Questions (Total word requirement: ~250-350words)1. How does a normal cell become a cancerouscell? What has to happen to it?2. Do mutations that cause cancer in anindividual pass down to the person'soffspring? Explain and give examples.3. The video in the Module 3 Mastering Bio:Cancer Discussion Background focuses on thetelomerase enzyme role in cancerdevelopment. Explain the connection betweentelomerase activity and cancer.4. Which component of cell division machinery isfrequently targeted by anti-cancer drugs? Canyou explain the common side-effects ofchemotherapy (e.g. hair loss, mucositis)based on this information?

Cancer occurs when the cell divides uncontrollably to form a lump called tumor. It may occur due to the exposure of carcinogens which may cause the alteration of the gene expression especially of those genes which may regulate cell division. 1. A normal cell can become a cancerous cell when the mechanism of regulation of cell division fails. In this case, either oncogenes that is cancer causing genes predominate or there occurs mutation in tumor suppression genes. As a result cancet cells continuously divide and redivide. As the time passes, the variations in shapes and sizes of the cancer cells is observed. The nucleus of these cells becomes larger and darker than the normal ones. Abnormal number of chromosomes get arranged in a disorganized manner. Cells lose the boundary or contact inhibition that is they can even spread to neighbouring areas by the process of angiogenesis that is by the growth of new blood vessels. This process is also called metastasis. This occurs in the advanced stages of cancer. 2. Cancer may occur due to the mutations that are the changes in the sequences of DNA that ultimately regulate the cell division process. If these changes occur in the gametes that is sperms or ova then the cancer could be inherited, otherwise those mutations that occur in somatic cells would not be inherited to the offsprings. So it can be said that all the mutations are not heritable and hence all the cancers are not hereditable. In fact, only those mutations that can be passed on to the offspring through the gametes of the parents are inherited and so are the cancers. 3. Telomerase is a sort of reverse transcriptase that synthesizes complimentary DNA with the help of RNA transcript. This enzyme maintain the integrity of the ends of the chromosome called telomeres. That is why cancer cells are characterized by high telomerase activity, which enables these cells to divide indefinitely and uncontrollably. Actually in normal cells telomeres gets shortened everytime the cell divides leading to apoptosis and senescence. Normal cells possess less amount of telomerase activity. 4. Anti cancer therapy drugs usually target the proteins that are responsible for failure of regulation of cell division. In simple words anti cancer drugs target those proteins that help in the regulation of cell division and in Cancer cells which have lost this mechanism. Chemotherapy drugs target fast dividing cancer cells but as these drugs can travel through all parts of the body they may target healthy cells also and jnhibit normal cell division too by controlling the expression of those proteins which regulate cell division. Hence normal cells also stop dividing as a result hair loss, mucositis etc may occur as a side effect of chemotherapy.