Chapter 7

25 July 2022
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Tumor suppressor genes function to promote cell division, while proto-oncogenes function to halt cell division. True False
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False
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Traditional cancer therapies target only the cancerous cells; therefore, patients rarely experience side effects of the treatment. True False
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False
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The purpose of cell cycle checkpoints is to ensure that cells divide continuously. True False
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False
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The only risk factor for cancer is the transmission of mutant alleles from parent to offspring. True False
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False
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The goal of The Cancer Genome Atlas project is to catalog and understand the DNA mutations found in all cancers. True False
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True
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Some cancers have high rates of mutation, but most have low rates of mutation. True False
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False
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Several mutations are required for the development of colon cancer. True False
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True
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Mutant BRCA1 and BRCA2 alleles are associated with lower rates of breast and ovarian cancer. True False
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False
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Most individuals who are heterozygous for cancer-related alleles will develop cancer at a young age. True False
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False
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Genetic mutations exist in almost all cancers; however, not all cancers are inherited. True False
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True
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Epigenetic changes, including abnormal DNA methylation patterns and imprinting, are observed in many cancers. True False
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True
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Chromosomal aberrations, such as aneuploidy and translocations, are rarely observed in cancer cells. True False
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False
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About 40% of human cancers are characterized by mutations in the ras proto-oncogene, which results in uncontrolled cell division. True False
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True
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A tumor arises from the continued cell division of a single cancerous cell. True False
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True
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Aberrant DNA methylation can lead to cancer because ________. imprinting is prevented hypomethylation can activate key growth control genes hypermethylation can inactivate DNA repair genes the Philadelphia chromosome is caused by demethylation methylation is not present in normal cells
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hypermethylation can inactivate DNA repair genes
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About ______ of all cancers are the result of viral infections. 5% 15% 25% 35% 50%
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15%
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All cancers are caused by mutations. True False
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True
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All cancers have ________. genomic stability higher rates of mutation than normal cells normal chromosomal structures mutant oncogenes normal numbers of chromosomes
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higher rates of mutation than normal cells
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Both BRCA1 and BRCA2 are DNA repair genes. True False
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True
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An individual must have a genetic predisposition for cancer in order for it to develop. True False
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False
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By sequencing the genomes of cancer cells, researchers learned that cancer cells contain ________. more mutations than previously thoughtless mutations than previously thought the same types of mutations in different cancer types translocations, but not missense mutations about the same number of mutations as predicted
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more mutations than previously thoughtless mutations than previously thought
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Cancer therapies such as Gleevec and Herceptin may be preferable to traditional therapies that use radiation and chemicals because these new therapies ________. can treat several different cancer types prevent the inheritance of cancer-causing alleles target all dividing somatic cells target only cancer cells remove excess methylation from DNA repair genes
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target only cancer cells
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Cells can grow uncontrollably and cause a tumor that is not cancerous, but instead is ____________.
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benign
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Cells that acquire the ability to divide uncontrollably, and which can break away and move to other locations in the body, are called _____________.
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malignant
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During mitosis, the attachment of spindle fibers to chromosomes is monitored to enable the anaphase separation of chromosomes. This occurs at which checkpoint? G1/S G2/M M
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M
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Exposure to ________ increases the risk for developing lung cancer, which causes 30% of all cancer deaths in the US. Gardasil cigarettes, but not chewing tobacco the human papilloma virus UV radiation all tobacco products
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all tobacco products
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For colon/rectal cells to become cancerous, _______ mutation(s) must occur in the cells. 1 2 3-4 5+
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5+
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Herceptin, a drug for treating breast cancer, competes for the HER2 receptors on the surface of breast cancer cells, blocking them from receiving growth signals and passing them to the cell's nucleus. True False
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True
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If genetic testing reveals the presence of a breast cancer allele in Anna's mother, but not her maternal aunts, then Anna ________. did not inherit this allele from her mother may have inherited this allele from her mother should not be tested for these breast cancer alleles will develop breast cancer at a young age should not seek genetic counseling
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may have inherited this allele from her mother
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Men who inherit the mutant BRCA1 or BRCA2 allele are also at risk of developing breast cancer. True False
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True
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Genes that encode proteins that help regulate the cell cycle by starting and continuing cell division are known as _____________.
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proto-oncogenes
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Genes that initiate or maintain uncontrolled cell growth are known as ______________.
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oncogenes
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Genes that encode proteins that help regulate the cell cycle by turning of or decreasing the rate of cell division are known as __________________.
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tumor-suppressor genes
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A malignant tumor of the eyes that is most relevant in children is known as__________.
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retinoblastoma
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Most cancers are age related since cells only become cancerous after accumulating a specific a number of __________.
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Mutations
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Mutant BRCA1 and BRCA2 alleles ________. increase the risk of breast and ovarian cancer function at the G2/M cell cycle checkpoint are proto-oncogenes decrease the risk of breast and ovarian cancer increase the number of chromosomes in the cell
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increase the risk of breast and ovarian cancer
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Mutations in DNA repair genes do not in themselves cause cancer, but they do increase the ________ across the genome.
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Mutation Rate
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Research has shown that viral genes can promote and sustain the growth of cancer in infected cells. True False
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True
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Since Gleevec binds to the same site as the ATP molecule, ATP cannot provide the signal protein needed to continue cell division; therefore, cancer cells stop dividing and die. True False
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True
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The ________ cell cycle checkpoint ensures that DNA replication has occurred accurately. epithelial G2/M G1/S G0 M
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G2/M
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The acquisition of new chromosomal aberrations during uncontrolled cell growth means that cancers continue to exhibit genomic ____________ as they develop.
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instability
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The cell cycle is regulated by _____ [how many?] main checkpoints.
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Three
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The familial adenomatous polyposis trait for colon cancer is associated with __________ instability.
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Chromosomal
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The hereditary nonpolyposis trait for colon cancer is associated with failures in ________.
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DNA Repair
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The protein product of the p53 gene functions at the G1/S cell cycle checkpoint, pausing the cell cycle if DNA damage occurs; therefore, p53 is a(n) ________. tumor suppressor gene signal transduction pathway example of loss of heterozygosity oncogene proto-oncogene
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tumor suppressor gene
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The ras proto-oncogene family encodes proteins that function in ________, relaying signals from outside the cell across the cell membrane. protein folding DNA mutation metastasis tumor suppression signal transduction
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signal transduction
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The specific translocation forming the Philadelphia chromosome leads to chronic myelogenous leukemia because ________, resulting in continuous cell division. the cells become aneuploid the BCR gene sequences "switch off" the ABL1 allele the ABL1 gene sequences "switch on" the BCR sequences the cells become polyploid the BCR gene sequences "switch on" the ABL1 sequences
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the BCR gene sequences "switch on" the ABL1 sequences
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There will always be a baseline rate of cancer because ________. all cancer mutations are inherited pollution causes cancer all cancers are ultimately caused by mutations cancer is contagious most tumors are benign
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all cancers are ultimately caused by mutations
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This checkpoint determines whether cells will enter the S phase or will be sent to the G0 (G-zero) non-dividing state. G1/S G2/M M
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G1/S
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This checkpoint makes sure that the DNA has been replicated and that any damage to the DNA has been repaired. G1/S G2/M M
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G2/M
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Unrepaired DNA breaks decrease the rate of cancer causing mutations in genes located at or near break points. True False
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False
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When an individual is heterozygous for a cancer-related allele, s/he may develop cancer after mutation of the other, normal allele, a concept known as ________. metastasis accumulation of mutations with age loss of heterozygosity chromosomal mutations cell division
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loss of heterozygosity
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When cells detach from a tumor and move to other locations in the body they are said to have _______________.
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metastasis
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When six or more mutations in the FAP gene occur in a specific sequence in a certain cell, the result is ________. polyp intermediate adenoma colon cancer normal epithelium late adenoma
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colon cancer
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Women carrying one mutant BRCA1 or BRCA2 allele do not have an increased risk of developing ovarian cancer. True False
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False
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________ occur(s) when cancer cells migrate away from the primary tumor and form new malignant tumors in other parts of the body. Malignancy Metastasis Mutations Cell division Cloning
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Metastasis
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A(n) ___________ between chromosome 9 and chromosome 22 in chronic myelogenous leukemia results in a Philadelphia chromosome.
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translocation
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A cellular molecular pathway by which an external signal is converted into a functional response is called ______.
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signal transduction
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The field of epigenetics has opened the way for the development of a new class of anticancer drugs ____. that increase the level of methylation in cancer cells that stop mutations before they occur in individuals with a predisposition to certain kinds of cancer because of the discovery that epigenetic modification of key genes is important in some cancers and the fact that epigenetic changes are reversible used specifically to treat breast cancer because the key genes involved in this cancer cannot be epigenetically modified that are very similar to many chemotherapy treatments but are much more targeted and effective
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because of the discovery that epigenetic modification of key genes is important in some cancers and the fact that epigenetic changes are reversible
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If a cell begins to divide in an uncontrolled way, it ____. may form a benign tumor signals uncontrolled cell division in other parts of the body is a sign of metastasis will always form a cancerous tumor is considered a malignant tumor
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may form a benign tumor
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Formation of __________ is an intermediate stage in the development of colon cancer.
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polyps
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Cancer-causing mutations of the cell cycle ____. increase the speed of the cycle interfere with S phase of the cycle stop the cycle and cause a build-up of cell toxins cause the cell to bypass checkpoints in the cycle eliminate one or more stages of the cycle
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cause the cell to bypass checkpoints in the cycle
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The RB1 tumor-suppressor gene ____. controls the G1/S checkpoint is overactive in cases of retinoblastoma is overactive in cases of breast cancer is overactive in cases of leukemia controls the G2/M checkpoint
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controls the G1/S checkpoint
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A characteristic of all cancers is that ____. they are always due to a chromosome disjunction mutation several mutations in several different genes are required in order for cancer to develop the cells divide continuously they have a benign form and a deadly form the rapid proliferation of cells is required
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the cells divide continuously
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Abnormal epigenetic patterns of DNA ___________ are associated with many types of cancer, and the removal of these epigenetic markers can activate genes involved with cell growth and increase genomic instability.
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methylation
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During metabolism, cancer-causing ____ are generated. reactive oxygen species (ROS) BCR-ABL proteins mutated tRNA fragments methyl amines BRCA1 genes
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reactive oxygen species (ROS)
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During the M checkpoint, the cell ____. proceeds to G2 phase and the cell prepares to divide proceeds to S phase or enters inactive G0 state proceeds to interphase and completes DNA replication monitors attachment of spindle fibers to chromosomes monitors completion of DNA synthesis and DNA damage
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monitors attachment of spindle fibers to chromosomes
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Stem cells ____. are the least likely to give rise to cancer are found only in cancerous tumors do not have the ability to divide have the property of self-renewal by division are immature cells that become nerve tissue susceptible to cancer
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have the property of self-renewal by division
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One of the properties of cancer is its ability to spread, or __________, to other sites in the body.
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metastasize
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In rapidly dividing cells, expression of BRCA1 and BRCA2 genes is the highest during the ____. mitosis to cytokinesis transition G1/S transition and into S phase G2/mitosis transition metaphase to anaphase transition S/G2 transition
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G1/S transition and into S phase
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According to the American Cancer Society, 30% of all cancer deaths in the U.S. are due to ____. ultraviolet light exposure smoking industrial pollutants pesticide and herbicide exposure automobile exhaust
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smoking
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Many specialized cells, such as white blood cells, ____. remain in G0 until stimulated by external signals to reenter the cell cycle and divide divide continuously and never transition to G0 remain in S until hormonal signals cause the cell to reenter the cell cycle and divide mutate into other cell types by signals from bone marrow cells skip anaphase in order to avoid the high likelihood of mutation during this phase of mitosis
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remain in G0 until stimulated by external signals to reenter the cell cycle and divide
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Genes that turn off or decrease the rate of cell division are known as ________genes.
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tumor suppressor
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In most cases, cancer-causing mutations ____. occur during the G0 phase of the cell cycle accumulate over a number of years must all occur on the q arm of a chromosome metastasize within a short time accumulate very quickly within a single cell
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accumulate over a number of years
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A proto-oncogene ____. causes cancer regulates cell division encodes tumor-suppressing proteins always becomes cancerous repairs DNA
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regulates cell division
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About ____ of all cancer cases have a hereditary component. 10% to 15% 5% to 10% 1% to 3% 25% to 35% 15% to 20%
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5% to 10%