Answer both in details. The drug colchicine was formerly used to treat gout. Now

Question

Answer both in details.

The drug colchicine was formerly used to treat gout. Now, other drugs with a similar function are being considered for the treatment of cancer. What cytoskeletal component do colchicines affect, and why would drugs that target this component be effective at treating cancer?       (5 marks)

Tetracycline is an effective antibiotic because it inhibits protein synthesis. The action mechanism is binding the 30s ribosomal subunit in bacteria, thereby preventing the docking of amino-acylated tRNA. With your knowledge of the translation process, explain how tetracycline would prevent protein synthesis. (5 marks)

Explanation / Answer

ANSWER 1

Colchicine is a mitotic inhibitor. It prevents polymerisation of microtubules. Colchicine binds to tubulin which are monomers of microtubules. Colchicine binding to tubulin prevents their polymerisation and formation of microtubules doesnot occur.

Microtubules forms the spindle fibre, which are required to separate chromatids in anaphase.

Therefore colchicine treatment ultimately inhibits the separation of chromatids, thus preventing the cell division.

In case of cancer, cell divides abnormally and they continually keeps dividing. Colchicine is a good inhibitor of cell division, therefore can be used in treatment of cancer.

ANSWER 2

Tetracycline is an inhibitor of translation. Tetracycline has an affinity towards the A site of 30S ribosomal unit which is specialised for recieving the new tRNA having amino acid. Tetracycline binding to A site prevents the addition of new amino acid in the growing polypeptide thus leading to inhibition of translation.

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