(4) Chapter 17

Question 1

What is transcription?

Answer 1

Transcription is the first step in gene expression, where an RNA copy of a gene is made from a DNA template.

Question 2

What are the key stages of transcription?

Answer 2

The key stages of transcription are initiation, elongation, and termination.

Question 3

What happens during initiation of transcription?

Answer 3

RNA polymerase binds to a specific region of DNA known as the promoter.

Question 4

What occurs during elongation in transcription?

Answer 4

RNA polymerase moves along the DNA, synthesizing a complementary strand of RNA.

Question 5

What is termination in transcription?

Answer 5

RNA polymerase reaches a termination signal, releasing the newly synthesized RNA molecule.

Question 6

How does transcription differ in prokaryotic cells?

Answer 6

In prokaryotes, transcription occurs in the cytoplasm, with minimal RNA processing.

Question 7

How does transcription differ in eukaryotic cells?

Answer 7

In eukaryotes, transcription occurs in the nucleus and involves extensive RNA processing.

Question 8

What is a promoter?

Answer 8

The promoter is a DNA sequence located upstream of the gene that serves as the binding site for RNA polymerase.

Question 9

What is the function of RNA polymerase?

Answer 9

RNA polymerase catalyzes the synthesis of RNA from a DNA template.

Question 10

What modifications occur to pre-mRNA in eukaryotes?

Answer 10

Pre-mRNA undergoes the addition of a 5’ cap, a 3’ poly-A tail, and splicing to remove introns.

Question 11

What is the function of the 5’ cap?

Answer 11

The 5’ cap protects the RNA from degradation and helps ribosomes recognize the mRNA for translation.

Question 12

What is the function of the 3’ poly-A tail?

Answer 12

The poly-A tail protects the mRNA from degradation and facilitates export from the nucleus.

Question 13

What is splicing in RNA processing?

Answer 13

Splicing is the process of removing introns and joining exons together.

Question 14

What is the role of the spliceosome?

Answer 14

The spliceosome is a complex that catalyzes the removal of introns from pre-mRNA.

Question 15

What is translation?

Answer 15

Translation is the process by which an mRNA sequence is decoded to build a protein.

Question 16

What are the main components involved in translation?

Answer 16

The main components are mRNA, ribosomes, and tRNA.

Question 17

What is the start codon in mRNA?

Answer 17

The start codon is typically AUG, which codes for methionine.

Question 18

What is the structure of tRNA?

Answer 18

tRNA has a cloverleaf shape with an anticodon loop at one end and an amino acid binding site at the other.

Question 19

When does translation end?

Answer 19

Translation ends when a stop codon (UAA, UAG, or UGA) is encountered in the mRNA.

Question 20

What are point mutations?

Answer 20

Point mutations are changes in a single nucleotide in the DNA sequence.

Question 21

What is a silent mutation?

Answer 21

A silent mutation is a change in one nucleotide that does not affect the amino acid sequence.

Question 22

What is a missense mutation?

Answer 22

A missense mutation results in the substitution of one amino acid for another in the protein.

Question 23

What is a nonsense mutation?

Answer 23

A nonsense mutation creates a premature stop codon, resulting in a truncated protein.

Question 24

What is a frameshift mutation?

Answer 24

A frameshift mutation is caused by insertions or deletions that alter the reading frame of the codons.

Question 25

What are the effects of mutations on protein function?

Answer 25

Mutations can lead to nonfunctional proteins, altered function, or truncated proteins.