This set of Microbiology Multiple Choice Questions & Answers (MCQs) focuses on “Microbial Metabolism – Transcription and Translation of Genetic Information”.
1. Translation takes place before transcription.
a) True
b) False
View Answer
Explanation: According to the central dogma of molecular genetics, the first step is DNA replication, the second is a transcription and the last step is translation.
2. Which of the following bacteria can synthesize all of the amino acids required for protein synthesis?
a) E.coli
b) Lactobacillus bravis
c) Saccharomyces cerevisiae
d) Bacillus subtilis
View Answer
Explanation: Microorganisms differ widely in their ability to synthesize amino acids like E.coli can synthesize all of the amino acids required for protein synthesis, whereas lactic acid bacteria cannot.
3. RNAase is a single polypeptide chain of __________ amino acid residues.
a) 2
b) 350
c) 4
d) 124
View Answer
Explanation: RNAase is a single polypeptide chain of 124 amino acid residues; it is folded, bent and twisted into a globular shape in its active form.
4. Protein synthesis in bacteria takes place on which of the following organelles?
a) Endoplasmic Reticulum
b) Golgi body
c) Ribosomes
d) Mitochondria
View Answer
Explanation: Protein synthesis in bacteria takes place on the ribosomes, which are larger RNA-protein particles in the cytoplasm of the bacterial cell.
5. Which of the following RNA constitutes 90 percent of the total cellular RNA?
a) rRNA
b) tRNA
c) mRNA
d) hnRNA
View Answer
Explanation: Ribosomal RNA (rRNA) constitutes about 90 percent of the total cellular RNA and this is important from all other types of RNA.
6. The synthesis of polynucleotide chain of mRNA is catalyzed by the enzyme _____________
a) RNA helicase
b) RNA polymerase
c) DNA polymerase
d) DNA helicase
View Answer
Explanation: The synthesis of polynucleotide chain of mRNA is catalyzed by the enzyme RNA polymerase. The process in which a single-stranded mRNA is synthesized complementary to one DNA strand is called transcription.
7. Which of the following is responsible for the initiation of RNA polymerase activity?
a) initiation site
b) promoter region
c) sigma factor
d) rho factor
View Answer
Explanation: In bacteria, the initiation of RNA polymerase activity at the initiation site is due to an initiation factor called the sigma factor, which is a component of the enzyme.
8. Rho factor is a dimeric protein factor.
a) True
b) False
View Answer
Explanation: Rho factor is a tetrameric protein factor that binds to RNA polymerase and promotes its termination. When transcription has been completed, rho dissociates from the RNA polymerase-DNA complex.
9. The following code codes for which of the amino acid respectively?
AUG and GUG
a) Phenylalanine, tyrosine
b) Methionine, valine
c) Methionine, alanine
d) Lysine, valine
View Answer
Explanation: Three base triplets form a codon that codes for an amino acid. Thus AUG codes for methionine and GUG codes for Valine. AUG and GUG are both initiating codons for translation.
10. Which of the following are non-sense codons?
a) AUG
b) GUG
c) UAA
d) UCU
View Answer
Explanation: UAA, UAG and UGA are polypeptide-chain-terminating codons and are called non-sense codons.
Sanfoundry Global Education & Learning Series – Microbiology.
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