Chapter 11/8 MasterBiology – Flashcards
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A benign and a malignant tumor differ in that _____.
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cells of a benign tumor remain within the tumor, whereas cells of a malignant tumor can spread to other body tissues
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A benign tumor differs from a malignant tumor in that a benign tumor
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does not metastasize
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_____ is a carcinogen that promotes colon cancer.
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fat
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The term "gene expression" refers to the
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process by which genetic information flows from genes to proteins.
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Cells become specialized by a process known as _____.
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differentiation
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Anhydrotic dysplasia is a genetic disorder in humans that results in the absence of sweat glands in the skin. Some men have this defect all over their bodies, but in women it is usually expressed in a peculiar way. Women with this disorder typically have small patches of skin with sweat glands and other patches without sweat glands. This pattern of sweat-gland distribution can be explained by _____.
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X chromosome inactivation
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Histones are _____.
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proteins around which DNA is coiled
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In female mammals, the inactive X chromosome in each cell
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becomes a Barr body.
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In eukaryotes, gene expression is regulated mostly by _____.
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controlling the transcription of genes
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Alternative RNA splicing has revealed inaccuracies in the one gene:one polypeptide hypothesis. Why?
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Transcription of the same gene can lead to the production of different mRNAs and therefore different proteins.
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MicroRNA (miRNA) functions by binding to _____ and blocking translation.
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complementary mRNA sequences
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After translation is complete, the insulin polypeptide is activated by _____.
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the cutting of the initial translation product to yield two shorter chains joined together by sulfur linkages
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Gene expression can also be controlled after the mRNA molecule has left the nucleus. These mechanisms may include the _____.
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breakdown of RNA
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All of the following mechanisms are used to regulate protein production except
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DNA replication.
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DNA microarrays are useful tools for studying _____.
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gene expression
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Why can some plants be cloned from a single cell?
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Plant cells can dedifferentiate and give rise to all of the specialized cells required to produce an entire plant.
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Since the first animal was produced using a fully differentiated cell, a number of observations have been made. Which of the following statements is true in regard to reproductive cloning?
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Cloned animals often develop chronic conditions that are usually only associated with old age.
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Which of the following possible uses of reproductive cloning is still considered by most to be an unresolved ethical issue?
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the reproductive cloning of humans
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Why do you think that adult stem cells are found in bone marrow and the lining of the small intestine specifically?
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These cells must be able to regenerate various types of cells throughout life.
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Embryonic stem cells differ from adult stem cells because they _____.
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can differentiate into all cell types
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Proto-oncogenes have the potential to become oncogenes. Which of the following is most likely to lead to cancer?
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a mutation that causes the proto-oncogene to become overactive
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A proto-oncogene is a normal gene that can change into an oncogene. Oncogenes are potentially lethal genes that can cause cancer. Why do cells continue to maintain proto-oncogenes?
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Proto-oncogenes are necessary for normal control of cell division.
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Which of the following would be most likely to lead to cancer?
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generation of multiple copies of a proto-oncogene and inactivation of a tumor-suppressor gene
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Most human cancers are _____.
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caused by the accumulation of mutations
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Melanoma (skin cancer) can develop after several mutations occur in skin cells. If a woman is diagnosed with melanoma and becomes pregnant, what are the chances that her offspring will inherit melanoma?
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It is unlikely that the offspring will be born with melanoma.
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The p53 protein normally _____.
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initiates transcription
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Mutations in the proto-oncogene ras and the tumor suppressor gene p53
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disrupt normal regulation of the cell cycle.
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Exposure to which of the following substances increases cancer risk?
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ultraviolet light exposure
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In humans, the agent responsible for the greatest number of cancers is _____.
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tobacco
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Which of the following statements regarding cancer risk factors is false?
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Mutagens are usually not carcinogens.
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_____ bind(s) to DNA enhancer regions.
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Activators
