Protein Synthesis

Question 1

How can a change in the DNA sequence of a gene result in the production of a different protein?

Answer 1

Changes in the sequence of the mRNA produced in transcription leads to a different amino acid in the polypeptide sequence which is added by tRNA, during translation, at the ribosome. This changes the shape/function of the protein.

Question 2

Myxopyronin inhibits bacterial RNA polymerase.
Explain why the antibiotic myxopyronin can be used to treat bacterial infections in humans (4)

Answer 2

Myxopyronin destroys bacteria/ prevents them reproducing and doesn’t affect human cells. It prevents RNA polymerase binding to non-coding region of DNA during transcription, preventing protein synthesis in the bacterial cell.

Question 3

mRNA differences to DNA

Answer 3

• shorter than DNA
• only a single strand
• U instead of T

Question 4

Transcription

Answer 4

1) RNA polymerase binds to non-coding region of DNA
2) one strand of DNA acts as a template to to build a complimentary strand of mRNA
3) mRNA leaves the nucleus/ moves to the cytoplasm, through the nuclear membrane and attaches to the ribosome

Question 5

Translation

Answer 5

4) coding by codons in the mRNA is for specific amino acids
5) amino acids transfer to the ribosome by tRNA
6) amino acids detach from ribosome and link to form polypeptides
7) different sequences of amino acids within a polypeptide fold into different shapes, forming different proteins