Membrane Transport
Which of the following properly describes a type of transporter?
A. Pores, closed except when bound to a specific ligand
B. Gated channels, dependent on the number of molecules that are going to betransported.
C. Transporters, open to one side at a time, affinity for the substrate changes.
D. Pores, activated by only certain membrane potentials.
C. Transporters, open to one side at a time, affinity for the substrate changes.
A signaling pathway is triggered by an Extracellular receptor. Which of the following ligands is likely to trigger this signal?
A. Cortisol
B. Thyroid Hormone
C. Insulin
D. Aldosterone
C. Insulin
Which of the following best describes the role of NADH and FADH₂ in metabolism?
A. They store phosphate groups for energy transfer
B. They act as substrates for glycolysis
C. They shuttle electrons from fuel oxidation to the electron transport chain
D. They catalyze reactions in the TCA cycle
C. They shuttle electrons from fuel oxidation to the electron transport chain
Which of the following enzymes does NOT catalyze one of the irreversible steps in glycolysis?
A. Hexokinase
B. Glucokinase
C. Phosphofructokinase-1
D. Phosphoglycerate kinase
D. Phosphoglycerate kinase
What is the role of ketone bodies?
A. Fuel used by brain during starvation.
B. Fuel used by the liver during starvation.
C. It is exhaled out of the lungs as a waste product.
D. Fuel used by RBCs during starvation.
A. Fuel used by brain during starvation.
Consider the sodium pump. Which of the following modes of transport is responsible forgetting glucose into the cell?
A. Simple Diffusion
B. Primary Active Transport
C. Secondary Active Transport, symport
D. Secondary Active Transport, antiport
C. Secondary Active Transport, symport; the existing gradient of Sodium drives the transport of glucose (secondary). The sodium gradient is achieved by Na-K ATPase pump that requires energy (active). Both sodium and glucose are entering the cell(symport).
Which of the following is true regarding the G alpha subunits of the G-protein-coupled receptors?
A. The subunits are localized to the amino end of the receptor.
B. Gq is necessary for the activation of adenylyl cyclase
C. Gi is essential for activating PKA
D. Ga is necessary for the inhibition of adenylyl cyclase.
E. Gq aids in the activation of PLC
E. Gq aids in the activation of PLC
In a pathway A → B → C, what does it mean if the overall ΔG from A → C is negative?
A. The pathway requires external energy input.
B. The reaction from B → C must be endergonic.
C. The entire pathway proceeds spontaneously.
D. The reaction from A → B must be irreversible.
C. The entire pathway proceeds spontaneously.
A patient was recently admitted to the hospital for liver failure. What is something that could be happening to him?
A. Excess conversion of pyruvate to lactate.
B. RBCs make increased amounts of lactate.
C. Insufficient conversion of lactate to pyruvate.
D. Insufficient conversion of lactate to glucose.
A. Excess conversion of pyruvate to lactate.
While there is a buildup of lactate, it is not through overproduction of lactate.
B. RBCs make increased amounts of lactate.
RBCs probably will not in
C. Insufficient conversion of lactate to pyruvate.
This is what the heart does.
D. Insufficient conversion of lactate to glucose.
Lactate buildup can lead to lactic acidemia!
Which is FALSE about ketone bodies formation?
A. It is stimulated by high FA levels in the blood.
B. It is inhibited by high acetyl CoA in the cell.
C. It is stimulated by high ATP levels.
D. It is inhibited by malonyl CoA.
B. It is inhibited by high acetyl CoA in the cell.
Ketone body synthesis is stimulated by high acetal CoA levels.
A patient presents to the emergency room with a persistent cough and noticeable wheezing.You go over the patient's medical history, and he notes that he has cystic fibrosis. What type of transport is affected in this patient?
A. Active transport of calcium ions into the cell.
B. Potassium secondary active transport allows for proper lung function.
C. Facilitated diffusion of potassium.
D. Chloride transport through ATP hydrolysis.
D. Chloride transport through ATP hydrolysis.
Which of the following would not be a part of the pathway induced by Leptin binding to its receptor?
A. Homodimerization
B. JAK 2 phosphorylation
C. STAT recruitment
D. Heterodimerization
A. Homodimerization
How do insulin and glucagon act as counter-regulatory hormones?
A. Insulin promotes catabolism while glucagon promotes anabolism
B. Insulin lowers blood glucose by promoting uptake; glucagon raises it by stimulating glucose production
C. Both hormones stimulate glycogen synthesis
D. Glucagon inhibits insulin secretion directly
B. Insulin lowers blood glucose by promoting uptake; glucagon raises it by stimulating glucose production
During intense exercise, muscle cells increasetheir calcium levels. What effect does this have onthe TCA cycle?
A. Inhibits isocitrate dehydrogenase
B. Activates α-ketoglutarate dehydrogenase
C. Inhibits pyruvate dehydrogenase kinase
D. Decreases succinate formation
B. Activates α-ketoglutarate dehydrogenase
Ca²⁺ activates key TCA enzymes to meet energy demand.
Which is FALSE about malonyl CoA?
A. Produced from acetyl CoA during FA oxidation.
B. Inhibits synthesis of FA.
C. Inhibits production of fatty acyl carnitine.
D. Prevents cells from breaking down the FA that was just made.
B. Inhibits synthesis of FA.
Malonyl CoA inhibits FA oxidation.
A certain molecule X can undergo simple diffusion. Which of the following is true when considering the limits of this type of transport?
A. The diffusion is limited only to the concentration of molecule X. Simple diffusion does not require transporters to be present.
B. The diffusion is limited by the number of transporters.
C. The diffusion is limited by the capacity of the transporters.
D. The diffusion is limited by both the capacity and the number of transporters.
A. The diffusion is limited only to the concentration of molecule X. Simple diffusion does not require transporters to be present.
A 32 y/o man presents to your clinic with severe watery diarrhea and dehydration, and youbegin to suspect cholera. What would likely be causing his symptoms?
A. Overactivation of G-alpha q
B. Decreased production of cAMP
C. The inhibition of Adenylyl Cyclase
D. Continuous production of cAMP.
D. Continuous production of cAMP.
Which of the following best compares glycogen break downduring exercise vs. fight-or-flight stimulation?
A. Both are stimulated by insulin
B. Exercise activates breakdown via glucagon; fight-or-flight viaepinephrine
C. Muscle uses epinephrine signaling; liver uses glucagon
D. Glycogen breakdown is inhibited in both cases
C. Muscle uses epinephrine signaling; liver uses glucagon
A drug that selectively inhibits Complex IV of the ETC is administered. Which of the following downstream effects is most likely?
A. Increased ATP production due to enhanced proton pumping
B. Decreased oxygen consumption and halted electron flow
C. Increased NADH oxidation and elevated ATP levels
D. Enhanced activity of ATP synthase due to proton buildup
B. Decreased oxygen consumption and halted electron flow
Complex IV is the final electron acceptor site; inhibition haltselectron flow and oxygen reduction, collapsing the proton gradient.
Mae has albumin deficiency. How does that affect the fatty acid oxidation in her body?
A. It is unaffected.
B. FADH2 cannot cross the inner mitochondrial membrane.
C. Long-chain fatty acids cannot cross the plasma membrane in cells.
D. Short-chain fatty acids cannot cross the blood brain barrier to the brain.
C. Long-chain fatty acids cannot cross the plasma membrane in cells.
2 medical students are arguing about the different glucose transporters. Student A claimsthat GLU 2 has the highest affinity because it needs the most glucose. In contrast, StudentB claims that GLU 4 has the highest affinity due to the glucose needs of RBCs. Which student is correct in their assessment?
A. Both students are correct.
B. Student A is correct
C. Student C is correct
D. Both students are incorrect
D. Both students are incorrect
A genetic mutation has led to abnormalities in multiple membrane proteins and pores thatfunction within the cell membrane. This mutation has some very detrimental consequences. Which of the following processes would you not expect to be affected?
A. Ions are moving from high to low concentration.
B. Small non-polar molecules move from high to low concentration.
C. Large polar molecules go from the extracellular to the intracellular space.
D. Small non-polar molecules that are moving from low to high concentration.
B. Small non-polar molecules move from high to low concentration.
Which of the following best explains the metabolic adaptations occurring in her liver during this prolonged fast?
A 28-year-old woman has been participating in a 48-hour water-only fast. She reports mild fatigue but no dizziness or confusion. Her labs show:
Blood glucose: 65 mg/dL
Serum ketones: elevated
Insulin: low
Glucagon: elevated
Cortisol: mildly elevated
A. Increased insulin promotes glycogen synthesis and lipogenesis
B. Elevated glucagon stimulates glycogenolysis and gluconeogenesis from amino acids
C. Low cortisol inhibits gluconeogenesis and promotes ketogenesis
D. High insulin and low glucagon favor fatty acid synthesis and glucose uptake
B. Elevated glucagon stimulates glycogenolysis and gluconeogenesis from amino acids
A patient with a mitochondrial myopathy presents with exercise intolerance and elevated blood lactate. Which of the following best explains the biochemical basis of this finding?
A. Increased oxidative phosphorylation leads to excess lactateproduction
B. Impaired ETC function forces reliance on anaerobic glycolysisfor ATP
C. Enhanced ATP synthase activity increases lactate clearance
D. Excess NADH from the ETC drives lactate formation
B. Impaired ETC function forces reliance on anaerobic glycolysis for ATP
ETC dysfunction reduces aerobic ATP production, shiftingmetabolism toward anaerobic glycolysis and lactate accumulation.
John is trying the keto diet, characterized by high fat and low carbohydrate intake. Which is true about the metabolism in John's body?
A. Accumulation of NAD+.
B. Acetyl CoA is used up very quickly.
C. Glucagon levels are high.
D. TCA cycle proceeds quickly.
C. Glucagon levels are high.