Q: Which of the following best summarizes the central dogma of molecular biology?

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

Question 1

Which of the following correctly differentiates the nucleotides found in DNA and RNA?

Accepted Answer

DNA contains the sugar deoxyribose, while RNA contains the sugar ribose.

Question 2

Which statement best describes the secondary structure of DNA?

Accepted Answer

It consists of two antiparallel strands forming a double helix stabilized by hydrogen bonds between complementary bases.

Question 3

During DNA replication, what is the main challenge associated with replicating the ends of linear eukaryotic chromosomes?

Accepted Answer

DNA polymerase cannot fully replicate the 3' end of the lagging strand, leading to progressive shortening of chromosomes.

Question 4

What is the role of telomerase in eukaryotic cells?

Accepted Answer

It extends the 3' end of the parental DNA strand, preventing chromosome shortening during replication.

Question 5

A mutation changes a codon from UAU to UAA. What type of mutation is this, and what is its likely effect on the protein?

Accepted Answer

Nonsense mutation; it introduces a premature stop codon, likely resulting in a truncated protein.

Question 6

Which of the following best summarizes the central dogma of molecular biology?

Accepted Answer

$$ 	ext{DNA} ightarrow 	ext{RNA} ightarrow 	ext{Protein} $$

Question 7

Which of the following is a function of the 5' cap added to eukaryotic mRNA?

Accepted Answer

It protects mRNA from degradation and assists in ribosome binding during translation.

Question 8

How does the structure of tRNA enable its function during translation?

Accepted Answer

Its three-dimensional L-shaped structure positions the anticodon to pair with mRNA and the opposite end to attach to an amino acid.

Question 9

Which of the following best describes negative control of the lac operon?

Accepted Answer

A repressor protein binds to the operator, preventing transcription when lactose is absent.

Question 10

Which of the following is a key difference between gene expression in bacteria and eukaryotes?

Accepted Answer

Eukaryotes process pre-mRNA by adding a 5' cap and poly(A) tail, while bacteria do not.

Question 11

A patient is found to have a mutation in the p53 gene. What is the most likely consequence of this mutation?

Accepted Answer

Loss of cell cycle control, increasing the risk of uncontrolled cell division and cancer.

Question 12

Which of the following best explains the role of alternative splicing in gene regulation?

Accepted Answer

It allows a single gene to produce multiple protein variants by including or excluding different exons.

Question 13

Which enzyme is responsible for synthesizing the RNA primer during DNA replication?

Accepted Answer

Primase

Question 14

Which of the following scenarios illustrates a missense mutation?

Accepted Answer

A single nucleotide change results in a codon that codes for a different amino acid.

Question 15

Which of the following best describes the function of enhancers in eukaryotic gene regulation?

Accepted Answer

They are DNA sequences that increase the rate of transcription when bound by specific transcription factors.

Question 16

A researcher observes that a eukaryotic gene is highly expressed only when its chromatin is loosely packed. What is the most likely explanation for this observation?

Accepted Answer

Loosely packed chromatin allows transcription factors and RNA polymerase to access the DNA, promoting gene expression.

Question 17

Which of the following best explains why the structure of DNA is responsible for its function as the genetic material?

Accepted Answer

The complementary base pairing and double helix structure allow for accurate replication and storage of genetic information.

Question 18

Which of the following is a direct result of a frameshift mutation?

Accepted Answer

The reading frame of the gene is altered, potentially changing every amino acid downstream of the mutation.

Question 19

Which of the following best describes the role of ribosomes during translation?

Accepted Answer

They facilitate the pairing of tRNA anticodons with mRNA codons and catalyze peptide bond formation.

Molecular Biology: Nucleic Acids, Gene Expression, and Regulation

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