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

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

Question 1

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

Accepted Answer

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

Question 2

A mutation changes a codon from $$	ext{GAG} to$$ $$	ext{GUG} in $$the gene for $$\beta-$$globin. What is the most likely consequence of this mutation?

Accepted Answer

It results in a missense mutation, changing glutamic acid to valine, which can cause sickle-cell disease.

Question 3

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

Accepted Answer

The genetic code is redundant but not ambiguous.

Question 4

During transcription in eukaryotes, what is the role of the TATA box?

Accepted Answer

It is a promoter element crucial for forming the transcription initiation complex.

Question 5

Which of the following modifications occur to eukaryotic pre-mRNA before it leaves the nucleus?

Accepted Answer

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

Question 6

A frameshift mutation is most likely to result from which of the following?

Accepted Answer

An insertion or deletion of nucleotides not in multiples of three

Question 7

What is the function of aminoacyl-tRNA synthetase in translation?

Accepted Answer

It attaches the correct amino acid to its corresponding tRNA.

Question 8

Which of the following best explains why a single gene can code for multiple proteins in eukaryotes?

Accepted Answer

Alternative RNA splicing allows different combinations of exons to be joined.

Question 9

In the process of translation, what is the role of the ribosome's A site?

Accepted Answer

It holds the tRNA carrying the next amino acid to be added to the chain.

Question 10

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

Accepted Answer

A premature stop codon is introduced, leading to a truncated protein.

Question 11

Why is the genetic code described as 'nearly universal'?

Accepted Answer

It is shared by almost all organisms, from bacteria to animals.

Question 12

Which of the following best describes the process of 'wobble' in tRNA?

Accepted Answer

Flexible pairing at the third base of a codon allows some tRNAs to bind to more than one codon.

Question 13

A scientist inserts a jellyfish gene for green fluorescent protein (GFP) into a mouse genome. The mouse expresses GFP and glows green under UV light. What does this experiment demonstrate?

Accepted Answer

The universality of the genetic code allows genes to be expressed across species.

Question 14

Which of the following is NOT a function of the 5' cap and poly-A tail added to eukaryotic mRNA?

Accepted Answer

They code for amino acids in the resulting protein.

Question 15

Which of the following best explains why insertions and deletions are often more harmful than substitutions?

Accepted Answer

They can cause frameshift mutations, altering the entire downstream amino acid sequence.

Question 16

During translation, what event occurs when a stop codon is reached?

Accepted Answer

A release factor binds to the A site, causing the polypeptide to be released.

Question 17

Which of the following is true about the relationship between genotype and phenotype as illustrated by gene expression?

Accepted Answer

Proteins produced by gene expression link genotype to phenotype.

Question 18

A patient has a mutation in the promoter region of a gene. Which of the following is the most likely effect?

Accepted Answer

Transcription of the gene may be reduced or prevented.

Question 19

Which of the following best describes the function of the CRISPR-Cas9 system in gene editing?

Accepted Answer

It introduces targeted cuts in DNA at specific locations.

Question 20

Which of the following is the correct sequence of events in eukaryotic gene expression?

Accepted Answer

Transcription → RNA processing → Translation → Protein folding

Gene Expression: From Gene to Protein – Study Notes

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