Bio 111B

Study Questions 13: DNA, Replication & DNA Technology I

 

1. What information do genes carry?

 

2. How are DNA, enzymes, and metabolic pathways related?

 

3. How do alleles differ at the DNA level? at the protein level? at the phenotype level?

 

4. Why do we say that a DNA double helix runs antiparallel?

 

5. What is the importance of complementarity to replication?

 

6. What are the functions of DNA polymerase, RNA polymerase, and ligase?

 

7. What is a replication fork?

 

8. Why is there a leading strand and a lagging strand? What are each of their polarities?

 

9. What are Okazaki fragments? Why are they formed?

 

10. Why do we call DNA synthesis semi-conservative?

 

11. What is a restriction enzyme? Where are they naturally found? What is their natural function?

 

12. Which way does DNA move in an electrical field and why does it move? How does gel electrophoresis separate DNA molecules? How do we make the DNA visible in an electrophoresis gel?

 

13. What is PCR? Why is it useful to so many applications, from molecular genetics to forensic pathology? What enzyme is used in PCR and why?

 

14. In the following diagram, an origin of replication is shown. On the diagram,

a. in the boxes, label the remaining polarities of the DNA

b. indicate in which segments DNA synthesis will be continuous and in which it will be discontinuous

c. indicate the direction in which DNA polymerase will elongate the newly-made DNA

 

 

15. If one single strand of DNA has a ratio of purines to pyrimidines of 0.5, what is the ratio of purines to pyrimidines in the complementary strand?

 

16. If a single strand of DNA has a C+T proportion of 0.2 (there are 20% C's and T''s in that strand), the C+T proportion in the complementary strand is…

a. 0.2

b. 5.0

c. 0.8

d. 1.25

e. impossible to determine from the information given

 

17. Consider the following gel of a drop of blood from the perpetrator (P) left at the scene of a crime and blood samples of the 3 prime suspects (S1, S2 & S3).

a. Which suspect is the perpetrator? Explain how you know.   b. What procedures were likely applied to the crime scene blood sample to be able to produce this gel?

18.Once again, two men were involved in a paternity suit brought by a woman against her estranged husband. The woman was seeking child support for her infant from her husband, but the husband accused the woman's lover of being the biological father. Unfortunately, blood typing was inconclusive: both men had the same blood type. So the judge ordered DNA analysis. A sample of blood was taken from the mother, the baby, and both men. The results are shown below.

a. With this information, who is the father of the baby?   b. Which bands (1-11) are most useful for determining the father of the baby? Why?