype you’ve found in offspring

Number of offspring with this phenotype

Cross 3: Please write the number of the cross you are performing: ______________

Then fill in the genotype and phenotype for each parent below.

Sex

Genotype

Phenotype

Male

Female

Step 1: Determine the different gamete combinations that each parent can contribute to the offspring.

Sex

Gamete 1

Gamete 2

Gamete 3

Gamete 4

Male

Female

Step 2: Fill in the Punnett Square below

Male gametes place across à

Female Gametes:

Place below: ?

Step 3: Find the Phenotype of each of the 16 combinations in your Punnett Square page.

Phenotype you’ve found in offspring

Number of offspring with this phenotype

Questions:

1. Are gametes haploid or diploid? What about the offspring, are they haploid or diploid? (1pt)

2. a) Can two purple flowered and yellow seeded parents produce offspring that have white flowers and green seeds?

Explain using a Punnett square why you think this outcome is possible or not. (1 pt)

b) Can two short and green seeded parents produce offspring that are tall and have yellow seeds?

Explain using a Punnett square why you think this outcome is possible or not. (1 pt)