Answer these questions with a few short sentences, or in dot points. Sometimes d

Question

Answer these questions with a few short sentences, or in dot points. Sometimes diagrams are a good way to answer the question, if so be sure to use labels and explain the diagram. (Generally ,1 mark per fact.)

Viral infections

1. With regard to influenza, what is antigenic shift? What is the mechanism of this, and what are the implications for influenza disease in human populations (6 marks)

2. What is meant by the term antigenic drift? What are the implications of this for influenza disease in human populations? (4 marks)

3. Why is the significance of the production of the heterophile antibodies associated with glandular fever (infectious mononucleosis). Which pathogen is the most common cause? (5 marks)

Explanation / Answer

(1)

a.) lactose is present, glucose is absent: lac operon is turned on; positive regulation

b.) lactose is absent, glucose is present: Lactose is not the preferred carbohydrate source; lac operon is turned off. Negative regulation

c.) both lactose and glucose are present: If lactose and glucose are present, the cell will use all of the glucose; lac operon is turned off

d.) lactose is present, glucose is absent, but there is a mutation to the sequence in the CAP site: The binding of the CAP-cAMP complex to the promoter site is required for transcription of the lac operon. lac operon is turned off

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