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
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
The stomach does not produce lipases. Bile micelle incorporation is not related to protease activity. Bile does not affect 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
E. Small, interfering RNAs (siRNA)
Histone acetylases and DNA methylases play a role in DNA configuration, while proteases are not involved in cell messenging. siRNA is part of gene expression, not directly related to cell messenging.
Which of the following is a correct match?
C. Parietal cell—HCl and intrinsic factor
D. Mucous cells—Cholecystekinin
G cell = gastrin, chief cell = pepsinogen, parietal cell = HCl and intrinsic factor, mucous cell = mucous/bicarbonate.
Platelet activation, muscle contraction, pancreatic secretion, and glycogen degradation act via which intracellular signal mechanism?
A. cAMP second messenger signaling
B. Calmodulin-induced calcium release
C. Protein kinase A activation
D. IP3 and DAG induced activation of protein kinase C
B is false because IP3 binding to endoplasmic reticulum releases calcium. A and C are false because they belong to the protein kinase A system.
Base deficit and serum lactate correlate with mortality in trauma by reflecting which of the following systemic changes from normal physiology?
A. Myoglobin induced ATN progressing to renal failure
B. Hyoperfused end organs relying on energy generated via aneorobic metabolism
C. Skeletal muscle sarcomere unregulated release of calcium and diacylglycerol
D. Injured organ trauma induced apoptosis releasing corresponding intravascular waste cellular products
Lactate production is associated with hypoperfusion in trauma. Myoglobin can cause ATN or renal failure in trauma but should not directly alter BD or lactate. Sarcomere release of calcium is implicated in malignant hyperthermia.
Which of the following clinical scenarios regarding metabolism is false or implausible?
A. An elderly patient on indomethacin, oxazepam, aspirin, and acetaminophen becomes jaundiced after overwhelming UDP-glucuronic acid transferase enzymes.
B. A 26-year-old female on oral contraceptives conceives after a course of antibiotics.
C. A 56-year-old with atrial fibrillation on warfarin is admitted with spontaneous hematemesis after starting ciprofloxacin/metronidazole therapy for diverticulitis.
D. A traumatically injured 38-year-old with no past medical history develops coma and cerebral infarction from profound hypoglycemia within 30 minutes of injury.
D is the false scenario. Glycogen stores can supply necessary glucose for anaerobic metabolism even in intense need for 20 to 90 minutes, after which depleted, anaerobic metabolism would attempt to meet the needs of the patient in scenario D.
Which mechanism explains ultraviolet light as a risk factor for skin cancers?
A. UV-B light is absorbed by DNA strands causing pyrimidine dimers
B. Increased number of melanocytes after prolonged tanning leads to proliferation errors
C. Vitamin D activation includes free radicals as a side product
D. Sunlight induces collagen breakdown, leading to sheer stress injury
B is incorrect because melanocyte number is constant as part of neural crest migration as an embryo. C is incorrect because free radicals are not involved. D is incorrect because collagen is unrelated to DNA sequence.
Select the incorrect statement from below.
A. Aerobic metabolism provides the most efficient, most proliferative process to convert glucose into ATP in humans.
B. Hepatocyte metabolism of toxins includes cytochrome P-450 enzymes, UDP-glucuronyl transferases, glutathione S-transferases, and sulfotransferases.
C. The entirety of chromosomal DNA is contained within the nucleus in formation with histone proteins.
D. Phase I reactions change endogenous substances solubility while Phase II reactions change their chemical structure.
Phase I reactions change chemical structure while Phase II reactions change solubility.