Chapter 1: Cellular Biology MULTIPLE CHOICE 1. Which statement best describes the cellular function of metabolic absorption? a. Cells can produce proteins. c. Cells can take in and use nutrients. b. Cells can secrete digestive enzymes. d. Cells can synthesize fats. CORRECT ANSWER AND EXPLANATION C In metabolic absorption, all cells take in and use nutrients and other substances from their surroundings. The remaining options are not inclusive in their descriptions of cellular metabolic absorption. TOTAL POINTS 1 ACCURATE REFFERENCE Page 2 2. Most of a cell’s genetic information, including RNA and DNA, is contained in the: a. Mitochondria c. Nucleolus b. Ribosome d. Lysosome CORRECT ANSWER AND EXPLANATION C The nucleus contains the nucleolus, a small dense structure composed largely of RNA, most of the cellular DNA, and the DNA-binding proteins, such as the histones, which regulate its activity. The other options do not contain most of a cell’s genetic information. TOTAL POINTS 1 ACCURATE REFFERENCE Page 2 3. Which component of the cell produces hydrogen peroxide (H2O2) by using oxygen to remove hydrogen atoms from specific substrates in an oxidative reaction? a. Lysosomes c. Ribosomes b. Peroxisomes d. Oxyhydrosomes CORRECT ANSWER AND EXPLANATION 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 is a powerful oxidant and potentially destructive if it accumulates or escapes from peroxisomes. Ribosomes are RNA-protein complexes (nucleoproteins) that are synthesized in the nucleolus and secreted into the cytoplasm through pores in the nuclear envelope called nuclear pore complexes. Lysosomes are saclike structures that originate from the Golgi complex and contain more than 40 digestive enzymes called hydrolases, which catalyze bonds in proteins, lipids, nucleic acids, and carbohydrates. Oxyhydrosomes are involved in enzyme production. TOTAL POINTS 1 ACCURATE REFFERENCE Page 8 4. Which cell component is capable of cellular autodigestion when it is released during cell injury? NSG 5003 APEA a. Ribosome c. Smooth endoplasmic reticulum b. Golgi complex d. Lysosomes CORRECT ANSWER AND EXPLANATION D NSG 5003 APEA The lysosomal membrane acts as a protective shield between the powerful digestive enzymes within the lysosome and the cytoplasm, preventing their leakage into the cytoplasmic matrix. Disruption of the membrane by various treatments or cellular injury leads to a release of the lysosomal enzymes, which can then react with their specific substrates, causing cellular self-digestion. The other options do not correctly describe this process. TOTAL POINTS 1 ACCURATE REFFERENCE Pages 7-8 5. What is the sequence of steps in the development of a digestive enzyme by the pancreas cells from the initial transcription to the release from the cell? a. The enzyme is transcribed from DNA by RNA in the nucleus, proceeds to the ribosome for synthesis, and is transported in a secretory vesicle to the cell membrane. b. The enzyme is transcribed from RNA by DNA in the nucleus, proceeds to the lysosome for synthesis, and is transported in an encapsulated membrane to the cell membrane. c. The enzyme is transcribed by the mitochondria in the nucleus, proceeds to the ribosome for synthesis, and is transported in a cytoskeleton to the cell membrane. d. The enzyme is transcribed from DNA by RNA in the nucleus, proceeds to the Golgi complex for synthesis, and is transported in a cytosol to the cell membrane. CORRECT ANSWER AND EXPLANATION A The enzyme is transcribed from DNA by RNA in the nucleus, proceeds to the ribosome for synthesis, and is transported in a secretory vesicle to the cell membrane. The other options do not correctly describe this process. TOTAL POINTS 1 ACCURATE REFFERENCE Page 7 | Figure 1-5 6. During which phase of the cell cycle is DNA synthesized? a. G1 c. G2 b. S d. M CORRECT ANSWER AND EXPLANATION B The four designated phases of the cell cycle are: (1) the G1 phase (G = gap), which is the period between the M phase (M = mitosis) and the start of DNA synthesis; (2) the S phase (S = synthesis), during which DNA is synthesized in the cell nucleus; (3) the G2 phase, during which RNA and protein synthesis occurs, the period between the completion of DNA synthesis and the next phase (M); and (4) the M phase, which includes nuclear and cytoplasmic division. TOTAL POINTS 1 ACCURATE REFFERENCE Page 37 7. What organic compound facilitates transportation across cell membranes by acting as receptors, transport channels for electrolytes, and enzymes to drive active pumps? a. Lipids c. Proteins b. Proteases d. Carbohydrates CORRECT ANSWER AND EXPLANATION C