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Chapter 1. Cell Biology

Erythrocytes use glycolysis primarily as a source of energy in the form of

A. ATP to power active membrane transport

B. ATP to maintain cytoskeleton integrity

C. NADH to power protein synthesis

D. NADPH to initiate DNA replication

E. NADH to reduce oxidized glutathione

Answer: A. B would be correct if it listed NADPH instead of ATP. C is incorrect because the cell does not make its own proteins. D is incorrect because RBCs lack nuclei and therefore do not replicate any DNA. E would be correct if it listed NADPH instead of NADH.

A defect in cholesterol metabolism or other sources of bile would cause difficulties in digestion because bile is needed for

A. Emulsification of dietary fat for easier access of stomach lipases

B. Denaturation of dietary proteins for easier digestion by proteases

C. Micelle incorporation of lipids for easier digestion by lipases

D. Neutralization of stomach acid

E. Stimulation of pancreatic secretions

Answer: C. The stomach does not produce lipases. Bile micelle incorporation is not related to protease activity. Bile does not affect the acidic pH of stomach effluent. Pancreas secretions are stimulated by hormones, not bile.

Cyclins are proteins that serve as signals to control progression of cells around the cell cycle. Cyclin signals are transmitted via

A. Histone acetylases

B. Protein kinases

C. DNA methylases

D. Specific proteases

E. Small interfering RNAs (siRNA)

Answer: B. Histone acetylases and DNA methylases play a role in DNA configuration, while proteases are not involved in cell messaging. siRNA is part of gene expression, not directly related to cell messaging.

Which of the following is a correct match?

A. G cell—pepsinogen

B. Chief cell—gastrin

C. Parietal cell—HCl and intrinsic factor

D. Mucous cells—cholecystokinin

Answer: C. G cell = gastrin, chief cell = pepsinogen, parietal cell = HCl and intrinsic factor, mucous cell = mucus/bicarbonate.


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