GENETIC ANALYSIS OF HYBRID CORN page 28

Equipment: floppy disk (student provides)

Computer lab to provide each student with a computer

Dihybrid cross corn (yellow/purple:starchy/wrinkled) for each student

There are two stages to this exercise:

1) Setting up the spread sheet in the computer lab to perform ² analysis

2) Scoring corn kernals, and entering the data into your spread sheet.

I. Setting up the spread sheet (conducted in the computer lab)

• Have students unfamiliar with spread sheets sit in row adjacent to demo computer. Possibly work in pairs on the first time through the process.

b. Each student should bring a formatted floppy to this lab on time (cannot start until everyone is present).

c. Start with a fresh Lotus screen, each person places data and formulae in identical addresses.

• Carefully follow directions on how to set up of the spread sheet.
• Give all students the same two sets of data to analyze.

II. Count the corn

Place on each desk (pair of students) one each of ears of corn showing these ratios of progeny:

9:3:3:1

1:1:1:1

9:7

13:3

9:3:4

For 9:3:3:1 of yellow/purple:starchy/sweet corn:

• Record number of the cob being counted (should be written on the end).

• Note mark at end of corn to designate initial row.
• Count kernals using the clicker counter: use index finger to indicate the kernal being counted, the middle finger (or thumb) to depress the counter.
• Count all YS, the Ys then yS then ys.
• Enter the data into the spread sheet to perform ² analysis

1) Each student will be assigned to count classes of all kernals of one ear from the above crosses.

2) Then, each student should count a single row of each of the five different crosses of corn.

3) Then Chi Squared analysis is performed to see if the genes arestatistically linked.