SBI4U – Grade 12 University Biology
Name:
Date:
Molecular Genetics Unit Test
/10C
/20 KU
/13 TI
/22 A
Multiple Choice Answers: [15 KU]
Select the best answer by circling the letter corresponding to the question on the multiple choice question sheet. DO
NOT write on the multiple choice question sheet.
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Modified True False Answers: [5 KU]
Question True
False
Correction
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Diagram: [10C]
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Short Answer: [13 TI]
1.
Explain why DNA fragments can be separated using an electric current. How does the size of the fragment affect how far it
travels? [3 I]
2.
Using the original mRNA strand below, analyze the other mRNA strands to determine what kind of mutation is presented.
(write out your amino acid sequence for each)
ORIGINAL mRNA: 5`- AUG UAC GCU CCA AGU UAG – 3`
a.
5`- AUG UAC GCU CCC AGU UAG – 3` [2 I]
b.
5`- AUG UAC GCU CCA GU UAG – 3` [2 I]
c.
5`- AUG UAGC GCU CCA AGU UAG – 3` [2 I]
3.
Using the picture below, explain which strand Okazaki fragments would be formed on, and why. [2 I]
4.
Draw a picture of a tRNA molecule. The anticodon for this tRNA molecule is CAU. Include labels for : 5`, 3`, anticodon and
amino acid. [4 C]
5.
You were hired by Oakville Police Services to collect and analyze samples of DNA from a crime scene. Unfortunately, you
only found one hair from the suspect at the crime scene. Your team was hoping to use any samples to conduct several DNA
tests, but will not have enough DNA from the one hair. How could you produce more of the DNA from the sample? Is this
process the same as DNA that occurs in living cells? [5 I]
Long Answer: [22 A]
1.
Explain what would happen in each of the following situations during DNA replication:
a. DNA polymerase III was malfunctioning. [2 A]
b. DNA polymerase I was increased, but ligase was removed. [2 A]
c. Single stranded binding proteins were denatured. [2 A]
d. Primase was increased but helicase was decreased. [2 A]
2.
What would happen in each of these situations during protein synthesis?
a. 5`cap was not added to mRNA [2 A]
b. Aminoacyl-tRNA synthetase was removed [2 A]
c. Something blocked the A site of the ribosome during translation. [2 A]
d. The spliceosomes were not functioning. [2 A]
3.
How could RFLPs be used to determine if a patient has a genetic disease such as Huntington’s? [3 A]
4.
If a mutation caused a change in the shape of the LacI repressor protein, what would the effect on the operon system be?
[3 A]
SBI4U – Grade 12 University Biology Question Sheet
Multiple Choice:
1.
Which of the following is not needed for DNA replication?
a. Ribosomes
b. Nucleotides
c. Enzymes
d. All of the above are needed
2.
DNA replication is said to be semi-conservative. This means that:
a. Half of the old strand is degraded and half is used as a template for the replication of a new strand.
b. One of the two resulting double helices is made up of 2 old strands and the other is made of 2 new strands.
c. Each new double helix consists of 1 old and 1 new strand.
d. One strand of the new double helix is made of DNA and the other strand is made of RNA
3.
The two strands of a DNA double helix are antiparallel. This means that:
a. The two strands are mirror images of each other.
b. Only one of the two strands can be used as a template for replication, since DNA polymerase only works in one
direction
c. One strand runs in the 5`to 3`direction and the other runs in the 3`to 5`direction.
d. They both run in the 3`to 5`direction.
4.
Beginning with the formation of replication bubbles, which of the following is the correct sequence of enzymes use for the
synthesis of the lagging DNA strand?
a. Helicase, primase, DNA polymerase III, DNA polymerase I and ligase
b. Helicase, DNA polymerase I, primase, DNA polymerase III and ligase
c. Primase, DNA polymerase III helicase, DNA polymerase I and ligase
d. Polymerase I, ligase, primase, DNA polymerase III and helicase
5.
After an mRNA molecule is transcribed from a eukaryotic gene, portions called _____ are removed and the remaining _____
are spliced together to produce an mRNA molecule with a continuous coding sequence.
a. Operators…promoters
b. Exons…introns
c. Silencers…enhancers
d. Introns…exons
6.
Restriction endonucleases bind to the _____ on DNA.
a. Promoter
b. TATA box
c. Recognition site
d. 5` cap
7.
During PCR, heat (94-96°C) is used to:
a. Break hydrogen bonds.
b. Break covalent bonds.
c. Accelerate chemical processes.
d. Anneal DNA primers to the single-stranded DNA
8.
The trp-operon:
a. Is repressed by high levels of tryptophan.
b. Consists of 5 genes
c. Uses tryptophan as a corepressor
d. Is an example of negative feedback
e. None of the above
f. All of the above
9.
Sticky ends:
a. Occur when peptide bonds are broken in the DNA double helix by a restriction enzyme.
b. Never occur in eukaryotic DNA
c. Anneal to free ribonucleoside triphosphates.
d. Have nucleotides that are missing their respective complimentary bases.
e. All of the above
f. None of the above
10. What does the central dogma specify?
a. mRNA sequences encode DNA, which encode for proteins
b. Genes are encoded in the nucleus
c. mRNA plays a major role in gene expression
d. A DNA sequence encodes an mRNA sequence that encodes a protein
e. An mRNA sequence encodes protein that encodes DNA
11. Why can`t you figure out the original genetic code of DNA from the polypeptide chain?
a. Uracil replaces Thymine
b. Redundancy of the genetic code
c. The central dogma
d. Introns have been removed
e. A and C are correct
f. B and D are correct
12. What is the role of polymerase I in DNA replication?
a. Keeps strands of double helix from coming back together
b. Unwinds double stranded DNA
c. Removal of primers
d. Sticks okazaki fragments together
13. Which statement about gel electrophoresis is true?
a. DNA migrates toward the negative electrode at the opposite end of the gel.
b. The DNA solution containing fragments to be separated are mixed with loading dye containing methylase.
c. Smaller fragments experience more resistance that larger fragments.
d. DNA migrates toward the positive electrode at the opposite end of the gel.
14. How many copies of a gene would we expect from a PCR reaction after 4 rounds?
a. 2
b. 46
c. 16
d. 8
15. What is the function of the enzyme methylase?
a. Adds 5`cap to mRNA
b. Protects DNA from degradation by adding methyl group
c. Degrades methyl groups
d. Removes introns from mRNA
Modified True and False
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5.
If the sequence in one strand of the DNA helix is 5`- ACGTTG – 3`, then the complimentary sequence of the opposite strand
is 5`- UGAUUC – 3`.
Experiments conducted by Hershey and Chase showed that DNA, not protein, was in fact the hereditary material found in
all cells.
Gel electrophoresis separates DNA fragments on the basis of their size.
Cytosine and Thymine are purines.
The processes of PCR and DNA replication are identical.