Question 1

Which statement 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 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 via splicing.

Question 3

A codon is comprised of three nucleotides. How many possible codons exist, and how many code for amino acids?

Accepted Answer

There are $$64$$ possible codons, and $$61$$ code for amino acids.

Question 4

Which of the following best explains the role of tRNA during translation?

Accepted Answer

tRNA carries amino acids to the ribosome and matches its anticodon to the mRNA codon.

Question 5

What is the function of the ribosome in protein synthesis?

Accepted Answer

It facilitates the specific coupling of tRNA anticodons with mRNA codons.

Question 6

Which sequence of events correctly describes the process of transcription in eukaryotes?

Accepted Answer

Initiation at the promoter, elongation of the RNA strand, termination after the terminator sequence.

Question 7

A mutation changes the DNA sequence from $$C T C to$$ $$C A C in $$the $$eta-$$globin gene. What is the consequence at the protein level?

Accepted Answer

Glutamic acid is replaced by valine, resulting in sickle-cell hemoglobin.

Question 8

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

Accepted Answer

$$UAG$$

Question 9

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

Accepted Answer

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

Question 10

Which of the following best describes the role of spliceosomes in eukaryotic cells?

Accepted Answer

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

Question 11

During translation, which site on the ribosome does the incoming aminoacyl-tRNA first bind?

Accepted Answer

A site

Question 12

Which of the following is true about the genetic code?

Accepted Answer

It is redundant, meaning multiple codons can code for the same amino acid.

Question 13

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

Accepted Answer

It attaches the correct amino acid to its corresponding tRNA using ATP.

Question 14

Which modification is added to the 3' end of eukaryotic mRNA after transcription?

Accepted Answer

A poly-A tail consisting of 50–250 adenine nucleotides.

Question 15

Which of the following best explains why introns are important in eukaryotic genes?

Accepted Answer

They allow for alternative splicing, which can produce different protein domains from a single gene.

Question 16

A patient has a mutation that changes a codon from $$UAC ($$tyrosine) to $$UAA. $$What type of mutation is this and what is its likely effect?

Accepted Answer

Nonsense mutation; it introduces a premature stop codon, truncating the protein.

Question 17

Which of the following is the correct order of events in translation?

Accepted Answer

Initiation, elongation, termination

Question 18

If a DNA template strand has the sequence $$3' - T A C G G T A C T - 5'$$, what is the corresponding mRNA sequence produced during transcription?

Accepted Answer

$$5' - A U G C C A U G A - 3'$$

Question 19

Which of the following best describes a silent mutation?

Accepted Answer

A nucleotide change that does not alter the amino acid sequence of the protein.

Gene Expression: From Gene to Protein (Chapter 17 Study Notes)

Study Guide - Practice Questions