Question

Question 1

Complementary base pairing is the result of

Question 1 options:

	hydrogen bonding
	the fact that complementary bases fit together physically
	covalent bonding
	ionic bonding
	the fact that strands of DNA are wound around each other in a double helix

Question 2

During DNA replication, the function of RNA primers is to

Question 2 options:

	open replication bubbles
	serve as starting points for DNA strand elongation by DNA polymerase I in the 3' - 5' direction
	serve as starting points for DNA strand elongation by DNA polymerase III
	prevent new-separated strands of DNA from rejoining
	serve as a binding site for DNA ligase

Question 3

Which of the following is a correct representation of a segment of DNA?

1.	5'ATTC3' 3'ATTC5'	4.	5'ATAG3' 3'TATC5'
2.	5'AUUC3' 3'UAAG5'	5.	5'ACGA3' 3'TGCT5'
3.	5'CCGG3' 5'GGCC3'

Question 3 options:

	1
	1 and 3
	2 and 3
	4 and 5
	5 and 1

Question 4

A DNA nucleotide contains
1.      a cyclic nitrogen-containing part
2.      a single ring containing five carbons
3.      a part which contains four oxygen atoms surrounding a central atom.

In order, 1, 2 and 3 are

Question 4 options:

	a base, a phosphate group, a sugar
	a sugar, a base, a phosphate group
	a base, a sugar, a phosphate group
	a phosphate group, a sugar, a base
	a sugar, a phosphate group, a base

Question 5

5'GGCATA(X)
(Z)CCGTAT(Y)

If the above is a representation of a piece of double-stranded DNA, what symbols should occupy the positions (X),(Y) and (Z)?

Question 5 options:

	3',3',5'.
	5',3',3'
	5',3',5'
	5',5',3'
	3',5',3'

Question 6

If the percentage composition of thymine in a DNA molecule is 22%, what is the percentage composition of cytosine?

Question 6 options:

	28%
	32%
	26%
	22%
	18%

Question 7

If a free phosphate is found at the 5' end of a DNA strand, what is found at the other end of the same strand?

Question 7 options:

	a hydroxyl group on the 5' carbon of a deoxyribose sugar
	a hydroxyl group on the 3' carbon of a deoxyribose sugar
	a phosphate group on the 5' carbon of a deoxyribose sugar
	a phosphate group on the 3' carbon of a deoxyribose sugar
	a base attached to the 3' carbon of a deoxyribose sugar

Question 8

A mutant form of E. coli has been discovered in which replication is unsuccessful because the RNA primer is not released from the template strand. Which enzyme do you think is nonfunctional?

Question 8 options:

	DNA polymerase III
	primase
	ligase
	helicase
	DNA polymerase I / RNAase H

Question 9

The paired bases of a DNA molecule are best described as

Question 9 options:

	covalently linked across the width of the double helix
	identical
	mirror images
	complementary
	single-stranded

Question 10

In what order do the following molecules become involved in DNA replication?
1.      single-stranded binding proteins
2.      DNA polymerase III
3.      primase
4.      helicase

Question 10 options:

	4,1,3,2
	4,3,1,2
	1,3,4,2
	3,2,4,1
	2,3,4,1

Answer 1

1. Complementary base pairing is the result of Hydrogen bonding between the complementary bases in the DNA structure.

2. During DNA replication, the function of RNA primers is to serve as starting points for DNA strand elongation by DNA polymerase III. This short RNA primer provides the free 3'OH which required for DNA pol to work.

3. 4 and 5 is the correct representation of the segment of DNA.

4. a base, a sugar, a phosphate group, and this the part of nucleotide which is building block of DNA.

5. 3',5',3'

6. 28% cytosine will be there because according to chargaff's rule the composition of bases in DNA would be A=T and C=G

7. a hydroxyl group on the 3' carbon of a deoxyribose sugar

8. DNA polymerase I / RNAase H

9. complementary

10. 4,1,3,2