CHS Science Dept. Biology
Name: Date: Period:
Watson and Crick’s DNA Model
I. Introduction—you will make a paper model that accurately reflects the first DNA model made by Watson and Crick. Use your model to answer the questions in your lab journal.
II. Model construction—you need ONE sheet for EACH of the six basic molecules needed to make a ‘three rung’ DNA molecule. Anything you do not use can be returned to the appropriate bin.
III. Questions:
1. What is the proper term for a structure that consists of one deoxyribose sugar, one phosphate group (phosphoric acid), and one nitrogen base?
2. What are Adenine, Thymine, Guanine, and Cytosine called?
3. How do the nitrogen bases pair? What in the model helps to make sure the bases pair correctly?
4. How are Guanine and Adenine different than Thymine and Cytosine? How is that shown in the model?
5. What type of bond holds the base pairs together?
6. What do the four nitrogen bases bond to in the DNA helix?
7. Where are the deoxyribose sugar and phosphate group found in relation to the nitrogen bases in the DNA helix?
8. How many nucleotide strands form a single DNA helix?
9. Why are half of your deoxyribose sugars ‘upside down’ in your model? What does that represent in the real DNA molecule?
10. Why did I NOT tell which nitrogen bases to use in your model? Is your nitrogen base sequence different than your table partners? Could this be a CODE?!
CHS Science Dept. Biology
Name: Date: Period:
Watson and Crick’s DNA Model
I. Introduction—you will make a paper model that accurately reflects the first DNA model made by Watson and Crick. Use your model to answer the questions in your lab journal.
II. Model construction—you need ONE sheet for EACH of the six basic molecules needed to make a ‘three rung’ DNA molecule. Anything you do not use can be returned to the appropriate bin.
III. Questions:
1. What is the proper term for a structure that consists of one deoxyribose sugar, one phosphate group (phosphoric acid), and one nitrogen base?
2. What are Adenine, Thymine, Guanine, and Cytosine called?
3. How do the nitrogen bases pair? What in the model helps to make sure the bases pair correctly?
4. How are Guanine and Adenine different than Thymine and Cytosine? How is that shown in the model?
5. What type of bond holds the base pairs together?
6. What do the four nitrogen bases bond to in the DNA helix?
7. Where are the deoxyribose sugar and phosphate group found in relation to the nitrogen bases in the DNA helix?
8. How many nucleotide strands form a single DNA helix?
9. Why are half of your deoxyribose sugars ‘upside down’ in your model? What does that represent in the real DNA molecule?
10. Why did I NOT tell which nitrogen bases to use in your model? Is your nitrogen base sequence different than your table partners? Could this be a CODE?!