Ch 14

Question 1

Degenerate Genetic Code

Answer 1

Multiple codons code for the same amino acid.

Question 2

Wobble Effec

Answer 2

Flexibility in the third base of a codon allows for this degeneracy, providing a buffer against mutations.

Question 3

What are the functions of the 5’ cap and poly-A tail on the mRNA strands?

Answer 3

5’ Cap: Protects mRNA from degradation, assists in ribosome binding for translation.

Poly-A Tail: Enhances mRNA stability, aids in nuclear export, and assists in translation
initiation.

Question 4

For both prokaryotes and eukaryotes, what are the three stages of transcription? What
occurs in each stage?

Answer 4

1. Initiation
   • RNA polymerase binds to the promoter region of the gene.
   • The DNA double helix unwinds, and the enzyme starts RNA synthesis.
2. Elongation
   • RNA polymerase reads the DNA template strand and synthesizes the
   corresponding RNA strand.
   • As the RNA polymerase moves along the DNA, the RNA strand gets longer.
3. Termination
   • Transcription ends when RNA polymerase reaches a termination sequence on the
   DNA.
   • The RNA transcript is released, and the RNA polymerase detaches from the

Question 5

P Site

Answer 5

Holds the tRNA with the growing polypeptide chain

Question 6

A site

Answer 6

Accepts an aminoacyl-tRNA (incoming tRNA with
amino acid)

Question 7

E Site

Answer 7

Exit site for the tRNA after it donates its amino acid

Question 8

What is a promoter? Where on the transcript is it located, upstream or downstream?

Answer 8

A promoter is a DNA sequence that provides a binding site for RNA polymerase and other
transcription factors, thereby initiating the transcription of a specific gene. It is essential for the
regulation of gene expression.

The promoter is located upstream of the gene it regulates.

Question 9

Non-coding regions occur in pre- mRNA. What are these regions called?

Answer 9

Introns

Question 10

What is the name of the enzyme that removes non-coding regions on an mRNA strand?

Answer 10

Spliceosome