1. Your roommate purchased a “direct-to-consumer” genetic test and now wants you
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Question
1. Your roommate purchased a “direct-to-consumer” genetic test and now wants your help understanding the results. (These genetic tests analyze DNA in consumer’s saliva to determine their genotypes for certain diseases. The consumer then receives a printout of the results.)
A. Your roommate’s results are positive for a loss-of-function mutation in the retinoblastoma gene, which acts as a tumor suppressor. Only one copy of this gene is mutated. Explain to your roommate why this mutation increases his/her chances of developing cancer.
Explanation / Answer
1. A los of function mutation results in a protein that loses its activity. The altered gene product that results from the mutation does not have the molecular function of the wild-type gene.
Retinoblastoma gene codes for retinoblastoma protein which is a tumor suppressor protein. It regulates the cell cycle progression, it maintains the cells in G1 phase till they receive stimulation to proceed into S phase. When mitotic signals are received by the cells, the retinoblastoma protein gets phosphorylated. Phosphorylation leads to inactivation of the protein, the cell cycle progress further.
Inactivation of this protein may lead to development of cancer cells. A cancer is a mass of cells which lost regulation over cell cycle.
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