DNA Structure and Replication Review:

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. Chargaff's rule states that the DNA of any species contains equal amounts of

______& ______

and also equal amounts of

______& ______

4. In DNA, thymine is complementary to

______;

cytosine is complementary to ______

5. In a strand of DNA, the percentage of thymine is 30 %. What is the percentage of cytosine in

the same DNA strand? ______

6. James Watson and Francis Crick with the help of Rosalind Franklin and others, determined that

the shape of the molecule was a ______

7. On the diagram:

Circle and label a nucleotide.

Label the sugar and phosphate molecules.

Label the bases that are not already labeled

Label a base pair.

Label the sugar-phosphate backbones.

Label the “ladder rungs” of base pairs.

Label the hydrogen bonds.

DNA Replication

8. For the following diagrams, build the new halves that will result.

DNA Replication

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

______Daughter strands are formed using complementary base pairing.
______DNA unwinds
______The DNA of the daughter strands winds with together with its parent strand.

10 . Why is DNA replication called "semi-conservative"? ______

11. What enzyme unwinds or unzips the parent strand? ______

12. What enzyme connects the new bases to the old bases? ______

13. What enzyme connects the nucleotides together? ______

14 . In DNA, Adenine pairs with ______and Cytosine pairs with

______.

15. Show the complimentary base pairing that would occur in the replication of this short DNA molecule. Use a colored pencil to show which strands are the original and which are newly synthesized.

Original DNA Strand 1 / Original DNA Strand 2 / ------> / Original DNA Strand 1 / New DNA Strand / + / New DNA Strand / Original DNA Strand 2
A - / T
C - / G
T - / A
T - / A
A - / T
C - / G
G - / C
C - / G
C - / G
G - / C
A - / T
T - / A