Chapter 6 Test
K/U
Name:____________________________________
/24 marks
Comm
/7 marks
App
/24 marks
T/I
/13 marks
Multiple Choice (24 Marks) K/U
1. A chromosome is able to maintain its structure due to which of the following?
a. The genome groups the chromosomes
b. Centriole prevents the chromosomes from separating
c. The special protein that forms the central core called a histone
d. Centrosomes lock the chromosomes together
2. How are the paired bases of a DNA molecule best described?
a. Complementary
b. Covalently linked across the double helix
c. Mirror images
d. Identical
3. During DNA replication, the function of RNA primers is to:
a. Serve as a binding site for DNA ligase
b. Serve as starting points for DNA strand elongation be DNA polymerase III in prokaryotes
c. Serve as starting points for DNA strand elongation by DNA polymerase I in the 3’-5’ direction
d. Open replication bubbles
4. Using the following diagram, in a DNA nucleotide, the number 3 carbon of the
deoxyribose sugar bonds with which of the following?
a. A phosphate of another nucleotide
b. A nitrogenous base
c. Two OH groups
d. Carboxyl group
5. During DNA replication, one of the new strands of DNA is synthesized continuously. The other strand is synthesized
as a number of separate fragments of DNA that are subsequently linked by DNA ligase. Why does this occur?
a. RNA primers only anneal to one of the parental strands of the DNA
b. One of the parental strands in unwound slower than the other by helicase
c. DNA polymerase III only synthesizes DNA in the 3’-5’ direction
d. DNA polymerase III only synthesizes DNA in the 5’-3’ direction
6. Why is DNA replication considered to be semi-conservative?
a. Each original DNA strands makes a copy of its complementary base pair
b. Each original DNA strands makes a copy of itself
c. It keeps half of the old nucleotides
d. Parent strands are anneal back together after replication has occurred
e. None of the above
7. Which enzyme separates and unwinds the DNA strands at the beginning of replication?
a. Helicase b. ligase c. gyrase d. topoisomerase e. DNA polymerase I
8. Which enzyme separates one strand of the DNA strands and relieves the tension caused by unwinding it?
a. Helicase b. ligase c. gyrase d. topoisomerase e. DNA polymerase I
9. Which enzyme joins Okazaki fragments of DNA at the end of replication?
a. Helicase b. ligase c. gyrase d. topoisomerase e. DNA polymerase I
10. Which of the following is the complementary base pairing of the DNA sequence 5’ ATTCGGCTTA 3’?
a. 3’ TAAGCCGAAT 5’ b. 3’ ATTCGGCTTA 5’ c. 5’TAAGCCGAAT 3’ d. 5’ ATTCGGCTTA 3’
11. During DNA replication, base pair mismatches
a. Allow variations of phenotypes
b. Cause the death of the cell
c. Form mutations that cannot be corrected
d. Are repaired by a series of enzymes
12. Which set of labels is correct for the following diagram of DNA
replicating?
a. X is helicase, D is replication fork, and Z is lagging strand
b. X is helicase, Y is replication fork, and Z is leading strand
c. X is topoisomerase, Y is replication fork, and E is lagging strand
d. X is topoisomerase, D is replication fork, and E is leading strand
13. Which statement about telomeres is true?
a. They prevent the loss of genes from the ends of the chromosomes during replication
b. They are associated with aging
c. They are repeating DNA sequences at the ends of chromosomes
d. All of the above
e. None of the above
14. Which of the following is NOT a requirement for DNA to be genetic material?
a. Carry genetic information
b. DNA replicates
c. Allow for information to change through mutation
d. Govern the expression of genotype
15. DNA replicates through which phase of the cell cycle?
a. G₁ b. G₂ c. S d. Mitosis e. Meiosis
16. Which of the following is NOT a rule of replication?
a. Semi-conservative
b. Starts at the origin
c. Synthesis always in the 3’-5’ direction
d. Semi-discontinuous
e. RNA primers required
Fill in the Blanks (6 Marks) K/U
Compare and contrast DNA to RNA
DNA
RNA
Matching (14 Marks) App
Single-strand binding
protein
Helicase
A
Uses the RNA primer as a starting point to add DNA nucleotides
B
DNA ligase
RNA primer
Topoisomerase
DNA polymerase I
DNA polymeraseII
DNA polymerase III
RNA primase
C
D
E
F
G
H
I
Telomerase
Nucleoside
triphosphate
Okazaki fragments
Solenoid
Nucleosome
J
K
Cuts one of the double strands in front of the replication fork, which allows the strand
to twist and relieve tension
Fills gaps between Okazaki fragments and checks for base pair errors
Builds a small RNA complimentary strand to begin replication
Binds to replication points and separates the double strands
Cluster of 8 histones
Coiled strings of nucleosomes
Proteins that keep the strands from annealing once separated
Molecule that supplies energy by releasing phosphates and then serves as a new
nucleotide during replication
Small fragments built along the lagging strand
DNA sequence found just before the gene allowing RNA polymerase to bind
L Removes and replaces base-pair mismatches
M Acts as starting points for DNA polymerase
N Removes RNA primer on lagging strand and replaces with nucleotides
Labeling (10 Marks) App
Label the following structures that are involved with DNA replication.
Short Answer (20 Marks) T, C
1. Explain why DNA is described as being “replicated” instead of “copied” (1). What is this process referred to as (1)? C
2. If there was a DNA strand that was 50 pairs long, how many nucleotide molecules make up this DNA strand (1)? If
the DNA strand contained 19 adenine bases, predict how many cytosine bases make up this molecule (1).
Explain (1). T
3. What type of bond holds DNA strands together (1)? How many are used to pair A with T (1)? C with G (1)? Using
what you already know about bonding, if two DNA samples are heated to separate strands and one sample
separates at 84⁰C, while the second strand separates at 91⁰C, why would the temperatures be different (1)? T
4. If the fragment of DNA shown below were to replicate, on which strand (A or B) would Okazaki fragments be formed
if the origin of replication is at the left and the replication fork proceeds towards the right (1). Explain your
reasoning (1). T
Origin of replication
Origin of replication
5’ ATCGATCCCTAG 3’
3’ TAGCTAGGGATC 5’
Strand A
Strand B
5. Explain why DNA replication is slightly slower in the lagging strand of DNA than in the leading strand (4). T
6. During replication, telomeres protect chromosomes from losing essential coding DNA. C
a. List 2 important functions of telomeres (2).
b. Why are the ends of eukaryotic chromosomes vulnerable? How do telomeres help (2)?
c. In what ways are telomeres like a biological clock (1)?