Lipid Metabolism during Fasting

Breakdown of fats (lipolysis) is increased during fasting to provide energy.

Insulin normally inhibits lipolysis (fat breakdown), while in sepsis, insulin resistance overrides this inhibition, allowing lipolysis.

Breakdown of fatty acids (Beta-oxidation) is impaired during sepsis, leading to accumulation of FFAs in organs (and blood).

PPAR-α, a transcription factor, is upregulated in fasting, stimulating fat breakdown.

In sepsis, PPAR-α is downregulated, preventing adequate fat breakdown—opposite to fasting.

Peroxisomes are organelles that break down very long-chain fatty acids (VLCFAs).

Sepsis causes a shortage of energy due to impaired fatty acid breakdown, resulting in potential organ damage.

VLCFAs are broken down to MCFA's, then sent to mitochondria for complete breakdown into CO2 and water in animals; this is exclusively done in peroxisomes in plants & yeast.

Organelles that break down harmful substances like hydrogen peroxide in cells.

Peroxisomes convert hydrogen peroxide to water, making it harmless.

Peroxisomes import proteins from the cytosol needed for their reproduction.

Specific amino acid sequences that direct proteins to peroxisomes.

Detoxify alcohol and harmful compounds in liver cells.

Peroxisomes help create phospholipids used in membrane formation.

Older name for organelles now referred to as peroxisomes and lysosomes.

Another type of microbody, formed in the Golgi complex, distinct from peroxisomes through origin.

An autosomal recessive disorder caused by mutations in genes encoding peroxins, proteins responsible for peroxisome assembly.

Proteins needed for building and maintaining peroxisomes.

Genes that code for peroxins.

Very long chain fatty acids, usually broken down by peroxisomes.

Branched chain fatty acids, usually broken down by peroxisomes.

The division of a peroxisome into two daughter peroxisomes.

The process of proteins being brought inside and inserted in the peroxisome membrane.

Fatty acid oxidation occurs in four sequential steps, each catalyzed by a different enzyme, each step generates energy-carrying molecules, and shortens the fatty acid by two carbons.

The first step of beta-oxidation, involving oxidation, which forms a trans intermediate.

This step in beta-oxidation is similar to a citric acid cycle reaction (fumarase).

This step in beta-oxidation mirrors another citric acid cycle reaction (malate dehydrogenase).

The final step in beta-oxidation involves the enzyme 'thiolase' and generates Acetyl-CoA.

Genetic conditions affecting peroxisomes, organelles crucial for various metabolic processes.

Distinctive facial features like high forehead, frontal bossing, small face seen in peroxisomal disorders.

Decreased muscle tone, often a symptom of certain disorders.

Reduced levels of myelin, a protective layer around nerve fibers in the central nervous system.

The breakdown of fatty acids to produce energy (ATP).

A specific metabolic pathway for breaking down fatty acids, 2 carbons at a time.

The preparation step before fatty acid oxidation, requiring energy.