Question 1

Write a short account of THREE of the following topics:-

Your short account should include descriptive and explanatory text with annotated diagrams as appropriate. You should expect to write about a side of A4 for each answer. Each topic carries equal marks.

The experiments of Meselsohn and Stahl with E. coli on DNA replication.
Restriction endonucleases and the analysis of the results of a restriction enzyme digest.

Activity at the prokaryotic replication fork.
The structure of DNA.
The experiments of Beadle and Tatum with Neurospora crassa on the link between gene and product.
Translation.

The experiments of Hammerling and Brachet with Acetabularia species on the location of the genetic material in eukaryotes.

Question 2
In prokaryotes, transcription begins at specific points in the genome known as promoters.
a) Using a series of annotated diagrams show what happens at the start of this process. (40 %)
b) Using annotated diagrams show the elongation phase of transcription. (20 %)
c) In prokaryotes there areset termination signals for transcription. Using annotated diagrams show the two different mechanisms used.