SCIN130 Lab 6: The Origin of Corn

SCIN 130 Lab 6: The Origin of Corn

 

General Instructions

 

Be sure to read the general instructions from the Lessons portion of the class prior to completing this packet.

 

Remember, you are to upload this packet with your quiz for the week!

 

Background

Ten thousand years ago, corn didn’t exist anywhere in the world, and until recently scientists argued vehemently about its origins. Today the crop is consumed voraciously by us, by our livestock, and as a major part of processed foods. So where did it come from? Popped Secret: The Mysterious Origin of Corn tells the story of the genetic changes involved in the transformation of a wild grass called teosinte into corn.

 

 

 

Specific Lab Instructions

 

Name:

Date:

 

Go to: The Mysterious Origin of Corn from HHMI Biointeractive

 

Watch the short film, and answer these questions as you progress.

 

1. What was the purpose of domestication in ancient civilizations?

 

2. What TWO features made Dr. Beadle believe that teosinte was an ancestor of modern maize?

1.

2.

3. Stop the film at the 6:55 and answer the following:

a. Answer the Let’s Review Questions. Embed a screenshot of your answer to question 1 in this packet:

Question 1:

 

b. Why did botanists expect the wild relative of maize to look similar to modern maize?

 

c. Why did Dr. Beadle use so many plants in his experiments? Would his data have been as meaningful if he had grown only 1,000 plants? Why or why not?

d. How many genes did Dr. Beadle deduce were involved in the changes between maize and teosinte?

4. Resume the film. Near what river did Dr. Doebley discover that all modern maize varieties originate?

5. What type of evidence left behind on the plant grinding tools was Dr. Piperno looking for to show the presence of maize?

6. Stop again at 12:10 and answer the following

a. How did archaeological evidence support the molecular evidence for the timing and geographic location of maize domestication?

b. Based on the quiz in the video, Dr. Doebley and his team compared the DNA sequence of maize to that of a number of teosinte varieties from throughout Mexico. What did their analysis reveal? Select all that apply.

|_|That teosinte and maize have the same number of chromosomes.

|_|That maize originated from a variety of teosinte that existed about 9,000 years ago.

|_|That maize and teosinte could interbreed to produce viable hybrid plants.

|_|That maize is most closely related to a teosinte variety in the Balsas region of Mexico.

 

7. Watch the film to the end.

a. Fill in the table below to compare teosinte and maize.

	Extent of branching	Number of rows of kernels per cob	Kernel type (naked or enclosed in a hard fruitcase)
Teosinte
Maize

b. Pick one of the characteristics of maize from the table above and explain how it makes the crop more useful to humans than teosinte?

 

c. What does the fact that teosinte can be “popped” help to explain?

 

 

 

 

8. Explain how changes in a small number of genes can result in very different looking plants.

 

 

 

Adapted from:

Rice, E. (2016). Keep, S., Bonetta, L., Beardsley, P. & York, A. (Eds). Click and Learn “The Mysterious Origin of Corn.” HHMI Biointeractive Teaching Materials.

Additional References:

Beadle, G.W. (1977). “The origin of Zea mays.” In Origins of Agriculture, edited by C. E. Reed, 615–535. The Hague: Mouton.

 

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