This set of Cell Biology Multiple Choice Questions & Answers (MCQs) focuses on “Gene Expression – Transcription”.
1. When was the link between enzymes and inherited disease first elucidated?
Explanation: Archibald Garrod was a Scottish physician who in 1908 reported that the absence of an enzyme led to an inherited disorder Alcaptonuria.
2. Which organism was used for experiments that led to “one gene – one enzyme” hypothesis?
c) Mus musculus
Explanation: In 1940s George Beadle and Edward Tatum of the California Institute of Technology studied Neurospora, a tropical bread mold which led to the proposal of “one gene – one enzyme” hypothesis.
3. Which proteolytic enzyme was used in the experiments aimed at elucidating the mutation that causes sickle cell anemia?
Explanation: In 1956 Vernon Ingram of Cambridge University discovered the molecular consequence of mutation that causes sickle cell anemia. He used the proteolytic enzyme, trypsin, to cleave the hemoglobin.
4. In patients of sickle cell anemia, the hemoglobin contains a substitution for ____________________
a) glutamic acid
b) ascorbic acid
c) carboxylic acid
Explanation: There is valine in sickle cell hemoglobin, in place of glutamic acid in normal cell hemoglobin.
5. What is the intermediate between a gene and its polypeptide?
Explanation: Messenger RNA (mRNA) is the intermediate between a gene and its polypeptide, discovered in 1961. The other types of RNA play diverse roles in a cell.
6. Transcription is the synthesis of ______________________
Explanation: A messenger RNA is a complimentary copy of one of the two strands of DNA that make up a gene. Transcription is the process of synthesis of RNA from a DNA template.
7. After transcribing into RNA, the gene is spliced out of the genome.
Explanation: After transcription of the gene, i.e. production of a messenger RNA from the DNA sequence of the gene, the gene stays in place stored away as genetic information.
8. RNA is a mobile nucleic acid.
Explanation: RNA is a mobile nucleic acid that moves from the nucleus to the cytoplasm after transcription from the gene.
9. Which of the following play a role in structural support?
Explanation: Ribosomal RNA (rRNA) plays a role in structural support and catalyzes the reaction in which amino acids are linked to one another.
10. Which of the following enzymes are used in the process of transcription?
a) DNA polymerases
b) RNA polymerases
c) DNA helicase
d) DNA topoisomerase
Explanation: RNA polymerases or DNA-dependent RNA polymerases are the enzymes responsible for transcription in both eukaryotes and prokaryotes.
11. Promoter is a ____________________
b) site on DNA
c) site on RNA
Explanation: Promoter is sequence on the DNA which is the site of binding for RNA polymerase, prior to initiation of transcription.
12. Which of the two strands of DNA will be transcribed is determined by the _______________
a) RNA polymerase
b) DNA polymerase
c) Promoter sequence
d) Inducer sequence
Explanation: In addition to being a binding site for RNA polymerase, promoter sequences contain the information that determines which of the two strands is transcribed and the site where transcription is initiated.
13. The transcription factors assist the RNA polymerase in locating ________________
a) stop codon
c) active site
Explanation: The RNA polymerases are not capable of recognizing the promoters located on the DNA to be transcribed. Transcription factors assist the RNA polymerase in doing so.
14. Which enzyme makes the transcription, an essentially irreversible process?
Explanation: Reactions leading to the synthesis of nucleic acids must occur under irreversible conditions. These conditions are met during transcription with the aid of enzyme called pyrophosphatase.
15. In bacteria, binding of _________ factor to the RNA polymerase increases its affinity for promoter sites in the DNA.
Explanation: In bacteria, binding of the sigma factor to RNA polymerase enzyme increases the latter’s affinity for promoter sequences in the DNA.
Sanfoundry Global Education & Learning Series – Cell Biology.
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