ch 24 Lipid and Amino Acid Metabolism Overview

Triglycerides

Hydrolyzed to glycerol and fatty acids during digestion.

Phosphoglycerides

Hydrolyzed to their component substances in digestion.

Chylomicrons

Lipoprotein aggregates formed for lipid transport.

VLDL

Very low density lipoprotein, high lipid concentration.

LDL

Low density lipoprotein, associated with cholesterol transport.

HDL

High density lipoprotein, helps remove cholesterol from blood.

Fat Mobilization

Hydrolysis of triglycerides releasing fatty acids into blood.

Glycerol Metabolism

Converted to dihydroxyacetone phosphate for glycolysis.

Fatty Acyl CoA

Activated form of fatty acids for catabolism.

Acyl CoA Synthetase

Enzyme catalyzing fatty acid activation to acyl CoA.

ATP Hydrolysis

Provides energy for fatty acid activation process.

β-Oxidation

Metabolic pathway for fatty acid catabolism.

Ketone Bodies

Produced during fatty acid oxidation, includes acetoacetate.

Urea Cycle

Pathway converting ammonia to urea for excretion.

Transamination

Process of transferring amino groups between amino acids.

Deamination

Removal of an amino group from an amino acid.

Amino Acid Pool

Collection of amino acids available for protein synthesis.

Gluconeogenesis

Synthesis of glucose from non-carbohydrate sources.

Energy Production

Amino acids can be converted to ATP.

Triglyceride Resynthesis

Occurs in intestinal mucosa after lipid absorption.

Blood Lipid Behavior

Increases post-meal, normalizes through fat storage.

Fatty Acid Energy Source

Used when glycogen stores are depleted.

Blood-Brain Barrier

Prevents direct nutrient access to brain cells.

Phosphoglycerides

Hydrolyzed to component substances in lipid digestion.

Chylomicrons

Lipoprotein aggregates transporting insoluble lipids.

Lipoproteins

Complexes of lipids and proteins for lipid transport.

LDL

Low density lipoprotein, carries cholesterol to tissues.

HDL

High density lipoprotein, removes cholesterol from tissues.

Fat Mobilization

Hydrolysis of triglycerides for energy production.

Glycerol

Converted to dihydroxyacetone phosphate for glycolysis.

Acyl CoA Synthetase

Enzyme converting fatty acids to fatty acyl CoA.

ATP Hydrolysis

Provides energy for fatty acid activation.

β-Oxidation

Pathway for fatty acid catabolism into acetyl-CoA.

Ketone Bodies

Produced during fat metabolism under certain conditions.

Urea Cycle

Process converting ammonia to urea for excretion.

Transamination

Transfer of amino group between amino acids.

Deamination

Removal of amino group, producing ammonia.

Energy Production

Amino acids can be used for ATP synthesis.

Triglyceride Synthesis

Amino acids can synthesize triglycerides for storage.

Gluconeogenesis

Process of synthesizing glucose from non-carbohydrates.

Blood Lipid Behavior

Increases after meals, normalizes through storage.

Plasma Lipid Concentration

Peaks 4-6 hours post meal, then drops.

Amino Acid Pool

Source of amino acids for protein synthesis.

Fatty acyl-CoA

Substrate for the initial β-oxidation step.

β-Oxidation

Metabolic process breaking down fatty acids.

Substrate

Molecule upon which an enzyme acts.

Final Step

Last phase producing fatty acyl-CoA.

Next Round

Subsequent cycle of β-oxidation process.

β-oxidation

Process of fatty acid degradation in mitochondria.

Acetyl-CoA

Two-carbon molecule produced from fatty acid breakdown.

Fatty Acyl CoA

Activated fatty acid form entering β-oxidation.

NADH

Electron carrier produced during fatty acid oxidation.

FADH2

Another electron carrier generated in β-oxidation.

Fatty Acid Spiral

Pathway for sequential degradation of fatty acids.

Stearic Acid

C18 fatty acid used in oxidation examples.

Activation Step

Conversion of fatty acid to fatty acyl CoA.

ATP Yield from Acetyl-CoA

10 ATP produced per acetyl-CoA in citric acid cycle.

ATP Yield from NADH

2.5 ATP produced per NADH in electron transport.

ATP Yield from FADH2

1.5 ATP produced per FADH2 in electron transport.

Ketonemia

Elevated ketone bodies in blood above 20 mg/100 mL.

Ketonuria

Presence of ketone bodies in urine above 70 mg/100 mL.

Acetone Breath

Detection of acetone in breath indicating ketosis.

Ketosis

Condition with ketonemia, ketonuria, and acetone breath.

Ketoacidosis

Condition with low blood pH due to ketones.

Insulin Treatment

Used to manage diabetes-related ketosis.

Oxaloacetate

Intermediate that combines with acetyl CoA for transport.

Citrate

Formed from acetyl CoA and oxaloacetate in cytoplasm.

Butyryl CoA

Four-carbon chain that undergoes β-oxidation.

Total ATP from Stearic Acid

120 ATP produced from complete oxidation of stearic acid.

Energy Density of Fatty Acids

Lipids contain more than twice the energy of carbohydrates.

Fatty Acid Synthesis Location

Occurs in the cytoplasm, opposite of degradation.

Fatty Acid Degradation Location

Occurs in mitochondria, opposite of synthesis.

Fatty Acyl-CoA

Substrate for β-oxidation in mitochondria.

β-Oxidation

Process degrading fatty acids into acetyl-CoA.

Acetyl-CoA

End product of fatty acid degradation.

NADH

Electron carrier produced in β-oxidation.

FADH2

Another electron carrier generated during oxidation.

Fatty Acid Spiral

Pathway for sequential fatty acid degradation.

Activation Step

Conversion of fatty acid to fatty acyl-CoA.

Stearic Acid

C18 fatty acid undergoing β-oxidation.

ATP Yield

Total ATP from stearic acid oxidation is 120.

Oxaloacetate

Intermediate that regulates citric acid cycle activity.

Ketonemia

Elevated ketone bodies in blood (>20 mg/100 mL).

Ketonuria

Presence of ketone bodies in urine.

Acetone Breath

Detection of acetone in breath.

Ketoacidosis

Low blood pH due to high ketone levels.

Citrate

Transport form of acetyl CoA to cytoplasm.

ATP Multipliers

10 ATP per acetyl CoA, 2.5 per NADH, 1.5 per FADH2.

Butyryl CoA

Four-carbon chain processed in β-oxidation.

Energy Density

Lipids provide more energy than carbohydrates.

Fatty Acid Synthesis

Occurs in cytoplasm, opposite of degradation.

Hydrolysis of ATP

Provides energy for fatty acid activation.

Total ATP from NADH

20 ATP from 8 NADH produced.

Total ATP from FADH2

12 ATP from 8 FADH2 produced.

Malonyl-ACP

Carries carbon pairs in fatty acid synthesis.

Fatty Acid Synthetase System

Multienzyme complex for fatty acid synthesis.

Acyl Carrier Protein (ACP)

Binds fatty acyl chains during synthesis.

Triglycerides

Form of fat stored in adipose tissues.

Adipose Tissues

Body tissue that stores fat.

Liver Role

Modifies body fats through chain alterations.