,Chapter 1: Cellular Biology
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MULTIPLE CHOICE ;|
1. Whichstatement best describes the cellular function of metabolic absorption?
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a. Cells can produce proteins. c. Cells can take in and use nutrients.
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b. Cells can secrete digestive enzymes. d. Cells can synthesize fats. ;| ;| ;| ;| ;| ;| ;| ;|
ANS: C ;|
In metabolic absorption, all cells takeinand use nutrients and other substances fromtheir
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surroundings. The remaining options are not inclusive in their descriptions of cellular
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metabolic absorption.
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2. Most ofacell’s genetic information, including RNAand DNA, is contained in the:
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a. Mitochondria c. Nucleolus
b. Ribosome d. Lysosome ; | ; |
ANS: C ;|
The nucleus contains the nucleolus, a small dense structure composed largely of RNA,
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most of the cellular DNA, and the DNA-binding proteins, such as the histones, which
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regulateits activity. The other options do not contain most ofacell’s genetic information.
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3. WhichcomponentofthecellprodNuUceRsSIhNyGd Tr oBg.CenO M
;| peroxide (H2O2)byusingoxygento ;| ;| ;| ;| ;| ;| ;| ;| ;| ;| ;| ;| ; | ;| ;| ;| ;|
remove hydrogen atoms from specific substrates in an oxidative reaction?
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a. Lysosomes c. Ribosomes
b. Peroxisomes d. Oxyhydrosomes ;|
ANS: B ;|
Peroxisomes are so named because they usually contain enzymes that use oxygen to remove ;| ;| ;| ;| ;| ;| ;| ;| ;| ;| ;| ;| ;|
hydrogen atoms from specific substrates in an oxidative reaction that produces H2O2, which
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is a powerful oxidant and potentially destructive if it accumulates or escapes from
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peroxisomes. Ribosomes are RNA-protein complexes (nucleoproteins) that are synthesized
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in the nucleolus and secreted into the cytoplasm through pores in the nuclear envelope
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called nuclear pore complexes. Lysosomes are saclike structures that originate from the
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Golgi complex and contain more than 40 digestive enzymes called hydrolases, which
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catalyzebonds inproteins, lipids, nucleicacids, andcarbohydrates. Oxyhydrosomes are
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involved in enzyme production.
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4. Whichcell component iscapable ofcellular autodigestion when it isreleased during cell
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;| injury?
a. Ribosome c. Smoothendoplasmic reticulum ;| ;|
b. Golgi complex ;| d. Lysosomes ;|
;| ANS: D ;|
, The lysosomal membrane acts as a protective shield between the powerful digestive
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enzymes within the lysosome and the cytoplasm, preventing their leakage into the
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cytoplasmic matrix. Disruption of the membrane by various treatments or cellular injury
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leads to a release of the lysosomal enzymes, which can then react with their specific
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substrates,causing cellular self-digestion. Theotheroptions do not correctlydescribethis
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process.
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5. What is the sequence ofsteps inthe development ofa digestive enzyme bythe pancreas cells
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from the initial transcription to the release from the cell?
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a. The enzyme is transcribed fromDNA byRNA in the nucleus, proceeds to the
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ribosome for synthesis, and is transported in a secretory vesicle to the cell
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membrane.;|
b. The enzyme is transcribed from RNA by DNA in the nucleus, proceeds to the
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lysosome for synthesis, and is transported in an encapsulated membrane tothe cell
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membrane.;|
c. The enzyme is transcribed by the mitochondria in the nucleus, proceeds to the
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ribosome for synthesis, and is transported ina cytoskeletontothecell membrane.
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d. The enzyme is transcribed from DNA by RNA in the nucleus, proceeds to the
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Golgicomplex forsynthesis, and istransported ina cytosoltothe cell membrane.
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ANS: A ;|
Theenzyme is transcribed fromDNAbyRNAin the nucleus, proceeds to the ribosome for
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synthesis, and is transported in a secretory vesicle to the cell membrane. The other options
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do not correctly describe this process.
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PTS: ; | ; | 1 REF: Page 7 |Figure 1-5 ;| ;| ;| ;| ;|
6. During which phase ofthe cellcycle is DNAsynthesized?
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a. G1 c. G2
b. S d. M ; |
ANS: B ;|
The four designated phases of the cell cycle are: (1) the G1 phase (G = gap), which is the
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period between the M phase (M = mitosis) and the start ofDNAsynthesis; (2) the S phase (S =
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synthesis), during which DNA is synthesized in the cell nucleus; (3) the G2 phase, during
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which RNA and protein synthesis occurs, the period between the completion of DNA
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synthesis and the next phase (M); and (4) the M phase, which includes nuclear and
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cytoplasmic division.
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7. What organiccompound facilitates transportation across cell membranes byactingas
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;| receptors, transport channels for electrolytes, and enzymes to drive active pumps?
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a. Lipids c. Proteins
b. Proteases d. Carbohydrates ; |
ANS: C ;|
, Proteins act as (1) recognition and binding units (receptors) for substances moving in and out
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of the cell; (2) pores or transport channels for various electrically charged particles called
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ions or electrolytes and specific carriers for amino acids and monosaccharides; and
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(3) specific enzymes that drive active pumps that promote the concentration of certain ions,
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particularlypotassium (K+), within thecell while keeping concentrations ofother ions, for
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example, sodium (Na+), below the concentrations found in the extracellular environment.
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The other options do not correctly describe this process.
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8. Understanding the various steps of proteolytic cascades, such as caspase-mediated ;| ;| ;| ;| ;| ;| ;| ;| ;|
apoptosisand complement cascades, maybeuseful indesigningdrugtherapyfor which
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human diseases?
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a. Cardiacand vascular disorders ;| ;| ;|
b. Autoimmune and malignant disorders ;| ;| ;|
c. Gastrointestinalandrenaldisorders ;| ;| ;|
d. Endocrineand gastrointestinaldisorders ;| ;| ;|
ANS: B ;|
Understanding the various steps involved in this process is crucial for designing drug ;| ;| ;| ;| ;| ;| ;| ;| ;| ;| ;| ;|
interventions.Dysregulation ofproteases features prominentlyinmanyhuman diseases,
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including cancer, autoimmunity, and neurodegenerative disorders. The other options do not
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correctly describe this process.
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9. Whichstructureprevents water-soluble molecules fromentering cells acrossthe plasma
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membrane?
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a. Carbohydrate chains ;| c. Membrane channel proteins ;| ;|
b. Glycoproteinchannels ;| d. Lipid bilayer ;| ;|
ANS: D ;|
The bilayer’s structure accounts for one of the essential functions of the plasma membrane.
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It is impermeable to most water-soluble molecules (molecules that dissolvein water) because
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the water-soluble molecules are insoluble in the oily core region. The bilayer serves as a
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barrier to the diffusion of water and hydrophilic substances while allowing lipid-soluble
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molecules, such as oxygen (O2) and carbon dioxide (CO2), to diffuse through it readily.
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The other options do not correctly describe this process.
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10. The fluid mosaic modelexplains:
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a. How a cell membrane functions ;| ;| ;| ;|
b. Whyour bodies appear to be solid ;| ;| ;| ;| ;| ;|
c. Howtissue isdifferentiated ;| ;| ;|
d. Howfluid moves between the intracellular and extracellular compartments
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ANS: A ;|
The fluid mosaic model accounts for the flexibility of cellular membranes, their self-
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sealingproperties,andtheir impermeabilityto manysubstances. Theremaining options
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do not explain the mosaic model.
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