Question 1

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

Accepted Answer

DNA is transcribed into RNA, which is then translated into protein.

Question 2

During transcription, which enzyme is responsible for synthesizing the RNA strand from a DNA template?

Accepted Answer

RNA polymerase

Question 3

A mutation changes the codon UAU (which codes for tyrosine) to UAA. What type of mutation is this, and what is its likely effect?

Accepted Answer

Nonsense mutation; introduces a premature stop codon

Question 4

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

Accepted Answer

The genetic code is nearly universal and redundant.

Question 5

In eukaryotic cells, which process removes introns from pre-mRNA?

Accepted Answer

RNA splicing

Question 6

A scientist discovers a mutation that causes a single nucleotide substitution, resulting in a different amino acid in the protein. What is this type of mutation called?

Accepted Answer

Missense mutation

Question 7

Which of the following best explains why a frameshift mutation is often more damaging than a point mutation?

Accepted Answer

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

Question 8

During translation, what is the role of tRNA?

Accepted Answer

To bring amino acids to the ribosome and match them to the mRNA codons

Question 9

Which of the following sequences is the correct order of events in gene expression?

Accepted Answer

Transcription → Translation → Protein folding

Question 10

A gene has the following DNA sequence: 5'-ATG GAA TGA-3'. What is the corresponding mRNA sequence produced during transcription?

Accepted Answer

5'-AUG GAA UGA-3'

Question 11

Which of the following best describes the function of a promoter in transcription?

Accepted Answer

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

Question 12

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

Accepted Answer

Addition of a 5' cap and a poly-A tail

Question 13

A patient has a genetic disorder caused by a mutation that prevents the removal of introns from pre-mRNA. What is the most likely consequence?

Accepted Answer

The resulting protein will contain extra amino acids not normally present.

Question 14

Which of the following statements about ribosomes is correct?

Accepted Answer

Ribosomes catalyze the formation of peptide bonds during translation.

Question 15

If a DNA template strand has the sequence 3'-TAC GGT ACC-5', what is the sequence of the mRNA transcribed from this strand?

Accepted Answer

5'-AUG CCA UGG-3'

Question 16

Which of the following best explains why the genetic code is described as 'redundant' but not 'ambiguous'?

Accepted Answer

Multiple codons can specify the same amino acid, but each codon specifies only one amino acid.

Question 17

A mutation in a gene changes a codon from GAA to GAG, but both codons code for glutamic acid. What type of mutation is this?

Accepted Answer

Silent mutation

Question 18

Which of the following is a function of the poly-A tail added to eukaryotic mRNA?

Accepted Answer

It helps protect the mRNA from degradation.

Question 19

Which of the following best describes the role of aminoacyl-tRNA synthetase in translation?

Accepted Answer

It attaches the correct amino acid to its corresponding tRNA.

Question 20

A researcher introduces a chemical that causes the insertion of a single nucleotide into a gene. What is the most likely effect on the resulting protein?

Accepted Answer

A frameshift mutation will occur, likely producing a nonfunctional protein.

Gene Expression: From Gene to Protein – Detailed Study Notes

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