3.4.2 DNA and protein synthesis

Question 1

Describe the structure of tRNA.

Answer 1

• tRNA is a single polynucleotide strand that’s folded into a clover shape.
• Hydrogen bonds between specific base pairs hold the molecule in this shape.
• It has a specific sequence of three bases at one end called an anticodon.
• They have an amino acid binding site at the other end.

Question 2

Where does transcription take place in eukaryotes?

Answer 2

Transcription takes place in the nucleus.

Question 3

A drug that inhibits cell growth is found to be able to bind to DNA, preventing RNA polymerase from binding. Explain how this drug will affect protein synthesis.
[2 marks]

Answer 3

• The drug binds to DNA, preventing RNA polymerase from binding, so transcription can’t take place and no mRNA can be made.
• This means there’s no mRNA for translation and so protein synthesis is inhibited.