Cornell BIOMG 1350 Prelim 3 Study
Guide – Academic Review & Practice
Questions
BIOMG 1350: Prelim 3 Practice Questions & Answers
Topic 1: Gene Regulation in Prokaryotes (Operons)
1. What is the primary function of a genetic operon in prokaryotes?
a) To speed up the process of DNA replication
b) To allow for the coordinated regulation of a group of genes with a related function ✓
c) To ensure all genes on a chromosome are transcribed at the same rate
d) To prevent mutation in critical metabolic genes
2. In the lac operon, what is the role of the repressor protein when lactose is absent?
a) It activates RNA polymerase.
b) It binds to the operator and prevents transcription. ✓
c) It binds to the promoter and initiates transcription.
d) It digests lactose into glucose and galactose.
3. The molecule allolactose acts as a(n) ______ in the lac operon.
a) inducer ✓
b) corepressor
c) repressor
d) promoter
4. In a lacI- mutant, the lac operon is:
a) Never expressed, even in the presence of lactose.
b) Constitutively expressed, regardless of lactose presence. ✓
c) Expressed only when glucose is present.
d) Repressed by the binding of cAMP-CRP.
5. What is the state of the lac operon when glucose is high and lactose is absent?
a) High transcription
b) Low transcription ✓
c) Moderate transcription
d) Transcription is oscillating
, 6. The CAP-cAMP complex ______ transcription of the lac operon by ______.
a) activates; facilitating RNA polymerase binding to the promoter ✓
b) represses; binding to the operator
c) activates; degrading the repressor protein
d) represses; lowering cAMP levels
7. In the trp operon, tryptophan acts as a(n):
a) inducer
b) corepressor ✓
c) activator
d) inhibitor of replication
8. Attenuation in the trp operon is a mechanism that regulates transcription:
a) After it has already begun. ✓
b) By blocking RNA polymerase from binding.
c) By permanently inactivating the repressor.
d) At the level of translation only.
Topic 2: Gene Regulation in Eukaryotes (Transcription & Chromatin)
9. Which of the following is NOT a common level of gene regulation in eukaryotes?
a) Chromatin remodeling
b) Transcriptional control
c) Operon activation ✓
d) Alternative splicing
10. The acetylation of histone tails generally leads to:
a) Tighter DNA packing and gene silencing.
b) Looser DNA packing and increased transcription. ✓
c) The initiation of DNA replication.
d) The degradation of the nucleosome.
11. DNA methylation at promoter regions is typically associated with:
a) Enhanced transcription initiation.
b) Gene silencing. ✓
c) Recruitment of RNA polymerase II.
d) Histone acetylation.
12. A transcription factor's transactivation domain is responsible for:
a) Binding to a specific DNA sequence.
b) Interacting with other proteins to facilitate transcription. ✓
, c) Ensuring the factor remains in the cytoplasm.
d) Blocking the binding of RNA polymerase.
13. Enhancer elements can be located:
a) Only upstream of a gene's promoter.
b) Only within the first intron of a gene.
c) Thousands of base pairs away from the gene they regulate. ✓
d) Only on the same chromosome as the gene they regulate.
14. The mediator complex primarily functions to:
a) Methylate DNA.
b) Link transcription factors to RNA polymerase II. ✓
c) Degrade mRNA molecules.
d) Act as a ribosome for protein synthesis.
15. Alternative RNA splicing allows for:
a) One gene to code for multiple different proteins. ✓
b) DNA to be replicated in segments.
c) A single mRNA to be translated repeatedly.
d) The creation of operons in eukaryotic cells.
16. What is the role of siRNA (small interfering RNA) in gene regulation?
a) It promotes transcription.
b) It guides the degradation of complementary mRNA sequences. ✓
c) It acts as a transcription factor.
d) It helps in the export of mRNA from the nucleus.
Topic 3: Recombinant DNA Technology & Molecular Cloning
17. Restriction enzymes are crucial in molecular biology because they:
a) Synthesize DNA from an RNA template.
b) Cut DNA at specific recognition sequences. ✓
c) Ligate DNA fragments together.
d) Amplify small amounts of DNA.
18. What is the function of DNA ligase in a cloning experiment?
a) To cut DNA at specific palindromic sequences.
b) To create single-stranded overhangs.
c) To join together DNA fragments with complementary ends. ✓
d) To separate DNA fragments by size using gel electrophoresis.
, 19. A plasmid used as a cloning vector must contain:
a) An origin of replication. ✓
b) A centromere sequence.
c) Telomeres.
d) The entire human genome.
20. What is the purpose of a selectable marker (e.g., an antibiotic resistance gene) on a
plasmid?
a) To allow the plasmid to replicate.
b) To identify cells that have taken up the plasmid. ✓
c) To ensure the plasmid is cut by a restriction enzyme.
d) To code for the protein of interest.
21. In a typical cloning procedure, if you cut a plasmid and a DNA insert with the same
restriction enzyme, you will create:
a) Blunt ends.
b) Complementary sticky ends. ✓
c) Mismatched ends that cannot ligate.
d) RNA primers.
22. The Polymerase Chain Reaction (PCR) is used to:
a) Digest DNA with restriction enzymes.
b) Determine the sequence of a DNA fragment.
c) Amplify a specific segment of DNA. ✓
d) Translate mRNA into protein.
23. Which of the following is NOT required for a standard PCR reaction?
a) DNA template
b) DNA primers
c) Restriction enzymes ✓
d) Thermostable DNA polymerase (Taq)
24. During which step of PCR are the primers extended by DNA polymerase?
a) Denaturation
b) Annealing
c) Extension ✓
d) Ligation
25. Gel electrophoresis separates DNA fragments based on:
a) Charge and size. ✓
Guide – Academic Review & Practice
Questions
BIOMG 1350: Prelim 3 Practice Questions & Answers
Topic 1: Gene Regulation in Prokaryotes (Operons)
1. What is the primary function of a genetic operon in prokaryotes?
a) To speed up the process of DNA replication
b) To allow for the coordinated regulation of a group of genes with a related function ✓
c) To ensure all genes on a chromosome are transcribed at the same rate
d) To prevent mutation in critical metabolic genes
2. In the lac operon, what is the role of the repressor protein when lactose is absent?
a) It activates RNA polymerase.
b) It binds to the operator and prevents transcription. ✓
c) It binds to the promoter and initiates transcription.
d) It digests lactose into glucose and galactose.
3. The molecule allolactose acts as a(n) ______ in the lac operon.
a) inducer ✓
b) corepressor
c) repressor
d) promoter
4. In a lacI- mutant, the lac operon is:
a) Never expressed, even in the presence of lactose.
b) Constitutively expressed, regardless of lactose presence. ✓
c) Expressed only when glucose is present.
d) Repressed by the binding of cAMP-CRP.
5. What is the state of the lac operon when glucose is high and lactose is absent?
a) High transcription
b) Low transcription ✓
c) Moderate transcription
d) Transcription is oscillating
, 6. The CAP-cAMP complex ______ transcription of the lac operon by ______.
a) activates; facilitating RNA polymerase binding to the promoter ✓
b) represses; binding to the operator
c) activates; degrading the repressor protein
d) represses; lowering cAMP levels
7. In the trp operon, tryptophan acts as a(n):
a) inducer
b) corepressor ✓
c) activator
d) inhibitor of replication
8. Attenuation in the trp operon is a mechanism that regulates transcription:
a) After it has already begun. ✓
b) By blocking RNA polymerase from binding.
c) By permanently inactivating the repressor.
d) At the level of translation only.
Topic 2: Gene Regulation in Eukaryotes (Transcription & Chromatin)
9. Which of the following is NOT a common level of gene regulation in eukaryotes?
a) Chromatin remodeling
b) Transcriptional control
c) Operon activation ✓
d) Alternative splicing
10. The acetylation of histone tails generally leads to:
a) Tighter DNA packing and gene silencing.
b) Looser DNA packing and increased transcription. ✓
c) The initiation of DNA replication.
d) The degradation of the nucleosome.
11. DNA methylation at promoter regions is typically associated with:
a) Enhanced transcription initiation.
b) Gene silencing. ✓
c) Recruitment of RNA polymerase II.
d) Histone acetylation.
12. A transcription factor's transactivation domain is responsible for:
a) Binding to a specific DNA sequence.
b) Interacting with other proteins to facilitate transcription. ✓
, c) Ensuring the factor remains in the cytoplasm.
d) Blocking the binding of RNA polymerase.
13. Enhancer elements can be located:
a) Only upstream of a gene's promoter.
b) Only within the first intron of a gene.
c) Thousands of base pairs away from the gene they regulate. ✓
d) Only on the same chromosome as the gene they regulate.
14. The mediator complex primarily functions to:
a) Methylate DNA.
b) Link transcription factors to RNA polymerase II. ✓
c) Degrade mRNA molecules.
d) Act as a ribosome for protein synthesis.
15. Alternative RNA splicing allows for:
a) One gene to code for multiple different proteins. ✓
b) DNA to be replicated in segments.
c) A single mRNA to be translated repeatedly.
d) The creation of operons in eukaryotic cells.
16. What is the role of siRNA (small interfering RNA) in gene regulation?
a) It promotes transcription.
b) It guides the degradation of complementary mRNA sequences. ✓
c) It acts as a transcription factor.
d) It helps in the export of mRNA from the nucleus.
Topic 3: Recombinant DNA Technology & Molecular Cloning
17. Restriction enzymes are crucial in molecular biology because they:
a) Synthesize DNA from an RNA template.
b) Cut DNA at specific recognition sequences. ✓
c) Ligate DNA fragments together.
d) Amplify small amounts of DNA.
18. What is the function of DNA ligase in a cloning experiment?
a) To cut DNA at specific palindromic sequences.
b) To create single-stranded overhangs.
c) To join together DNA fragments with complementary ends. ✓
d) To separate DNA fragments by size using gel electrophoresis.
, 19. A plasmid used as a cloning vector must contain:
a) An origin of replication. ✓
b) A centromere sequence.
c) Telomeres.
d) The entire human genome.
20. What is the purpose of a selectable marker (e.g., an antibiotic resistance gene) on a
plasmid?
a) To allow the plasmid to replicate.
b) To identify cells that have taken up the plasmid. ✓
c) To ensure the plasmid is cut by a restriction enzyme.
d) To code for the protein of interest.
21. In a typical cloning procedure, if you cut a plasmid and a DNA insert with the same
restriction enzyme, you will create:
a) Blunt ends.
b) Complementary sticky ends. ✓
c) Mismatched ends that cannot ligate.
d) RNA primers.
22. The Polymerase Chain Reaction (PCR) is used to:
a) Digest DNA with restriction enzymes.
b) Determine the sequence of a DNA fragment.
c) Amplify a specific segment of DNA. ✓
d) Translate mRNA into protein.
23. Which of the following is NOT required for a standard PCR reaction?
a) DNA template
b) DNA primers
c) Restriction enzymes ✓
d) Thermostable DNA polymerase (Taq)
24. During which step of PCR are the primers extended by DNA polymerase?
a) Denaturation
b) Annealing
c) Extension ✓
d) Ligation
25. Gel electrophoresis separates DNA fragments based on:
a) Charge and size. ✓
