Question 1

In the image of the deer, the albino deer lacks pigmentation. Which molecular event best explains this phenotype?

Accepted Answer

A mutation in the gene coding for the pigment-synthesizing enzyme results in a nonfunctional protein.

Question 2

According to the Central Dogma of molecular biology, which direction does genetic information flow?

Accepted Answer

DNA $$\rightarrow$$ RNA $$\rightarrow$$ Protein

Question 3

Which process occurs in the cytoplasm of eukaryotic cells but not in the nucleus?

Accepted Answer

Translation

Question 4

What is the main structural difference between DNA and RNA?

Accepted Answer

DNA contains deoxyribose, while RNA contains ribose.

Question 5

Why is a triplet genetic code optimal for encoding all 20 amino acids?

Accepted Answer

Because $$4^3 = 64$ possible codons, which is more than enough to code for 20 amino acids.

Question 6

During transcription, which DNA strand is used to synthesize mRNA?

Accepted Answer

The template strand

Question 7

Which codon serves as the start signal for translation in most organisms?

Accepted Answer

AUG

Question 8

What is the effect of a frameshift mutation caused by the insertion of a single nucleotide?

Accepted Answer

It alters the reading frame, potentially changing every amino acid downstream.

Question 9

Which of the following best describes the function of the 5' cap and poly-A tail in eukaryotic mRNA?

Accepted Answer

They protect mRNA from degradation and facilitate export from the nucleus.

Question 10

What is the role of snRNPs and the spliceosome in gene expression?

Accepted Answer

They remove introns from pre-mRNA and join exons together.

Question 11

A mutation changes the codon UGG to UGA in an mRNA sequence. What is the most likely effect?

Accepted Answer

Translation will terminate prematurely, producing a truncated protein.

Question 12

Which enzyme is responsible for matching tRNAs with their correct amino acids?

Accepted Answer

Aminoacyl-tRNA synthetase

Question 13

What is the significance of polyribosomes (polysomes) in protein synthesis?

Accepted Answer

They allow multiple copies of a polypeptide to be synthesized simultaneously from a single mRNA.

Question 14

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

Accepted Answer

It is redundant but not ambiguous; multiple codons can code for the same amino acid, but each codon specifies only one amino acid.

Question 15

Which of the following is NOT a function of ribosomal RNA (rRNA)?

Accepted Answer

Coding for amino acids in proteins

Question 16

Which of the following best describes a missense mutation?

Accepted Answer

A mutation that results in a single amino acid change in the protein.

Question 17

In eukaryotic transcription, what is the function of the TATA box?

Accepted Answer

It helps position RNA polymerase II at the correct start site for transcription.

Question 18

Which of the following is a real-life consequence of a point mutation in the $$eta-$$globin gene?

Accepted Answer

Sickle-cell disease

Question 19

Which of the following statements about exons and introns is correct?

Accepted Answer

Exons are coding regions that remain in mature mRNA, while introns are non-coding regions removed during RNA processing.

Gene Expression: From Gene to Protein (Central Dogma and Molecular Mechanisms)

Study Guide - Practice Questions