Exam 2 Study Questions

Which fatty acid is considered essential and must be supplied by the diet?

• Linoleic Acid

• Arachidonic acid

• N-9 fatty acid

• Oleic acid

In what form is most body fat stored?

• Fatty acids

• Triacylglycerols (TAG)

• Cholesterol

• Phospholipids

Which of the following is correct about identifying the position of double bonds?

• 18:2Δ9,12 is based on the Omega (ω) system

• In the 18:2 Δ9,12, “18” indicates the total number of carbon atoms

• 18:2 ω-6 is based on the Delta (Δ) system

• In the 18:2 ω-6, “6” indicates the total number of double bonds

Which of the following is NOT correct about fatty acid synthesis?

• The starters of fatty acid synthesis include acetyl-CoA and malonyl-CoA

• Condensing enzymes and acyl carrier proteins are essential for fatty acid synthesis

• NADPH is a hydrogen donor during fatty acid synthesis

• The formation of malonyl-CoA through the carboxylation of acetyl-CoA by acetyl-CoA carboxylase is essential.

• Acetyl-CoA is the donor of 2 carbon units during atty acid synthesis.

Which of the following is correct about the regulation of fatty acid synthesis?

• Insulin inhibits fatty acid synthesis by activating acetyl-CoA carboxylase

• Long-chain acyl CoA (e.g., palmitoyl-CoA) increases the activity of acetyl-CoA carboxylase

• Glucagon decreases the activity of acetyl-CoA carboxylase

• Citrates activate acetyl-CoA carboxylase through allosteric regulation

• High levels of plasma free fatty acids (FFA) are associated with increased lipogenesis

Which of the following is NOT correct about cholesterol?

• It is the precursor of steroid hormones

• It is found in animal food products

• The sources of cholesterol in the human body include diet as well as biosynthesis

• Vitamin D can be synthesized from cholesterol in the body

• All of the above are correct

Which of the following is correct about cholesterol synthesis?

• The starting molecule is malonyl-CoA

• HMG CoA reductase is a rate-limiting enzyme of cholesterol synthesis

• It occurs in the mitochondria

• Mevalonate and cholesterol increase the activity of HMG CoA reductase

• The high dietary cholesterol intake increases biosynthesis of cholesterol mainly in the liver

Which of the following explains PPARγ?

• It is only located in adipose tissues

• It stimulates fatty acid catabolism

• It is the first discovered and most studied PPAR

• It forms a heterodimer with Retinoid X receptor (RXR)

Which of the following is involved in suppressing bile acid synthesis?

• Liver X receptors (LXRs)

• Peroxisome proliferator-activated receptor α (PPARα)

• Sterol regulatory element binding protein (SREBP)

• Farnesoid X receptor (FXR)

• None of these are involved in suppressing bile acid synthesis

Which of the following is correct about the sterol regulatory element binding protein (SREBP)?

• SREBP-1 is involved in cholesterol biosynthesis

• When cellular cholesterol declines below a critical level, HMG CoA reductase is up-regulated through SREBP

• SREBP-2 is involved in the lipid biosynthesis

• SREBP is involved in lipid catabolism