Question 1

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

Accepted Answer

DNA → RNA → Protein

Question 2

During transcription in eukaryotic cells, which of the following modifications occurs to the pre-mRNA before it leaves the nucleus?

Accepted Answer

Addition of a 5' cap and a poly-A tail, and removal of introns

Question 3

If a DNA template strand has the sequence 3'-TACGGTACC-5', what is the corresponding mRNA sequence produced during transcription?

Accepted Answer

$$5'	ext{AUGCCAUGG}3'$$

Question 4

Which of the following statements about the genetic code is FALSE?

Accepted Answer

It is ambiguous, meaning one codon can code for more than one amino acid.

Question 5

A mutation changes the DNA sequence from 3'-CTT-5' to 3'-CAT-5' in the hemoglobin gene. What is the effect on the protein, and what disease can result?

Accepted Answer

The amino acid changes from glutamic acid to valine, causing sickle cell anemia.

Question 6

Which of the following best explains why antibiotics like tetracycline can kill bacteria but not harm human cells?

Accepted Answer

They target the 70S ribosomes found only in prokaryotes.

Question 7

A point mutation that does NOT change the amino acid sequence of a protein is called:

Accepted Answer

Silent mutation

Question 8

If an mRNA molecule is 900 nucleotides long (excluding the stop codon), how many amino acids will the resulting polypeptide contain?

Accepted Answer

$$\frac{900}{3} = 300$$

Question 9

Which of the following is NOT a function of tRNA during translation?

Accepted Answer

Forming peptide bonds between amino acids

Question 10

A frameshift mutation is most likely to result from:

Accepted Answer

An insertion or deletion of a single nucleotide

Question 11

Which of the following best describes the role of the promoter in transcription?

Accepted Answer

It is the DNA sequence where RNA polymerase binds to initiate transcription.

Question 12

Which of the following is a difference between DNA and RNA?

Accepted Answer

DNA contains deoxyribose, while RNA contains ribose.

Question 13

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

Accepted Answer

UAG

Question 14

A mutation in a proto-oncogene that causes it to be permanently active can result in:

Accepted Answer

Uncontrolled cell division and possibly cancer

Question 15

Which of the following best explains why a single base-pair insertion in a gene can have a more severe effect than a base-pair substitution?

Accepted Answer

It causes a frameshift, altering the reading frame for all downstream codons.

Question 16

Which of the following is true about alleles?

Accepted Answer

They are different versions of the same gene with slight differences in nucleotide sequence.

Question 17

Which of the following is a real-world example of a disease caused by a point mutation?

Accepted Answer

Sickle cell anemia

Question 18

Which of the following best describes the function of rRNA?

Accepted Answer

It forms part of the structure of ribosomes and helps catalyze protein synthesis.

Question 19

Which of the following is the correct sequence of events during translation?

Accepted Answer

Initiation → Elongation → Termination

Question 20

A mutation changes a codon from UAU (tyrosine) to UAA. What type of mutation is this, and what is the likely effect?

Accepted Answer

Nonsense mutation; translation will stop prematurely

Molecular Biology of the Gene: From DNA to Protein and Mutations

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