Cells with one functional copy of a tumor suppressor gene will usually prolifera
ID: 175914 • Letter: C
Question
Cells with one functional copy of a tumor suppressor gene will usually proliferate faster than normal cells. Inactivation of tumor suppressor genes leads to enhanced cell of survival and proliferation. Individuals with only one functional copy of a tumor suppressor gene are more prone to cancer than individuals with two copies of a tumor suppressor gene. Ras is a GTP-binding protein that is often defective in cancer cells. A signal from a growth factor through a receptor tyrosine kinase often stimulates normal cells to divide. When the receptor tyrosine kinase binds the growth factor, Ras is stimulated to bind GTP. Ras in turn activates proteins that promote cell proliferation. A common mutation in cancerous cells causes Ras to behave as though it were bound to GTP all the time. Why is this mutation advantageous to cancerous cells? Your friend decides that the signaling pathway involving the Ras protein is a good target for drug design, because the Ras protein is often defective in cancer cells. Your friend designs a drug that will turn off the receptor tyrosine kinase by preventing it from dimerizing. Do you think that this drug will affect cells that have a defective Ras protein that acts as if it were always bound to GTP? Why or why not? What are the Six Hallmarks of Cancer? Identify the following as either an oncogene (O) or a tumor suppressor gene (TS). Genes that normally function to control cell cycle and repair DNA. Genes that become mutated and increase expression of proteins necessary for cell proliferation. ras RB (retinoblastoma) p53Explanation / Answer
20.2 A)
The mutation in Ras protein enables to behave it as it always bound to GTP. This causes the cells to proliferate without disturbance. Thus, the mutation would be advantageous for cancerous cells because, the mutation promotes growth and development of cancerous cells.
B)
The drug designed to prevent dimerization of receptor tyrosine kinases turnoff the mutated Ras protein that behaves as if it always bind to GTP and then inhibits the cell proliferation. Thereofe, the drug can act as anticancer drug.
20.3)
Cancerous cells exhibit the characteristics or hallmarks like uncontrolled growth, differentiation in to non specialized cells that exhibits no contact inhibition by self division stimulating signals or autocrine stimulation. They may possess abnormal chromosomes due to chromosomal translocations. The mutations in genes contribute to cancer by accelerated mutation rates or breaks in genes. The cancerous cells do not undergo apoptosis.
20.4)
A) Genes normally function to control cell cycle and repair DNA are tumor suppressor genes. A tumor suppressor gene is normal cellular gene that regulates the cell proliferation or DNA repairing proteins which may cause genome instability.
B) Genes that become mutated and increase the expression of proteins necessary for cell proliferation are oncogenes. Protooncogenes are normal cellular genes that promote the cell proliferation. A dominant mutation such as gain of function mutation in wild type protooncogene may transform it into an oncogene that causes cancer.
C) ras genes are protooncoge and mutation in ras gene may convert it into oncogene.
D) RB (Retinoblastoma) gene is a tumor suppressor gene that is mutated to proliferate the cancer.
E) p53 is also a tumor suppressor gene involved in producing lung, colon and breast cancers.
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.