Question 1

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

Accepted Answer

Information flows from DNA to RNA to proteins.

Question 2

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

Accepted Answer

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

Question 3

A mutation changes the DNA sequence from $$	ext{TAC} to$$ $$	ext{TAG}. $$What type of mutation is this, and what is its likely effect on the resulting protein?

Accepted Answer

Nonsense mutation; introduces a premature stop codon

Question 4

Which of the following statements correctly compares DNA and RNA?

Accepted Answer

DNA is usually double-stranded, while RNA is usually single-stranded.

Question 5

What is the function of tRNA during translation?

Accepted Answer

It brings amino acids to the ribosome and matches them to the mRNA codons.

Question 6

Which of the following best describes the triplet code?

Accepted Answer

Three nucleotides in mRNA code for one amino acid.

Question 7

A scientist discovers a mutation that causes an exon to be removed from the mature mRNA. What is the most likely result of this mutation?

Accepted Answer

The protein will lack a segment and may lose function.

Question 8

Which of the following is NOT a step in the process of transcription?

Accepted Answer

Translation

Question 9

In a bacterial cell, transcription and translation can occur simultaneously. Why is this possible?

Accepted Answer

Bacteria lack a nucleus, so ribosomes can access mRNA as it is being transcribed.

Question 10

Which of the following best describes the role of the template strand during transcription?

Accepted Answer

It is the DNA strand that is used by RNA polymerase to synthesize mRNA.

Question 11

A patient has a genetic disorder caused by a single nucleotide insertion in a gene. What type of mutation is this, and what is its likely effect?

Accepted Answer

Frameshift mutation; alters the reading frame and likely produces a nonfunctional protein

Question 12

Which of the following is removed from pre-mRNA during RNA splicing?

Accepted Answer

Introns

Question 13

What is the primary function of a spliceosome?

Accepted Answer

To remove introns from pre-mRNA

Question 14

Which of the following best describes the structure of tRNA?

Accepted Answer

A single-stranded molecule with a cloverleaf shape and an anticodon loop

Question 15

During translation, which of the following events occurs at the A site of the ribosome?

Accepted Answer

A new tRNA carrying an amino acid binds to the mRNA codon.

Question 16

After translation, which of the following processes may be required for a protein to become fully functional?

Accepted Answer

Folding and post-translational modifications

Question 17

Which of the following statements about codons is correct?

Accepted Answer

Each codon specifies a single amino acid or a stop signal.

Question 18

Which of the following best describes the difference between transcription and translation?

Accepted Answer

Transcription synthesizes RNA from DNA, while translation synthesizes protein from RNA.

Question 19

A researcher is studying a gene with the following DNA sequence on the template strand: $$	ext{3'-TACGGTACC-5'}. $$What is the corresponding mRNA sequence?

Accepted Answer

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

Question 20

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

Accepted Answer

Sickle cell anemia caused by a single nucleotide substitution in the hemoglobin gene

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