Biology 9700 · AS & A Level · The immune system

The immune system — practice question

Fig. 6.1 shows a simplified representation of a section through the human immunodeficiency virus (HIV) particle that causes HIV/AIDS. The diagram depicts the virus particle just before it attaches to the cell surface membrane of a T-helper cell at a receptor protein known as CD4. A second protein (coreceptor) called CCR5 is also required for the virus particle to enter and then infect the T-helper cell.
(a)[1]

Identify the structure labelled X in Fig. 6.1.

(b)[3]

Explain how destruction of T-helper cells affects the immune system's ability to resist the harmful effects of a pathogen.

(c)[1]

Research has shown that some people avoided HIV infection despite repeated exposure to the virus. Later findings showed that these people carried a mutation in the gene for the CCR5 coreceptor protein. Suggest how mutation of the gene for the CCR5 coreceptor protein could have protected them from HIV infection.

(d)[3]

The use of monoclonal antibodies against the CCR5 coreceptor protein (anti-CCR5) has been shown to be effective in the treatment of HIV infection. Outline how anti-CCR5 monoclonal antibodies can be produced in the laboratory by means of the hybridoma method.

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