Plant Genetics Lab

Plant Genetics

Raphael Van Oostrum

Biology 1/2

Experiment 6

9-21-12

Abstract:

There are three purposes to this lab, the first purpose of this lab is to predict the genetic frequency of offspring in a monohybrid cross. The second purpose of this is to predict the outcomes of genetic crosses using Punnett squares. The third purpose of this lab is to statistically analyze the results of a genetic cross. The results in this lab is with the tobacco seeds color yellow to green it was 74% to 26%. With the Purple to Yellow kernels in the corn was 69% to 31%. Lastly the result of Smooth to Wrinkled is 67% to 33%.

Purpose/

Hypothesis:

The correct purpose of this lab is to understand the genetic code of the tobacco seedlings, the yellow and purple corn, and the smooth and wrinkled corn. My hypothesis of the tobacco seedlings was that 50 of them were going to grow, 17 of them were going to be green, and 33 of them were going to be yellow.

Procedures:

Exercise 1: Observing a Monohybrid Cross

Cut a piece of paper towel to fit inside a petri dish.

Place the paper towel inside the petri dish and moisten with water.

Sprinkle all of the seeds onto the paper towel and then cover the petri dish.

Place seeds near a warm window with indirect light.

Observe seeds for germination each day, and moisten the paper towel as needed.

Create a Punnett square that shows the possible outcomes from a cross between a heterozygous male and a heterozygous female.

Write a hypothesis, using the Punnett square to determine the approximate number of seedlings that will have a dominant trait and that will have a recessive trait out of the 50 seeds.

Once the majority of the seeds have germinated, remove the lid of the petri dish and count the number of seedlings that are green versus those that are yellow.

Compare the extended outcome to actual results found in Data Table 2.

Exercise 2: Dihybrid Crossing with Corn

Count the number of purple and yellow kernels on the ear of corn between the lines in Figures 4-7

Record the data.

Count the number of smooth and wrinkled seeds on the ear of corn.

Record the data.

Construct a Punnett square using Data Table 5.

A dihybrid cross involves two alleles, such as PpS, which represents a heterozygous dihybrid.

The ear of corn is a result of a cross between plants that were both heterozygous for color and texture written as PpSs.

Place these gametes into the Punnett square in Data Table 5 for both the male and female.

Calculate the phenotypic ratios that are expected to be found for each type of seed.

Count the number of each on the quarter ear of corn and record the numbers.

Data/

Observations:

Exercise 1: Observing a Monohybrid Cross

Father (GG) × Mother (gg)

Data Table 1: Punnett Square.

Father (♂)

Gametes G g

Mother (♀) G GG Gg

g Gg gg

Data Table 2: Seedling Data.

Seedling Color Seedling Color

Green Yellow 50%