Name: ____________________________________________________
(see Chap 13: DNA Structure and Functions; Sylvia Mader)

DNA:  The Molecule of Heredity

1. A nucleotide is made of three parts: a ___________________ group, a five carbon __________________, and a nitrogen containing _____________________

2. In a single strand of DNA, the phosphate group binds to the __________________ of the next group.

3. The 5’ end of a single DNA strand contains a free __________________, while the 3’ end contains a free __________________________.

4. Chromosomes consist of what two substances:  ____________________  &  ______________________

5.  DNA was not thought to be the genetic blueprint originally; instead many scientists hypothesized that _______________________ contained the genetic code and blueprint of life.  (They were later proven wrong.)

6. Purines have _________ rings, and pyrimidines have  ____________ ring.

7. Check each of the following statements that are true with regard to Griffith’s experiments.

a. ______  Griffith discovered transformation in bacteria.
b. ______ Mice injected with non-encapsulated bacteria quickly became sick and died.
c. ______ Encapsulated bacteria can become “naked” bacteria.
d. ______ Bacteria that are naked tend to be harmless.
e. ______ Naked bacteria can develop a capsule only after exposure to the DNA of encapsulated bacteria.
f. ______ Griffith’s transforming factor was the protein in the capsule.
g. ______ Heating the encapsulated bacteria preventing transformation of the naked variety.
h. ______ Transformation allows bacteria to acquire new genes.
i.  ______ Enzymes that destroyed DNA would prevent transformation.

8. Check each of the following statements that are true with regard to the Hershey-Chase experiment.

a. _______ DNA was labeled with radioactive phosphorous.
b. _______ Protein was not labeled.
c. _______ Radioactive sulfur was found in the offspring phages after they emerged from the cell.
d. _______ Phage proteins were not transmitted to host cell or to offspring.

9. Chargaff’s rule states that the DNA of any species contains equal amounts of __________________ & ____________  and also equal amounts of  __________________ &  ____________________

10. Wilkins and Franklin studied the structure of DNA using  _________________________  and determined that the shape of the molecule was a __________________

11. James Watson and Francis Crick amended Franklin and Wilkins’s conclusions and determined that the shape of the molecule was instead a _________________       __________________

12.  In DNA, thymine is complementary to ________________ ; cytosine is complementary to _____________

13. In a strand of DNA, the percentage of thymine is 30 %.  What is the percentage of cytosine in the same DNA strand?  _________________

14. Number the steps of DNA replication in the correct order (1, 2, 3)

_______Polymerase travels down the DNA parent strand from the 3’ to 5’ direction.
______  DNA unwinds
______  Ligase binds okazaki fragments together

15. Why is DNA replication called “semi-conservative”? __________________________________________

16.  What enzyme unwinds or unzips the parent strand?  ________________

17. The junction between separated strands is called the ________________________________

18. What enzyme synthesizes the new DNA strand?  _______________________

19.  What enzyme binds fragments of DNA on the lagging strand?  ______________________

DNA20.  DNA polymerase only travels in the  ________   to  _________  direction.

21.  On the diagram:

Label the 3’ and 5’ ends.

Circle a nucleotide.

Label the sugar and phosphate.

Label the bases that are not already labeled


22. The two sides of the DNA helix are held together by ________________________

23. Write out the complete name for DNA: __________________________________________


24. Name the scientist(s) responsible for each of the following discoveries.

_____________________________________  Bacterial transformation
_____________________________________ The base-pair rule
_____________________________________ DNA was the hereditary material of viruses
_____________________________________ The shape of DNA was a helix
_____________________________________ The shape of DNA was a double helix

25. A permanent change in the sequence of bases is called a(n):  _________________________________
What  process can prevent these errors from occurring?  _____________________________________