Q: Which of the following is the correct central dogma of molecular biology?

$$\text{DNA} \to \text{RNA} \to \text{Protein}$$

Question 1

Which of the following best describes the relationship between genotype and phenotype in a bacterial cell?

Accepted Answer

Genotype is the DNA sequence, and phenotype is the observable trait influenced by both genotype and environment.

Question 2

A scientist discovers a new prokaryotic organism with a circular DNA molecule, operons, and no membrane-bound organelles. Which of the following best describes its genome organization?

Accepted Answer

Circular double-stranded DNA, operons, and absence of a nucleus.

Question 3

Which of the following is the correct central dogma of molecular biology?

Accepted Answer

$$	ext{DNA} 	o 	ext{RNA} 	o 	ext{Protein}$$

Question 4

During DNA replication, which enzyme is responsible for replacing RNA primers with DNA nucleotides?

Accepted Answer

DNA polymerase I

Question 5

A mutation changes a codon from $$	ext{UAC} ($$tyrosine) to $$	ext{UAA}. $$What type of mutation is this, and what is its likely effect?

Accepted Answer

Nonsense mutation; results in premature stop codon and truncated protein.

Question 6

Which of the following best explains how DNA methylation can regulate gene expression in bacteria?

Accepted Answer

DNA methylation silences gene expression by preventing transcription factor binding.

Question 7

In the lac operon, what happens when lactose is present and glucose is absent?

Accepted Answer

The operon is induced, allowing transcription of genes for lactose metabolism.

Question 8

Which of the following best describes the function of tRNA during translation?

Accepted Answer

tRNA brings specific amino acids to the ribosome according to the mRNA codon sequence.

Question 9

A bacterial cell is exposed to a chemical that causes base substitutions. Which type of mutation is most likely to occur if the base change does not alter the amino acid sequence?

Accepted Answer

Silent mutation

Question 10

Which of the following is a key difference between horizontal and vertical gene transfer in bacteria?

Accepted Answer

Vertical transfer involves transfer of DNA from parent to offspring; horizontal transfer involves transfer between unrelated cells.

Question 11

Which of the following best describes the process of transformation in bacteria, as demonstrated by Griffith's experiment?

Accepted Answer

Uptake of free DNA from the environment, leading to genetic change.

Question 12

A scientist is testing a chemical for mutagenicity using the Ames test. What is the principle behind this test?

Accepted Answer

Detecting mutagens by measuring reversion rates in bacteria.

Question 13

Which of the following is NOT a function of mRNA in eukaryotic cells?

Accepted Answer

Catalyzing peptide bond formation during translation.

Question 14

Which of the following best describes a frameshift mutation?

Accepted Answer

A mutation that inserts or deletes bases, shifting the reading frame and usually resulting in a nonfunctional protein.

Question 15

Which of the following enzymes is responsible for synthesizing RNA during transcription?

Accepted Answer

RNA polymerase

Question 16

A bacterial cell with a mutation in the gene encoding DNA ligase would most likely have difficulty with which process?

Accepted Answer

Joining Okazaki fragments on the lagging strand during DNA replication.

Question 17

Which of the following is a characteristic of plasmids in bacteria?

Accepted Answer

Small, circular DNA molecules independent of the chromosome, often carrying antibiotic resistance genes.

Question 18

Which of the following best describes the process of conjugation in bacteria?

Accepted Answer

Transfer of DNA via a pilus, increasing genetic diversity.

Question 19

Which of the following is a stop codon in the genetic code?

Accepted Answer

$$	ext{UAA}$$

Question 20

Which of the following best describes the function of DNA proofreading and repair mechanisms?

Accepted Answer

They ensure high fidelity of DNA replication by correcting errors.

Genetics and Molecular Biology in Microbiology: Key Concepts and Processes

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