Label this strand "chimpanzee DNA." This strand represents a small section of the gene that codes for chimpanzee hemoglobin protein.

  • Group member 3

Synthesize a strand of DNA that has the following sequence:

Label this strand "gorilla DNA." This strand represents a small section of the gene that codes for gorilla hemoglobin protein.

  • Group member 4

Synthesize a strand of DNA that has the following sequence:

Label this strand "common ancestor DNA." This DNA strand represents a small section of the gene that codes for the hemoglobin protein of a common ancestor of the gorilla, chimpanzee, and human.

Hybridization data for human DNA

Human DNA compared to:

Number of matches

Unmatched bases

Chimpanzee DNA

 

 

Gorilla DNA

 

 

Data for common ancestor DNA

Common ancestor DNA compared to:

Number of matches

Unmatched bases

Human DNA

 

 

Chimpanzee DNA

 

 

Gorilla DNA

 

 

(You will use this strand in Part III.) Emphasize to students that they will be using a model constructed from hypothetical data in the case of the common ancestor, since no such DNA yet exists, but that the other three sequences are real.

Step 2. Students should compare the human DNA to the chimpanzee DNA by matching the strands base by base (paper clip by paper clip).

Step 3. Students should count the number of bases that are not the same. Record the data in a table. Repeat these steps with the human DNA and the gorilla DNA.

The data for the hybridizations are as follows: chimpanzee DNA, 5 unmatched bases; gorilla DNA, 10 unmatched bases. Be sure to ask the students to save all of their DNA strands for Part III.

Evaluate

  1. How do the gorilla DNA and the chimpanzee DNA compare with the human DNA?

    The human DNA is more similar to the chimpanzee DNA than the gorilla DNA.

  2. What do these data suggest about the relationship between humans, gorillas, and chimpanzees?  

    The data suggest that humans are more closely related to the chimpanzee than they are to the gorilla.

  3. Do the data support any of your hypotheses? Why or why not?  



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