Question 1

Which of the following best describes the 'central dogma' of molecular biology?

Accepted Answer

Genetic information flows from DNA to RNA to protein.

Question 2

During transcription in prokaryotes, what is the role of the promoter region?

Accepted Answer

It defines where RNA polymerase starts synthesizing RNA.

Question 3

Which of the following statements about RNA polymerase is correct?

Accepted Answer

RNA polymerase synthesizes RNA in the 5' to 3' direction using the template strand.

Question 4

What is the function of the methionine-initiator tRNA during translation?

Accepted Answer

It is the only tRNA that can initiate translation by binding to the start codon.

Question 5

Translation in eukaryotes begins when the ribosome complex recognizes which feature of the mRNA?

Accepted Answer

The 5' cap

Question 6

What happens when a point mutation changes the start codon (AUG) in a gene's mRNA?

Accepted Answer

Translation begins at the next available AUG, potentially producing a truncated protein.

Question 7

Which of the following best explains why some point mutations are 'silent'?

Accepted Answer

They alter a codon but do not change the encoded amino acid due to the redundancy of the genetic code.

Question 8

Which amino acids will never have a silent mutation in their codons?

Accepted Answer

Methionine and tryptophan

Question 9

A missense mutation occurs in the coding region of a gene. What is the most likely consequence?

Accepted Answer

A different amino acid is incorporated, which may affect protein function.

Question 10

What is the role of release factors during translation termination?

Accepted Answer

They add a water molecule to the peptide, releasing it from the ribosome.

Question 11

If a point mutation occurs in the stop codon of a gene, what is a likely outcome?

Accepted Answer

Translation may continue, resulting in a longer protein.

Question 12

Which of the following best describes the function of the proteasome in cells?

Accepted Answer

It degrades ubiquitinated proteins into peptides.

Question 13

A mutation in the K-Ras GTPase that prevents GTP hydrolysis will most likely result in which of the following?

Accepted Answer

K-Ras is always active, leading to uncontrolled cell growth.

Question 14

Which of the following is a real-world application of engineered (targeted) mutations?

Accepted Answer

Introducing specific changes in DNA to study protein function

Question 15

Lysozyme catalyzes the hydrolysis of polysaccharides by:

Accepted Answer

Lowering the activation energy of the reaction

Question 16

If Glu35 in lysozyme is mutated to Ala35 (E35A), what is the expected effect on enzyme activity?

Accepted Answer

The reaction is slowed or blocked.

Question 17

Which of the following best explains why the reading frame is important during translation?

Accepted Answer

It ensures that the correct amino acids are incorporated into the protein.

Question 18

A protein is found to be misfolded and nonfunctional. Which cellular system is most likely responsible for its degradation?

Accepted Answer

The proteasome-ubiquitin system

Question 19

Which of the following is true about the genetic code?

Accepted Answer

Some amino acids are encoded by multiple codons.

Question 20

A patient is found to have a mutation in the K-Ras gene that results in a constantly active protein. Which type of therapy might be most effective?

Accepted Answer

A drug that enhances GTP hydrolysis by K-Ras

The Central Dogma of Molecular Biology: From DNA to Protein and the Impact of Mutations

Study Guide - Practice Questions