CH 12 BIO – Flashcard

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Proto-oncogenes function by preventing cells from dividing uncontrollably.
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False
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A woman inherits a mutant BRCA1 allele from her mother. She has an increased risk of developing breast cancer because
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a mutation in her normal BRCA1 allele may lead to cancer, whereas a normal individual would have to acquire two mutations (one in each allele) to develop cancer.
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In the absence of lactose,
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the repressor binds to the operator, and the genes of the lac operon are not transcribed.
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Prokaryotes regulate gene expression with a promoter.
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True
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Which of the DNA sequences shown in the figure is/are bound by a regulatory protein?
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3
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A protein that promotes apoptosis would be considered a(n)
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tumor suppressor.
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Stem cells that contain telomerase can be found in adults.
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true
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Lactose ______ the repressor, causing it to ______.
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inactivates; fail to bind to the operator
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In eukaryotes, one gene may specify the construction of several proteins.
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True
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A(n) ___ is to reproductive cloning as a(n) ___ is to therapeutic cloning.
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clone; specialized cell
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Signal transduction pathways can stimulate transcription activators.
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true
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Transcription of the genes of the lac operon is ______ unless _______ is _______.
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off; lactose; present
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A positive genetic test for telomerase indicates that
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a cell is probably cancerous.
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If tumor cells have a faulty, non-functional proteinase, they will be unable to undergo which of the following processes?
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metastasis
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Embryonic cells and cancer cells are similar because
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telomerase is active.
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Prokaryotes cannot regulate gene expression at which of the following levels?
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alternative mRNA processing and chromatin compaction
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Cells from the root of a carrot may be used to generate an entire carrot plant. This illustrates that
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every cell of the root contains all of the plant's genes.
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Many growth factors are classified as which of the following?
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oncogenes
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The unpacking of heterochromatin into euchromatin does not immediately result in DNA transcription because
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histones still block the binding of RNA polymerase to the promoter.
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Heterochromatin differs from euchromatin in that heterochromatin
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is transcriptionally inactive.
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In prokaryotes, an operon includes
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a cluster of genes and the DNA sequences that control their transcription.
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Which of the following is not a characteristic of cancer cells?
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exhibit contact inhibition
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What would be the most likely result on the regulation of the lac operon from a non-functional repressor protein?
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transcription of the lactose metabolizing genes, even when lactose is absent
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Cancer will occur if one copy of a mutant tumor suppressor gene is inherited.
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false
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Specialized cells differ from one another because
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they only express certain genes.
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Histone displacement is necessary for transcription to occur in euchromatin.
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true
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In the absence of growth factors, the retinoblastoma (RB) protein binds a transcription activator called E2F, preventing the cell from entering S stage. A mutation in E2F occurs that causes RB to no longer bind it. This mutant E2F would be considered a(n) ________.
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oncogene
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In order to clone adult animals, scientists typically begin with
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an enucleated egg.
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A point mutation in the operator of the lac operon would most likely cause
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no binding of the repressor protein to the operator even when lactose is absent.
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Which of the following reasons explains a possible advantage of using adult stem cells in therapeutic cloning rather than embryonic stem cells?
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Adult stem cells may be obtained from the patient and would be less likely to be rejected by the patient's body.
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Angiogenesis contributes to carcinogenesis because
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it causes blood vessels to grow into the tumor.
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Proteins are active immediately after translation occurs.
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false
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Inheritance of mutant forms of some genes may lead to a predisposition to develop cancer. Which of the genes listed below has not been linked to hereditary forms of cancer?
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DScam
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Which of the following series of events is in the correct order?
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no chemical binds to receptor, signal transduction pathway stimulates target gene, target gene stimulates transcription activator no signal transduction pathway stimulates receptor, transcription activator is activated by target gene no signal transduction pathway activates receptor, chemical binds to receptor, target gene stimulates transcription activator Signal transduction pathways are initiated by the binding of a chemical signal by a receptor, which initiates the pathway. The pathway usually ends with the stimulation of a transcription activator, which brings about the needed response in the cell by causing the transcription of needed genes.
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If the maternal X chromosome is inactive and seen as Barr body in one cell, then it is the maternal X chromosome that is inactive and seen as a Barr body in every cell of that woman's body.
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false
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Signal transduction pathways can stimulate transcription activators.
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true
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The protein derived from a particular gene is different when it is found in a neuron than in a muscle cell. This is most likely due to
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alternative mRNA processing.
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An oncogene is more likely to lead to cancer than a mutant tumor suppressor because
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a gain of function mutation in an oncogene need only occur in one allele before it disrupts control of the cell cycle.
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Therapeutic cloning
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can produce specialized cells to treat human disease.
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Which of the DNA sequences shown in the figure are transcribed and translated to produce proteins?
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1 and 4
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A proto-oncogene differs from a tumor suppressor gene because a proto-oncogene
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stimulates mitosis in a normal cell, whereas a tumor suppressor gene inhibits mitosis.
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Transcription activators are different from transcription factors in that
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not transcription activators are required for RNA polymerase binding, while transcription factors slow RNA polymerase binding. not transcription activators accelerate transcription, while transcription factors assist RNA polymerase binding. Transcription factors are proteins that are required for RNA polymerase to bind to a promoter. RNA polymerase can bind a promoter and transcribe a gene when transcription activators are not present, but their presence accelerates the process when they bind DNA and promote transcription.
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A translocation may lead to cancer if it
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disrupts control of expression of genes that regulate the cell cycle.
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Which of the following events in gene expression control does not occur in the nucleus?
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mRNA translation
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Female mammals form Barr bodies because
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no compacting the chromatin in one of their X chromosomes allows them to produce more gene product than a male from the other X chromosome. Barr bodies are formed because otherwise, a female would produce twice as much gene product as a male from genes on the X chromosome, and too much of some gene products can be harmful.
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Why is it necessary to "starve" the donor cells prior to reproductive cloning?
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to force the cells into G0 stage so that the nuclei removed from them will respond to cytoplasmic growth signals
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A mutation that causes a gain of function in a tumor suppressor gene would not likely cause cancer because a tumor suppressor protein
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no activates a signal transduction pathway. no normally promotes the cell cycle. A tumor suppressor normally inhibits the cell cycle, and a gain of function mutation would not affect this activity. Cell division would still be repressed, and so cancer (uncontrolled cell division) would be very unlikely to result.
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Why do adult stem cells currently have fewer uses in therapeutic cloning than embryonic stem cells?
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Embryonic stem cells may become any type of cell, whereas adult stem cells may only become a limited number of cell types.
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Cancer cells have abnormal chromosomes because they express telomerase when they should not.
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false
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In the regulation of the lac operon, when lactose is present,
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lactose binds to the repressor, making it unable to bind to the operator and allowing transcription to proceed.
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