Question

Which event may lead to cancer? Select all that apply. A. gene mutation B. functioning p53 protein C.Rb protein phosphorylating D. Improper replication of DNA during synthesis E. faulty DNA repair Mark for Review What's This?

Answer 1

Ans: option a) Gene mutation: Yes gene mutation may lead to cancer, how, as we know that there are some proto-oncogenes present in our genome which are used in cell cycle checkpoint like Cyclins. Mutation in any one of these gene will cause them to change into oncogenes this type of mutation is called as gain of function and due to which they are not able to identify that whether the cell is ready to move into the next phase of the cell cycle or not and this will leads to uncontrolled celll division which ultimately leads to Cancer.

option b) Functioning of p53 protein, No p53 is a true tumour-suppressor gene and because of its huge function in programmed cell death its functioning prevent the cell to undeergo controlled cell division.

option c) Function of Rb is to prevent excessive cell growth by inhibiting cell cycle progression until a cell is ready to divide. When the cell is ready to divide, Rb is phosphorylated to pRb, leading to the inactivation of the activity of Rb. This process allows cells to enter into the cell cycle state. So if because of some fault cell is not ready to divide but Rb still phosphorylates then this will take the cell into the cell cycle state and which may leads to uncontrolled division and ultimately to cancer.

option d) Yes, because this improper replication may result in mutation in the gene segment which leads to the formation of truncated protein and if this protein is involved in cell cyle then because of its faulty nature it may not able to function properly and this may lead to cancer.

option e) Yes,faulty DNA repair leads to mutations or chromosomal aberrations and if its affecting oncogenes and tumor suppressor genes, cells undergo malignant transformation resulting in cancerous growth.