Understanding Ketogenesis in Biochemistry

Ketogenesis

Production of ketone bodies from fatty acids.

Ketone Bodies

Alternative fuel source during glucose scarcity.

Fatty Acids

Primary substrates derived from triglyceride breakdown.

Acetyl-CoA

Central intermediate generated from fatty acid β-oxidation.

Mitochondria of Liver Cells

Primary site where ketogenesis occurs.

HMG-CoA Synthase

Rate-limiting enzyme catalyzing HMG-CoA formation.

HMG-CoA Lyase

Enzyme cleaving HMG-CoA into acetoacetate and acetyl-CoA.

β-Hydroxybutyrate Dehydrogenase

Converts acetoacetate to β-hydroxybutyrate.

Spontaneous Decarboxylation

Non-enzymatic conversion of acetoacetate to acetone.

Acetoacetate

First ketone body produced in ketogenesis.

β-Hydroxybutyrate

Most abundant ketone body, a hydroxy acid.

Acetone

Volatile ketone body exhaled, causing fruity breath.

Uptake by Extrahepatic Tissues

Transport of ketone bodies into non-liver cells.

Conversion to Acetyl-CoA

Process of utilizing ketone bodies for energy.

Citric Acid Cycle

Pathway where acetyl-CoA is oxidized for ATP.

Availability of Fatty Acids

Primary regulator of ketogenesis influenced by insulin.

Insulin

Hormone that inhibits lipolysis and ketogenesis.

Glucagon

Hormone that stimulates lipolysis and ketogenesis.

Malonyl-CoA Levels

Inhibits fatty acid entry into mitochondria.

NADH/NAD+ Ratio

Influences equilibrium between acetoacetate and β-hydroxybutyrate.

Alternative Fuel Source

Ketone bodies meet brain's energy needs during fasting.

Energy Source for Other Tissues

Heart and muscle utilize ketone bodies efficiently.

Regulation of Glucose Metabolism

Ketone bodies spare glucose utilization in tissues.

Diabetic Ketoacidosis (DKA)

Severe complication from uncontrolled diabetes, causing ketosis.

Alcoholic Ketoacidosis (AKA)

Ketoacidosis in chronic alcoholics due to malnutrition.

Starvation Ketoacidosis

Develops from prolonged starvation and fatty acid oxidation.

Ketogenic Diet

High-fat, low-carbohydrate diet inducing ketosis.

Formation of Acetoacetyl-CoA

Two acetyl-CoA molecules condense via thiolase.

Formation of HMG-CoA

Acetoacetyl-CoA reacts with acetyl-CoA via HMG-CoA synthase.

Cleavage of HMG-CoA

HMG-CoA is cleaved into acetoacetate and acetyl-CoA.

Reduction of Acetoacetate

Acetoacetate is reduced to β-hydroxybutyrate by NADH.

Decarboxylation of Acetoacetate

Acetoacetate spontaneously converts to acetone.