phospholipids and ketone bodies

Which of the following is a structural component of nerve tissue?

• A. Glycerophospholipid

• B. Sphingomyelin

• C. Cholesterol

• D. Prostaglandin

• Answer: B. Sphingomyelin
  Explanation: Sphingomyelin is the major sphingophospholipid in nerve tissue, essential for its structural integrity.

Which enzyme deficiency causes Niemann-Pick Disease?

• A. Phospholipase A2

• B. Sphingomyelinase

• C. Glucose-6-phosphatase

• D. Lipase

Answer: B. Sphingomyelinase
Explanation: Sphingomyelinase deficiency leads to the accumulation of sphingomyelin, causing Niemann-Pick Disease.

What is the primary energy source during prolonged fasting?

• A. Glycogen

• B. Fatty acids

• C. Ketone bodies

• D. Glucose

• Answer: C. Ketone bodies
  Explanation: During prolonged fasting, ketone bodies serve as an alternative energy source, especially for the brain.

Which condition is characterized by a fruity odor on the breath?

• A. Ketosis

• B. Ketoacidosis

• C. Hyperglycemia

• D. Hypoglycemia

Answer: B. Ketoacidosis
Explanation: The fruity odor results from increased acetone production in diabetic ketoacidosis.

What role do phospholipids play in bile?

• A. Emulsification of fats

• B. Digestion of carbohydrates

• C. Synthesis of cholesterol

• D. Activation of enzymes

Answer: A. Emulsification of fats
Explanation: Phospholipids in bile help emulsify fats, aiding in lipid digestion and absorption.

Which ketone body is a byproduct and not used for energy?

• A. Acetone

• B. Acetoacetate

• C. β-hydroxybutyrate

• D. Pyruvate

Answer: A. Acetone
Explanation: Acetone is a non-metabolizable byproduct of ketogenesis, excreted via breath or urine.

Which enzyme is critical for ketone body usage in peripheral tissues?

• A. Thiophorase

• B. Pyruvate dehydrogenase

• C. Lipase

• D. Hexokinase

Answer: A. Thiophorase
Explanation: Thiophorase catalyzes the conversion of acetoacetate to acetyl-CoA for use in the TCA cycle.

What is the primary metabolic role of prostaglandins?

• A. Energy production

• B. Hormonal storage

• C. Local signaling

• D. Blood glucose regulation

Answer: C. Local signaling
Explanation: Prostaglandins act locally to mediate inflammation, pain, and other processes.

Which molecule is a precursor for ketogenesis?

• A. Pyruvate

• B. Acetyl-CoA

• C. Lactate

• D. Oxaloacetate

Answer: B. Acetyl-CoA
Explanation: Acetyl-CoA, derived from fatty acid oxidation, is channeled into ketone body synthesis during fasting.

Which tissue cannot utilize ketone bodies for energy?

• A. Skeletal muscle

• B. Liver

• C. Brain

• D. Cardiac muscle

• Answer: B. Liver
  Explanation: The liver lacks thiophorase and cannot metabolize ketone bodies for energy.

Regarding phospholipids:
A. Phospholipids are amphipathic molecules.
B. Sphingomyelin is a glycerophospholipid.
C. Phospholipases degrade phospholipids into messengers.
D. Niemann-Pick disease results from phospholipase A2 deficiency.
E. Phospholipids are primary components of cell membranes.

A. Phospholipids are amphipathic molecules. (True)
B. Sphingomyelin is a glycerophospholipid. (False)
C. Phospholipases degrade phospholipids into messengers. (True)
D. Niemann-Pick disease results from phospholipase A2 deficiency. (False)
E. Phospholipids are primary components of cell membranes. (True)

Regarding glycolipids and prostaglandins:
A. Glycolipids are most abundant in nerve tissues.
B. Glycolipids play a role in cellular signaling.
C. Prostaglandins are stable molecules with a long half-life.
D. Prostaglandins are synthesized from arachidonic acid.
E. Glycolipids are the primary energy storage molecules.

A. Glycolipids are most abundant in nerve tissues. (True)
B. Glycolipids play a role in cellular signaling. (True)
C. Prostaglandins are stable molecules with a long half-life. (False)
D. Prostaglandins are synthesized from arachidonic acid. (True)
E. Glycolipids are the primary energy storage molecules. (False)

Regarding ketone body production:
A. Ketone bodies are synthesized in the liver.
B. Acetoacetate is converted to β-hydroxybutyrate in peripheral tissues.
C. Ketone body production is elevated during prolonged fasting.
D. Ketogenesis is triggered by an excess of acetyl-CoA.
E. Ketone bodies are excreted in urine during ketosis.

A. Ketone bodies are synthesized in the liver. (True)
B. Acetoacetate is converted to β-hydroxybutyrate in peripheral tissues. (False)
C. Ketone body production is elevated during prolonged fasting. (True)
D. Ketogenesis is triggered by an excess of acetyl-CoA. (True)
E. Ketone bodies are excreted in urine during ketosis. (True)

Regarding the utilization of ketone bodies:
A. Skeletal muscle can use ketone bodies for energy.
B. The brain utilizes ketone bodies during starvation.
C. The liver can metabolize ketone bodies for its energy needs.
D. Acetone is metabolized to ATP in peripheral tissues.
E. Thiophorase is necessary for ketone body utilization.

A. Skeletal muscle can use ketone bodies for energy. (True)
B. The brain utilizes ketone bodies during starvation. (True)
C. The liver can metabolize ketone bodies for its energy needs. (False)
D. Acetone is metabolized to ATP in peripheral tissues. (False)
E. Thiophorase is necessary for ketone body utilization. (True)

Regarding clinical implications of ketogenesis:
A. Diabetic ketoacidosis occurs due to excessive ketone production.
B. Ketonemia is the presence of ketone bodies in the blood.
C. Fruity breath in ketoacidosis is caused by β-hydroxybutyrate.
D. Prolonged fasting results in elevated blood ketone levels.
E. Excess ketone bodies can lead to metabolic acidosis.

A. Diabetic ketoacidosis occurs due to excessive ketone production. (True)
B. Ketonemia is the presence of ketone bodies in the blood. (True)
C. Fruity breath in ketoacidosis is caused by β-hydroxybutyrate. (False)
D. Prolonged fasting results in elevated blood ketone levels. (True)
E. Excess ketone bodies can lead to metabolic acidosis. (True)

Regarding phospholipid degradation:
A. Phospholipases hydrolyze phosphodiester bonds in phospholipids.
B. Phospholipase A2 releases arachidonic acid from membranes.
C. Defective phospholipid degradation affects prostaglandin synthesis.
D. Sphingomyelin is degraded by phospholipase C.
E. Phospholipids are broken down only in lysosomes.

A. Phospholipases hydrolyze phosphodiester bonds in phospholipids. (True)
B. Phospholipase A2 releases arachidonic acid from membranes. (True)
C. Defective phospholipid degradation affects prostaglandin synthesis. (True)
D. Sphingomyelin is degraded by phospholipase C. (False)
E. Phospholipids are broken down only in lysosomes. (False)

Regarding glycolipids:
A. Glycolipids are integral components of the myelin sheath.
B. Glycolipids contain a glycerol backbone.
C. Glycolipids are essential for cell-cell communication.
D. Tay-Sachs disease involves glycolipid accumulation.
E. Glycolipids are synthesized in the mitochondria.

• A. Glycolipids are integral components of the myelin sheath. (True)
  B. Glycolipids contain a glycerol backbone. (False)
  C. Glycolipids are essential for cell-cell communication. (True)
  D. Tay-Sachs disease involves glycolipid accumulation. (True)
  E. Glycolipids are synthesized in the mitochondria. (False)

Regarding prostaglandins:
A. Prostaglandins are derived from polyunsaturated fatty acids.
B. Prostaglandins act systemically with long-lasting effects.
C. Cyclooxygenase enzymes are required for prostaglandin synthesis.
D. Prostaglandins regulate inflammatory and immune responses.
E. NSAIDs inhibit prostaglandin degradation.

A. Prostaglandins are derived from polyunsaturated fatty acids. (True)
B. Prostaglandins act systemically with long-lasting effects. (False)
C. Cyclooxygenase enzymes are required for prostaglandin synthesis. (True)
D. Prostaglandins regulate inflammatory and immune responses. (True)
E. NSAIDs inhibit prostaglandin degradation. (False)

Regarding ketone body metabolism:
A. Acetone is the main energy-yielding ketone body. (False)
B. Ketone body synthesis occurs in the cytoplasm. (False)
C. β-hydroxybutyrate is converted to acetoacetate in peripheral tissues. (True)
D. High ketone levels in blood can lead to metabolic acidosis. (True)
E. Ketone bodies are used preferentially by cardiac muscle over glucose. (

A. Acetone is the main energy-yielding ketone body. (False)
B. Ketone body synthesis occurs in the cytoplasm. (False)
C. β-hydroxybutyrate is converted to acetoacetate in peripheral tissues. (True)
D. High ketone levels in blood can lead to metabolic acidosis. (True)
E. Ketone bodies are used preferentially by cardiac muscle over glucose. (False)

Regarding diabetic ketoacidosis (DKA):
A. DKA is caused by insufficient insulin levels.
B. Ketonuria is a common feature of DKA.
C. DKA leads to alkalosis due to increased ketone production
D. Fruity-smelling breath in DKA is due to acetone.
E. DKA is more common in Type 2 diabetes than Type 1.

A. DKA is caused by insufficient insulin levels. (True)
B. Ketonuria is a common feature of DKA. (True)
C. DKA leads to alkalosis due to increased ketone production. (False)
D. Fruity-smelling breath in DKA is due to acetone. (True)
E. DKA is more common in Type 2 diabetes than Type 1. (False)

What is the difference between glycerophospholipids and sphingophospholipids?

Answer: Glycerophospholipids have a glycerol backbone, while sphingophospholipids have a sphingosine backbone.
Explanation: The structural difference determines their functions, with glycerophospholipids being more common in general cell membranes and sphingophospholipids predominant in nerve tissue.

What triggers the production of ketone bodies in the liver?

Answer: Ketone bodies are produced during prolonged fasting or carbohydrate restriction due to an increase in fatty acid oxidation and acetyl-CoA levels.
Explanation: The liver synthesizes ketone bodies to provide alternative energy sources when glucose availability is low.

Why can the liver produce but not utilize ketone bodies?

Answer: The liver lacks the enzyme thiophorase, which is necessary for converting acetoacetate to acetyl-CoA.
Explanation: While the liver produces ketone bodies for peripheral tissue use, it cannot metabolize them due to this enzymatic deficiency.

What is Niemann-Pick disease, and which enzyme deficiency causes it?

Answer: Niemann-Pick disease is a lysosomal storage disorder caused by sphingomyelinase deficiency, leading to sphingomyelin accumulation.
Explanation: The disease manifests in two forms: Type A (severe neurodegeneration) and Type B (chronic visceral involvement).

What is the clinical significance of ketone bodies during starvation?

Answer: Ketone bodies provide an alternative energy source for tissues like the brain and muscles, reducing the reliance on glucose and sparing protein breakdown.
Explanation: By utilizing ketone bodies, the body conserves critical glucose and protein reserves during prolonged fasting.