Ka3 Gene Expression

Question 1

Structure of mRNA

Answer 1

• single helix
• adenine is uracil
•ribose sugar

Question 2

Describe the role of mRNA

Answer 2

Takes a copy of DNA from the nucleus to the ribosome

Question 3

Role of tRNA

Answer 3

Transfer RNA- carry an amino acid of them

Question 4

Describe the process of transcription

Answer 4

-RNA polymerase moves along the DNA, unwinding double helix, breaking the hydrogen bonds
-free RNA nucleotides are attracted to exposed bases and complementary base pairing takes place.
- when mRNA is completed, breaks away from the DNA, which is then known as the primary mRNA transcript
- Then RNA splicing takes place to make a mature mRNA transcript.

Question 5

Introns

Answer 5

A non coding region of dna

Question 6

Exon

Answer 6

A coding region of dna

Question 7

What happens during rna splicing

Answer 7

Introns are removed and exons are spliced together

Question 8

Process of translation

Answer 8

• The ribosome binds to the 5’ end of the mRNA, begins with the start codon
• A tRNA molecule carrying an amino acid arrives at the ribosome, and is aligned to the codon on the mRNA, using complimentary base pairing with its anticodon
  -A peptide bond forms between the first two amino acids to produce a polypeptide chain.
• repeated until a stop codon is reached at the polypeptide chain is reached and released from the ribosome

Question 9

Where are codons found

Answer 9

mRNA

Question 10

Where are anticodons found

Answer 10

tRNA

Question 11

Name the bond which holds amino acids together in a protein

Answer 11

Peptide bonds

Question 12

What is alternative splicing

Answer 12

Removal of introns and splicing together of exons
Exons are spliced in a different combination resulting in a different protein