Chapter 8: Protein Synthesis Exam Qs

Question 1

Compare DNA replication and transcription by describing the similarities and differences between the two processes. [6]

Answer 1

Similarities: Helicase enzymes unwind and unzip DNA, and polymerase enzymes joins the two strands of DNA together. Free, activated nucleotides hydrogen bond to the template DNA via complementary base pairing.

Differences: Only a small section of DNA unzips during transcription; different helicase enzymes; products are two new daughter strands of DNA in replication, and one mRNA strand in transcription; RNA vs DNA free nucleotides; RNA vs DNA polymerase

Question 2

Outline the processes and organelles involved in the translation of these proteins from RNA. [4]

Answer 2

mRNA is transported out of the nucleus to a ribosome. Translation occurs at the ribosome. tRNA brings specific amino acids.

Question 3

Explain why a mutation in the viral RNA leads to a change in the 3D shape of the protein antigens. [3]

Answer 3

An altered base sequence of viral RNA means altered primary structure of amino acids. The R-groups interact differently, and the tertiary structure, which is the 3D shape, is determined by R-groups.

Question 4

Describe how a nucleotide base sequence in a gene is used to synthesise a polypeptide. [7]

Answer 4

Transcription:
DNA is copied into mRNA. The free, activated nucleotides line up by complementary base pairing to one template DNA strand.

Translation:
mRNA moves to ribosomes and the tRNA molecules bind to mRNA. The anticodons bind to the codons.