Lipid Metabolism Overview

What is the primary function of carnitine in fatty acid transport?

Which product is NOT generated during the β-oxidation of fatty acids?

Which step in β-oxidation involves the addition of water to form a secondary alcohol?

What happens during the second dehydrogenation step of β-oxidation?

How does the length of the acyl CoA molecule change after one cycle of β-oxidation?

Which oxidizing agent is used in the first dehydrogenation step of the β-oxidation pathway?

What type of reaction occurs during thiolysis in the β-oxidation pathway?

What is produced as the final product when a saturated fatty acid undergoes β-oxidation?

What is the main type of lipid consumed in the diet?

Which cellular component stores triacylglycerols?

What is produced alongside fatty acids during the hydrolysis of triacylglycerols?

Which process must occur for fatty acids to yield energy in the mitochondria?

What is required for the transport of fatty acids into the mitochondrial matrix?

What compounds are produced by the repeated oxidation of fatty acids?

What role does coenzyme A play in lipid metabolism?

In which tissue is triacylglycerol mobilization primarily observed?

Lipid Metabolism

Lipids are crucial for cellular metabolism due to their presence in every cell and their role as an energy-rich fuel source
Lipids can be stored in adipose tissue, which is a tissue containing large numbers of adipocytes (fat-storing cells)
Camels can survive for extended periods without food or water because they store fat in their humps, which provides energy
98% of dietary lipids consist of triacylglycerols (fats and oils)
The digestion of triacylglycerols involves enzymes like pancreatic lipase and gastric lipase, leading to the formation of micelles

Triacylglycerol Storage

Adipocytes are the primary storage site for triacylglycerols
Triacylglycerol mobilization involves the hydrolysis of stored triacylglycerols, releasing fatty acids and glycerol into the bloodstream

Glycerol metabolism

Glycerol, a byproduct of triacylglycerol mobilization can be metabolized through glycolysis, pyruvate oxidation, the Krebs cycle, and oxidative phosphorylation

Oxidation of fatty acids

Fatty acid breakdown for energy production involves three main stages: activation, transport, and oxidation
Activation involves bonding a fatty acid to coenzyme A, which occurs on the outer mitochondrial membrane
Transport requires the fatty acid to be transported into the mitochondrial matrix via a shuttle mechanism involving carnitine

B-Oxidation Pathway

The B-oxidation pathway is a cyclical process that oxidizes fatty acids, producing acetyl CoA, FADH2, and NADH
The pathway consists of four steps: dehydrogenation (x2), hydration, and thiolysis
The first dehydrogenation creates a double bond between the α and β carbons with FAD serving as the oxidizing agent
Hydration adds water across the trans double bond, producing a secondary alcohol at the β carbon
The second dehydrogenation converts the β-hydroxy group to a keto group with NAD+ as the oxidizing agent
Thiolysis breaks the fatty acid chain between the α and β carbons, producing acetyl-CoA and a shorter acyl-CoA molecule

This quiz explores the essential role of lipids in cellular metabolism, their storage in adipose tissue, and their significance as an energy source. It also covers the digestion of triacylglycerols and the metabolism of glycerol. Test your knowledge on how our bodies utilize and store these vital macromolecules.