Cholestrol metabolism

​A 45-year-old software professional, sedentary lifestyle, eats outside food 4–5 times/week, HDL 32 mg/dL, LDL 165 mg/dL. Why does this happen?

Open Ended

Why is cholesterol considered an important molecule in mammalian biology?

Multiple Choice

Which of the following is NOT a function of cholesterol in the human body?

• Precursor of steroid hormones

• Precursor of bile acids

• Precursor of vitamin D

• Source of glucose

Multiple Choice

Which organ is the major site for de novo cholesterol synthesis in the human body?

• Liver

• Intestine

• Kidney

• Heart

Multiple Select

Which of the following are key building blocks or intermediates in the biosynthesis of cholesterol?

• Acetyl CoA

• Isopentenyl pyrophosphate

• Squalene

• Glucose

Open Ended

Explain the three main stages of cholesterol biosynthesis.

Multiple Choice

What enzyme catalyzes the condensation of two molecules of acetyl CoA to form acetoacetyl CoA?

• Thiokinase

• Thiolase

• Synthase

• Reductase

Open Ended

Describe the role of HMG-CoA reductase in cholesterol biosynthesis and explain what happens to HMG-CoA in mitochondria.

Multiple Choice

Which enzyme is inhibited by cholesterol-lowering statin drugs such as Lovastatin?

• HMG-CoA reductase

• Mevalonate kinase

• Squalene synthase

• Isopentenyl pyrophosphate isomerase

Open Ended

Describe the role of isopentenyl pyrophosphate in cholesterol biosynthesis.

Multiple Choice

Which of the following compounds are formed by the reaction of C5 units of isopentenyl pyrophosphate and C5 units of dimethylallyl pyrophosphate?

• Geranyl pyrophosphate

• Farnesyl pyrophosphate

• Squalene

• Mevalonate

Multiple Choice

Which of the following steps in cholesterol biosynthesis involves the use of NADPH?

• Conversion of farnesyl pyrophosphate to squalene

• Conversion of mevalonate to isopentenyl pyrophosphate

• Isomerization of isopentenyl pyrophosphate

• Formation of geranyl pyrophosphate

Open Ended

Explain the conversion process from squalene to lanosterol, highlighting the key intermediates.

Multiple Choice

Lanosterol is converted into cholesterol in a multistep process. How many steps are involved in this conversion?

• 5

• 10

• 19

• 25

Multiple Choice

Which enzyme is a target for some cardiovascular drugs in the formation of mevalonate?

• HMG-CoA synthase

• HMG-CoA reductase

• Mevalonate kinase

• Acetyl-CoA carboxylase

Open Ended

Describe the role of pyrophosphate in the formation of activated isoprene.

Multiple Select

Which molecules are directly involved in the formation of squalene from farnesyl pyrophosphate?

• NADPH

• ATP

• H+

• NADP+

Multiple Choice

Which enzyme is responsible for converting squalene to squalene 2,3-epoxide in the steroid nucleus formation pathway?

• Cyclase

• Squalene monooxygenase

• Acyl transferase

• HMG-CoA reductase

Open Ended

Explain the significance of cholesteryl esters being more hydrophobic than cholesterol. How does this property affect their role in the body?

Multiple Select

Which of the following are required for the de novo synthesis of cholesterol?

• NADPH

• ATP

• O2

• FADH2

Multiple Choice

Which of the following statements about the regulation of cholesterol synthesis is correct?

• Insulin activates HMG-CoA reductase by inducing protein phosphatase.

• Feeding inhibits cholesterol synthesis by reducing acetyl-CoA availability.

• Protein kinase A activates HMG-CoA reductase.

• NADPH is not required for cholesterol synthesis.

Open Ended

Reflecting on today's lesson, how do you think cholesterol metabolism impacts overall health and disease prevention?

Multiple Choice

Which of the following is NOT a function of cholesterol in mammals?

• Precursor of steroid hormones

• Precursor of bile acids

• Precursor of vitamin D

• Source of glucose