Concept explainers
Cell cycle checkpoint (cyclin-CDK complexes) and DNA damage checkpoint (which depend on p53) regulate proper cell division. Inappropriate cell division or loss of normal cellular checks may lead to cancer. Cancer is defined as an uncontrolled growth of abnormal cells. Generally, oncogenes and tumor suppressor genes promote and inhibit the growth of cancer, respectively.
Explanation of Solution
Oncogenes: Oncogenes can cause cancer. They may be mutated or highly expressed in a cell. They can promote uncontrolled cell division, for example, Rous sarcoma virus. The gene of Rous sarcoma virus encodes highly expressive protein kinase, which is similar to signaling protein kinases. This viral gene is called v-src. Oncogenes inhibit the process of apoptosis (a programmed cell death), thereby, they promote survival and continuous proliferation of cancer cells.
Proto-oncogenes: They are normal genes involved in various cellular mechanisms such as cell division and growth. Genetic alteration on the proto-oncogenes due to mutation may lead to the conversion of proto-oncogenes to oncogenes. Nearly most of the proteins involved in the signaling cascade of cell division are products of proto-oncogenes, including growth factors, G-proteins, protein kinases, and cell-surface receptors. Mutation of these genes can result in oncogenes. Proto-oncogenes do not cause cancer directly, however, mutations of proto-oncogenes may induce cancer.
Tumor suppressor genes: Tumor suppressor genes generally inhibit cell division, thereby, they prevent the progression of cancer. They control the uncontrolled cell proliferation, some tumor suppressor genes are involved in checkpoints of the cell cycle, for example, p53. Other tumor suppressor genes can inhibit the expression of genes that induce cell division. These genes act against proto-oncogenes, therefore, cell division depends on the expression of proto-oncogenes or oncogenes and cell-cycle arrest depends on tumor suppressor genes.
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Chapter 11 Solutions
BIOLOGY HOW LIFE WORKS (LL) W/ 2 TERM AC
- Why are oncogenes usually dominant in their action, whereas tumor-suppressor genes are recessive?arrow_forwardIs PI3K a proto-oncogene or a tumor suppressor gene? Why?arrow_forwardWhat is the difference between a proto-oncogene and a tumor suppressor gene? How can mutations in these genes lead to cancer?arrow_forward
- What are proto-oncogenes, oncogenes, and tumor suppressor genes and what is their involvement in cancer?arrow_forwardHow do BRCA1 and BRCA2 function in regard to cell proliferation (are they proto-oncogenes, oncogenes, or tumor suppressor genes)?arrow_forwardIn the pathway below, normal signalling driving cell division requires a mitogen (ligand), an RTK, Ras and proteins X and Y. Which of the following statements is true about the genes that encode the mitogen and Ras in healthy cells? mitogen active Ras protein CYTOSOL GTP active signaling protein Y active receptor active signaling protein X tyrosine kinase CELL DIVISONarrow_forward
- What are Tumor-suppressor genes ?arrow_forwardWhich of the following mutations is MOST likely to cause cancer? A) a mutation that causes a cyclin gene to be expressed at all times during the cell cycle B) a mutation that causes an oncogene to be turned off so that no protein is made C) a mutation that causes a Cdk gene to be turned off so that no protein is made D) a mutation that causes a tumor suppressor gene to be over-expressedarrow_forward1. a)Proteins that stimulate/promote progression through the cell cycle are encoded by (oncogenes or tumor suppressor genes). Boldface one. b)Proteins that inhibit progression through the cell cycle are encoded by (oncogenes or tumor suppressor genes). Boldface one. c)What is the difference between a proto-oncogene and an oncogene? d)To cause cancer, proto-oncogenes require (1 or 2)allele(s) to be mutated and therefore are considered (dominant or recessive). The mutation results in a (loss or gain) of function. For each underlined pair, boldface one. e)To cause cancer, tumor suppressor genes require (1 or 2)allele(s) to be mutated and therefore are considered (dominant or recessive). The mutation results in a (loss or gain) of function. For each underlined pair, boldface one.arrow_forward
- What is a primary function of tumor suppressor genes?arrow_forwardhow do tumor suppressor genes and proto-oncogenes causes cancer?arrow_forwardDistinguish between proto-oncogenes and tumor-suppressor genes. To become cancer promoting, do proto-oncogenes and tumor-suppressor genes undergo gain-of-function or loss-of-function mutations? Classify the following genes as proto-oncogenes or tumor-suppressor genes: p53, ras, BCL-2, JUN, MDM2, and p16.arrow_forward
- Human Heredity: Principles and Issues (MindTap Co...BiologyISBN:9781305251052Author:Michael CummingsPublisher:Cengage Learning