Lipid Synthesis and Absorption

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Questions and Answers

What is the fate of chylomicron residues after triglyceride breakdown?

They are stored in muscle tissue

They are released into the bloodstream

They bind to receptors in the liver and are taken in by endocytosis (correct)

They are transported back to adipose tissue

What is the name of the condition resulting from inadequate uptake of chylomicron residues by the liver?

Type III hyperlipoproteinemia

Familial lipoprotein lipase deficiency

Type I hyperlipoproteinemia

Familial dysbetalipoproteinemia (correct)

What is the purpose of beta-oxidation of fatty acids?

To store fatty acids in adipose tissue

To transport fatty acids to the liver

To synthesize fatty acids

To break down fatty acids into 2-carbon units (correct)

How are fatty acids with more than 12 carbons transported into the mitochondria?

Through the carnitine shuttle Signup and view all the answers

Where is carnitine primarily stored in the body?

Muscles Signup and view all the answers

What is the purpose of the carnitine shuttle?

To transport fatty acids into the mitochondria Signup and view all the answers

What is the name of the condition resulting from lipoprotein lipase or apoC-II deficiency?

Familial lipoprotein lipase deficiency Signup and view all the answers

Where are fatty acids with 12 or fewer carbons transported from?

Directly into the mitochondria Signup and view all the answers

At what age should adults at average risk of coronary artery disease start having their cholesterol levels checked?

18 Signup and view all the answers

What is the enzyme responsible for adding CoA to fatty acids?

Acy-CoA synthetase Signup and view all the answers

What is the optimal pH for lipase enzymes in the stomach?

4-6 Signup and view all the answers

What is the primary function of apoB-48 in lipid synthesis?

To package lipid droplets in the mucosal cells Signup and view all the answers

What percentage of ingested lipids are triacylglycerols (TAG)?

More than 90% Signup and view all the answers

What is the fate of short- and medium-length fatty acids in the bloodstream?

They are bound to albumin and transported to tissues Signup and view all the answers

What is the primary function of lipoprotein lipase in triglyceride metabolism?

To break down triglycerides into fatty acids and glycerol Signup and view all the answers

What is the function of essential fatty acids in the body?

Waterproofing skin Signup and view all the answers

Where is cholesterol found in cell membranes?

Between phospholipids Signup and view all the answers

What is the product of glycerol uptake in the liver?

Glycerol-3-phosphate Signup and view all the answers

What is the primary function of apo-CII in triglyceride metabolism?

To activate lipoprotein lipase Signup and view all the answers

What is the consequence of a linoleic acid deficiency?

Scaly skin and hair loss Signup and view all the answers

What is the function of lipids in the structure of plant perfumes?

Fragrance Signup and view all the answers

What is the destination of fatty acids released from chylomicrons in peripheral tissues?

They are taken up by skeletal muscle and adipose tissue cells Signup and view all the answers

What is the primary function of acyl transferases in lipid synthesis?

To bind fatty acids to monoacylglycerols, free cholesterol, and lysophospholipids Signup and view all the answers

Which of the following is a fat-soluble vitamin?

Vitamin K Signup and view all the answers

Study Notes

Synthesis and Absorption of Lipids

Fatty acids are activated by adding CoA via the enzyme acyl-CoA synthetase
Activated fatty acids bind to monoacylglycerols, free cholesterol, and lysophospholipids via acyl transferases
Short- and medium-length fatty acids are not esterified but enter the bloodstream directly and are transported to tissues by binding to albumin
Resynthesized triglycerides and cholesterol esters are highly hydrophobic and are packaged into chylomicrons with phospholipids, free cholesterol, and apoB-48
Chylomicrons are exocytosed from intestinal mucosal cells into the lymphatic circulation and from there into the general circulation
Triglycerides in chylomicrons are broken down to fatty acids and glycerol by lipoprotein lipase on the surface of capillary endothelium
Fatty acids can be taken up by muscle and adipose tissue cells or bind to albumin and be transported until taken up into the cell
Glycerol is taken up by the liver and used in the synthesis of glycerol-3-phosphate, which can undergo glycolysis or gluconeogenesis via dihydroxyacetonephosphate

Beta Oxidation of Fatty Acids

Beta-oxidation is a metabolic pathway in which fatty acids are catabolized into 2-carbon units in mitochondria, essential for meeting energy needs
Fatty acids with 12 or fewer carbons can enter the mitochondria directly, while those with more than 12 carbons require the carnitine shuttle transporter system

Essential Fatty Acids (EFAs)

EFAs are necessary for a healthy body and cannot be synthesized by the body
Alpha-linolenic acid (an omega-3 fatty acid) and linoleic acid (an omega-6 fatty acid) are two important EFAs
Foods containing EFAs include fish and shellfish products, flax seeds, hemp oil, soy oil, canola oil, chia seeds, pumpkin seeds, sunflower seeds, leafy vegetables, and walnuts

Functions of Lipids

Lipids provide high energy storage
They create waterproof layers in plants and form an insulating layer on nerve cells (myelin)
They create a shock-absorbing layer on the bodies of animals
Cholesterol is found in cell membranes between phospholipids
Steroids are found in the structure of estrogen, testosterone, and cortisol
Fragrance is found in the structure of plant perfumes
Fat-soluble vitamins A, D, E, and K are essential for various bodily functions

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Description

This quiz covers the synthesis and absorption of lipids, including the activation of fatty acids, re-synthesis of triglycerides and phospholipids, and transportation of short- and medium-length fatty acids in the bloodstream.