Biology 9700 · AS & A Level · Principles of genetic technology

Principles of genetic technology — practice question

When infertile women are being prepared for in-vitro fertilisation (IVF), several ovarian follicles need to be encouraged to grow and mature. This is achieved by giving daily injections of the glycoprotein hormone follicle stimulating hormone (FSH). Each FSH molecule has quaternary structure and is built from two different polypeptide chains, $\alpha$ and $\beta$.
(a)[1]

Explain the meaning of quaternary structure.

(b)[3]

Human FSH may be taken from women’s urine (u-hFSH). A method using monoclonal antibodies is employed to obtain purified u-hFSH. Suggest how monoclonal antibodies can be used to obtain purified u-hFSH from urine.

(c)[1]

Recombinant human FSH (r-hFSH) can be made by adding the genes coding for the $\alpha$ and $\beta$ polypeptide chains of FSH to mammalian ovary cells. Suggest why mammalian cells are needed to produce r-hFSH, rather than bacterial cells.

(d)[3]

In IVF treatment, a second hormone, human chorionic gonadotrophin (hCG), is injected after mature ovarian follicles (Graafian follicles) have developed. Draw a labelled diagram to show the structure of a mature ovarian follicle.

(e(i))[4]

With reference to Table 2.1, compare the effects of treatment with r-hFSH and u-hFSH and suggest explanations for the differences.

(e(ii))[2]

The chance that the results for the mean number of mature follicles per woman occurred by chance is $< 0.002$. Explain what this probability means.

Worked solution & mark scheme

This 14-mark question has a full step-by-step worked solution and mark scheme. One marking point: The hormone has more than one polypeptide chain

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