Lab 6: Genetic Crosses
Spring 2014
Read Chapter 7 and print out the sample genetic cross 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
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? Give an example of 2 alleles of any gene. (0.5 pts)
An allele is a trait of the gene. Individuals has two copies of each gene inherent from both parents. Example of 2 alleles for a gene could be the blood type or eye color
b) What is the difference between an organism that is a homozygote and one that is a heterozygote? (0.25 pts)
Homozygote individual inherits the same two alleles for this gene, and Heterozygote individual inherits different alleles from each parent.
c) What is the difference between an organism’s genotype and its phenotype? (0.25 pts)
The Phenotype is the outward appearance of an individual, and the Genotype is the organism’s genetic composition.
2.) For each trait indicate the genotypes that 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 student 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 Homozygous dominant for height |
Heterozygous for flower color Homozygous dominant for height |
1 |
Heterozygous for flower color Heterozygous for height |
Homozygous dominant for flower color Heterozygous for height |
2 |
Heterozgyous for flower color Heterozygous for seed color |
Heterozgyous 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 Homozygous recessive for seed color |
Homozygous recessive for seed shape Homozygous recessive for seed color |
9 |
Heterozygous for seed shape Heterozygous for seed color |
Homozygous recessive for seed shape Homozygous dominant for seed color |
Now you can use the charts and Punnett squares on each of the following pages to complete your 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 problem 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 tall and smooth seeded parents produce offspring that are short and have wrinkled seeds? (To receive a full credit for this assignment you MUST explain your answers for part A and part B by drawing the respective Punnett squares for each of your answers).
Explain using a Punnett square why you think this outcome is possible or not. (1pt)
B) Can two white flowered and green seeded parents produce offspring that have Purple flowers and have yellow seeds?
6 years ago
Delivering a high-quality product at a reasonable price is not enough anymore.
That’s why we have developed 5 beneficial guarantees that will make your experience with our service enjoyable, easy, and safe.
You have to be 100% sure of the quality of your product to give a money-back guarantee. This describes us perfectly. Make sure that this guarantee is totally transparent.
Read moreEach paper is composed from scratch, according to your instructions. It is then checked by our plagiarism-detection software. There is no gap where plagiarism could squeeze in.
Read moreThanks to our free revisions, there is no way for you to be unsatisfied. We will work on your paper until you are completely happy with the result.
Read moreYour email is safe, as we store it according to international data protection rules. Your bank details are secure, as we use only reliable payment systems.
Read moreBy sending us your money, you buy the service we provide. Check out our terms and conditions if you prefer business talks to be laid out in official language.
Read more