Fatty Acid Metabolism Overview

A metabolic process that breaks down fatty acids to produce energy.

Fatty acids are classified by their carbon chain length: short (2-4C), medium (5-11C), long (12-22C), and very long (>22C).

The process of attaching Coenzyme A (CoA) to a fatty acid to allow it to enter the mitochondria.

A transport system that moves fatty acyl-CoA molecules across the mitochondrial membranes.

An enzyme involved in the first step of beta-oxidation, which oxidizes fatty acyl-CoA and produces FADH2.

The inner compartment of mitochondria where beta-oxidation and the citric acid cycle occur.

A crucial molecule that enters the citric acid cycle to generate energy.

Creates a double bond between the beta and alpha carbons of a fatty acid chain.

Significantly affects beta-oxidation because FAD is the first cofactor needed in the process.

Adds a water molecule (hydration) across the double bond in the fatty acid chain.

Oxidizes the hydroxyl group (OH) to a carbonyl group (C=O) in the fatty acid chain.

The coenzyme NAD+ is a crucial part of the 3-hydroxyacyl-CoA dehydrogenase step.

Cleaves the bond between alpha and beta carbons, releasing acetyl-CoA.

Involves two oxidations, one hydration, and one thiolysis to oxidize the fatty acid.

Fatty acids need to be converted to acyl-CoA to be transported and used in beta-oxidation, and to avoid emulsifying the cell membrane.

Transports long-chain fatty acyl-CoA into the mitochondria for beta-oxidation.

Activates long-chain fatty acids (LCFAs) in the cytoplasm by attaching CoA.

Translocates acyl-carnitine across the outer mitochondrial membrane.

Converts acyl-carnitine back to acyl-CoA within the mitochondrial matrix.

Allows carnitine to return to the cytosol (outside of the mitochondria)

Beta-oxidation in unsaturated fatty acids differs from saturated fatty acids in that isomerases reposition double bonds before hydration and subsequent reactions. No FADH2 is produced in first step as a dehydrogenase isn't involved.

Interruption of the process that breaks down fatty acids for energy production.

The breakdown of long-chain fatty acids, requiring the carnitine shuttle for transport to the mitochondria.

Peroxisomes handle the preliminary beta-oxidation of very long chain fatty acids, shortening them to medium chains, which then proceed to further breakdown in mitochondria.

Peroxisomes are the sites where plasmalogen (ether lipid) is synthesised, supporting cell membrane function.

A process that transports long-chain fatty acids into the mitochondria.

Peroxisomes participate in the alpha-oxidation of phytanic acid. This is an important breakdown pathway for specific fatty acids.

A metabolic process that breaks down fatty acids into acetyl-CoA, generating energy.

During fasting/starvation, the body shifts from using glucose (fed state) to using stored fats and proteins to provide energy.

A molecule that's a crucial intermediate in metabolism, used for energy production.

Acetyl-CoA, FADH2, NADH, and a shortened fatty acyl-CoA.

Unsaturated fatty acids require isomerases to convert cis to trans bonds, skipping the initial FADH2 producing step with acyl-CoA dehydrogenase as it already has a double bond, unlike saturated fatty acids.

Fatty acyl-CoA, CoA, water, FAD, and NAD+.

A genetic condition where the enzyme for breaking down long-chain fatty acids is deficient.

A genetic condition where the enzyme breaking down medium-chain fatty acids is deficient.

A genetic condition where the enzyme for breaking down short-chain fatty acids is deficient.

Sudden Infant Death Syndrome.

Glucose is the primary energy source for the brain, red blood cells (RBCs), kidneys, and lens epithelial cells.

Fatty acids are the primary energy source for heart, lung, liver, intestines, and skeletal muscle.

In starvation, the body adapts by shifting to ketone bodies as a fuel source for the brain since glucose is not available in sufficient amounts and to prevent protein degradation.

Synthesis of ketone bodies occurs in the liver mitochondria to utilize fatty acids.

The primary ketone bodies are beta-hydroxybutyrate and acetoacetate, with small amounts of acetone.

HMG-CoA synthase is the enzyme that controls the rate of ketone synthesis, catalyzing the condensation reaction.

Ketone bodies provide an alternative energy source for cells when glucose is unavailable, important for the brain during starvation or diabetes.

Ketone body breakdown (ketolysis) occurs in the mitochondrial matrix across various tissues, not just the liver.

Acetoacetate is the primary ketone body produced by the liver during fasting or prolonged starvation.

Acetoacetate is formed from HMG-CoA via HMG-CoA lyase.

Acetoacetate can be converted to beta-hydroxybutyrate and acetone.

Beta-hydroxybutyrate is the most abundant ketone body during fasting or starvation.

Beta-hydroxybutyrate is formed by the reduction of acetoacetate.

Beta-hydroxybutyrate is a more efficient energy transport molecule than acetoacetate.

Peripheral tissues use beta-hydroxybutyrate for ATP production after converting it to acetoacetate.

Acetone is a non-metabolizable ketone body formed by the spontaneous decarboxylation of acetoacetate.

Acetone is exhaled in breath and doesn't provide usable energy.

The ratio of beta-hydroxybutyrate to acetoacetate in the blood depends on the NADH/NAD+ concentration in liver mitochondria.

Beta-hydroxybutyrate dehydrogenase is the enzyme that converts acetoacetate to beta-hydroxybutyrate and vice versa.

Thiophorase converts acetoacetate to acetoacetyl-CoA, using succinyl-CoA in peripheral tissues to generate ATP.

Ketone body synthesis is primarily regulated by substrate availability (e.g. fatty acids).