Step 19 (Fat and Protein Catabolism for ATP Inflow)

Flashcards covering key vocabulary related to the catabolism of fat (triacylglycerols, fatty acids, glycerol) and protein (amino acids) for ATP production, including metabolic pathways, enzymes, and energy yields.

Triacylglycerols

The storage form of fat, also known as triglycerides, capable of providing 50,000-100,000 kcal of energy when stored in adipose tissue.

HSL (Hormone Sensitive Lipase)

An enzyme that stimulates the breakdown of triacylglycerols into their glycerol and fatty acid components.

Adipose tissue

Tissue where the majority of triacylglycerols (fat) are stored, providing a large energy reserve.

Intramuscular triacylglycerol

Fat stored within muscle fibers, providing an immediate energy source (2000-3000 kcal).

Lipolysis

The metabolic process of breaking down triacylglycerols into fatty acids and glycerol.

Re-esterification

The process by which fatty acids and glycerol are reassembled to form triglycerides.

Albumin

A plasma protein responsible for transporting free fatty acids (FFAs) in the blood.

Free Fatty Acids (FFAs)

Fatty acids released from adipocytes that are transported in the blood bound to plasma albumin.

Hormones influencing fat mobilization

Insulin, catecholamines (epinephrine, norepinephrine), glucagon, growth hormone (GH), and cortisol.

Acetyl CoA

A key metabolic intermediate, especially for fatty acid catabolism, that enters the Citric Acid Cycle.

Citric Acid Cycle (Krebs Cycle)

A central metabolic pathway where acetyl-CoA is completely oxidized to carbon dioxide, producing ATP, NADH, and FADH2.

β-oxidation

The process by which fatty acids are broken down in the mitochondria into two-carbon units of acetyl-CoA, one NADH, and one FADH2.

ATP yield from one glycerol molecule

19 ATP, generated through glycolysis and the citric acid cycle.

ATP yield from one 18-carbon fatty acid molecule

120 ATP, generated through β-oxidation and subsequent citric acid cycle activity.

Total ATP yield from one triglyceride (triacylglycerol) molecule

379 ATP (19 ATP from glycerol + 360 ATP from three 18-carbon fatty acids).

Protein Catabolism

The breakdown of proteins into amino acids, and further into carbon skeletons and nitrogenous waste, for energy production.

Proteolysis

The process of breaking down proteins into their constituent amino acids.

Deamination

The removal of the amino (NH2) group from an amino acid, resulting in a carbon skeleton and ammonia.

Transamination

The transfer of an amino group from an amino acid to a keto acid, forming a new amino acid and a new keto acid.

Carbon skeleton (from amino acids)

The remaining molecular structure of an amino acid after the removal of its nitrogen (amino) group, which can be used for energy or synthesis.

Glucogenic AA (Amino Acid)

Amino acids whose carbon skeletons can be converted into pyruvate or intermediates of the citric acid cycle, which can then be used for glucose synthesis (gluconeogenesis).

Ketogenic AA (Amino Acid)

Amino acids whose carbon skeletons can be converted into acetyl-CoA or acetoacetate, which can then be used for ketone body formation.

Gluconeogenesis

The metabolic pathway that results in the generation of glucose from non-carbohydrate carbon substrates such as glucogenic amino acids and glycerol.

Ketone Bodies

Alternative fuel molecules produced from the breakdown of fats or ketogenic amino acids when glucose is scarce.