Biochemistry of Fat Metabolism

<p>They provide an alternative energy source for tissues (C)</p> Signup and view all the answers

<p>Cholesterol (B)</p> Signup and view all the answers

<p>Triglycerides yield more energy per gram. (D)</p> Signup and view all the answers

<p>A saturated fatty acid. (D)</p> Signup and view all the answers

<p>It enters glycolysis and is converted to pyruvate. (D)</p> Signup and view all the answers

<p>Lipase. (D)</p> Signup and view all the answers

<p>In the mitochondrial matrix. (D)</p> Signup and view all the answers

<p>To form thioester bonds with fatty acids. (C)</p> Signup and view all the answers

<p>Via the carnitine shuttle. (B)</p> Signup and view all the answers

<p>Gluconeogenesis. (C)</p> Signup and view all the answers

<p>NADH and FADH2 from electron carriers. (A)</p> Signup and view all the answers

<p>To hydrolyze diacylglycerol to free fatty acids. (C)</p> Signup and view all the answers

<p>Excess Acetyl CoA (C)</p> Signup and view all the answers

<p>Most tissues, excluding liver (B)</p> Signup and view all the answers

<p>It lacks the necessary enzymes (A)</p> Signup and view all the answers

<p>Glucose (C)</p> Signup and view all the answers

<p>They are carried by albumin (C)</p> Signup and view all the answers

<p>Propionyl-CoA (C)</p> Signup and view all the answers

<p>Oxidation, oxidation, decarboxylation (D)</p> Signup and view all the answers

<p>Accumulation of lipid droplets in the mitochondrial matrix of liver cells (C)</p> Signup and view all the answers

<p>Facilitates the transport of fatty acyl-carnitine (D)</p> Signup and view all the answers

<p>Removal of 2 hydrogen atoms (A)</p> Signup and view all the answers

<p>Produces a carbon chain that is 2 carbons shorter (A)</p> Signup and view all the answers

<p>Converts fatty acyl-carnitine back into fatty acyl-CoA (B)</p> Signup and view all the answers

<p>Acetyl-CoA (D)</p> Signup and view all the answers

<p>Starvation and Type I diabetes (C)</p> Signup and view all the answers

<p>NAD+ (C)</p> Signup and view all the answers

<p>One NADH and one FADH2 (D)</p> Signup and view all the answers

<p>It generates ATP equivalent to yielding Acetyl-CoA (D)</p> Signup and view all the answers

<p>It is converted into succinyl-CoA for the TCA cycle (D)</p> Signup and view all the answers

<p>Enoyl-CoA hydratase (D)</p> Signup and view all the answers

<p>Carnitine shuttle activity (B)</p> Signup and view all the answers

<p>Activation to fatty acyl-CoA (A)</p> Signup and view all the answers

<p>It becomes shorter by 2 carbons (B)</p> Signup and view all the answers

Triglycerides are the primary long-term energy storage form in the body, providing a rich source of energy for various physiological processes.

Adipose tissue lipase is an enzyme that breaks down triglycerides into glycerol and free fatty acids, releasing stored energy for use by the body.

Fatty acids are activated by converting them into their CoA esters, a process that prepares them for transport into mitochondria, the powerhouses of cells.

The carnitine shuttle system facilitates the transport of activated fatty acids across the mitochondrial membrane, allowing them to enter the beta-oxidation pathway for energy production.

Beta-oxidation is a metabolic pathway that breaks down fatty acids into acetyl-CoA, NADH, and FADH2. These molecules then enter the citric acid cycle and electron transport chain to generate ATP, the energy currency of the body.

Triglycerides (TG) are the primary storage form of fat in the body. They are stored as large fat droplets within fat cells (adipocytes).

A 70 kg adult typically stores around 11 kg of fat as triglycerides. This highlights the body's significant capacity for fat storage.

Triglycerides are more efficient at energy storage than glycogen. 1 gram of fat yields 38 kJ of energy, compared to 21 kJ for 1 gram of protein.

Triglycerides are composed of a glycerol molecule linked to three fatty acid chains. Glycerol is a small, water-soluble molecule, while fatty acids are long, hydrophobic chains.

Common fatty acids found in triglycerides include palmitic acid (C16:0), stearic acid (C18:0), and oleic acid (C18:1). The numbers indicate the number of carbons and the presence of double bonds in the chain.

When the body needs energy, stored triglycerides are broken down in adipocytes through a process called lipolysis. This involves enzymes called lipases, which hydrolyze the ester bonds between glycerol and fatty acids.

Lipolysis is activated by hormones like adrenaline and glucagon, which signal a need for energy. This process releases free fatty acids and glycerol into the bloodstream.

Free fatty acids are transported in the bloodstream bound to albumin, a protein that prevents them from aggregating. They can then reach various tissues to be used as fuel.

Glycerol, a water-soluble byproduct of lipolysis, can be taken up by most tissues. It enters glycolysis and can be converted to pyruvate or glucose, depending on the body's needs.

Fatty acids are broken down through a process called beta-oxidation, which occurs in the mitochondria. This process involves a series of enzymatic reactions that remove two-carbon units (acetyl-CoA) from the fatty acid chain.

The process of transporting fatty acids into mitochondria, where they are broken down for energy.

An enzyme that attaches a carnitine molecule to a fatty acid, forming fatty acyl-carnitine.

A molecule that helps transport fatty acids across the inner mitochondrial membrane.

An enzyme that removes carnitine from fatty acyl-carnitine, regenerating fatty acyl-CoA.

The process of breaking down fatty acids into acetyl-CoA, NADH, and FADH2.

The first step of beta-oxidation, removing two hydrogen atoms from a fatty acyl-CoA.

Adding a water molecule across a double bond in the fatty acid chain.

The third step in beta-oxidation, removing two hydrogen atoms from the hydroxyl group in a hydroxyacyl-CoA.

The final step of beta-oxidation, cleaving a 4-carbon unit from the fatty acid chain, producing acetyl-CoA and a shortened fatty acyl-CoA.

The cyclic metabolic pathway that oxidizes acetyl-CoA to produce energy.

A small molecule produced during beta-oxidation, which enters the Krebs cycle to produce ATP.

The process of producing ketone bodies from fatty acids.

A group of molecules produced during ketogenesis, used as an alternative energy source by the body.

A metabolic pathway that breaks down a 3-carbon molecule (propionyl-CoA) produced from the breakdown of odd-numbered fatty acids.

A molecule produced by the propionyl-CoA metabolism pathway, which enters the TCA cycle to produce ATP.

When there is excess Acetyl-CoA, it is converted to ketone bodies in the liver. These ketone bodies, acetoacetate and β-hydroxybutyrate, are then released into the bloodstream, providing energy to most cells.

Ketone bodies are a source of energy that can be utilized by most tissues, but not all. They are particularly important during starvation or when glucose levels are low.

The liver cannot utilize ketone bodies for energy because it lacks the necessary enzyme, succinyl CoA transferase. This enzyme is essential for converting ketone bodies into usable energy.

The brain primarily utilizes glucose for energy and can only use small amounts of ketone bodies. It lacks the enzymes necessary to fully utilize fatty acids as an energy source.

Lipids have three primary functions: 1. Components of membranes: They form the structural basis of cell membranes, acting as barriers and regulating what enters and leaves the cell. 2. Precursor for steroid hormones: These hormones play crucial roles in various bodily functions, including reproduction and regulating metabolism. 3. Long-term fuel storage: Lipids serve as a major energy reserve, providing a concentrated source of energy that can be accessed when needed.

Fatty acids with an odd number of carbons undergo β-oxidation until three carbons remain. This three-carbon unit (propionyl-CoA) is then converted to succinyl-CoA. This molecule is an intermediate of the citric acid cycle and can ultimately be used to produce ATP.

Beta-oxidation is a cyclical process that breaks down fatty acids into acetyl-CoA, NADH, and FADH2. This occurs in mitochondria, and these molecules then enter the citric acid cycle and electron transport chain, ultimately generating ATP. This sequence involves repeated steps of oxidation, hydration, and oxidation.