SAS #9: Lipid Metabolism Flashcards
is a thick semi-liquid material made up of partially digested food and gastric secretions (hydrochloric acid and several enzymes).
Chyme
The arrival of chyme from the stomach triggers in the small intestine, through the action of the hormone __________, the release of bile stored in the gallbladder.
cholecystokinin
With the help of bile, the free fatty acids and monoacylglycerols produced from hydrolysis are combined into tiny spherical droplets called _________.
micelles
A fatty acid micelle is a ________
micelle
is a lipoprotein that transports triacylglycerols from intestinal cells, via the lymphatic system, to the bloodstream.
chylomicron
is a triacylglycerol-storing cell.
adipocyte
is tissue that contains large numbers of adipocyte cells, located primarily directly beneath the skin (subcutaneous), particularly in the abdominal region, and in areas around vital organs.
Adipose tissue
storage location for the chemical energy inherent in TAGs,
Adipose tissue
provides organs with protection against physical shock.
Adipose tissue
is the hydrolysis of triacylglycerols stored in adipose tissue, followed by release into the bloodstream of the fatty acids and glycerol so produced.
Triacylglycerol mobilization
is an intermediate in both glycolysis and gluconeogenesis. It can be converted to pyruvate, then acetyl CoA, and finally carbon dioxide, or it can be used to form glucose.
Dihydroxyacetone phosphate
Oxidation of Fatty Acids:
fatty acid must be activated by boding to coenzyme A
Activation
Occur at the outer mitochondrial membrane. Reactants are the fatty acid, coenzyme A, and a molecule of ATP.
Activation
the activated fatty acid–CoA molecule refers to a random length fatty acid carbon chain that is covalently bonded to coenzyme A.
Acyl CoA
refers to a two-carbon chain covalently bonded to coenzyme A.
Acetyl CoA
Oxidation of Fatty Acids:
fatty acid must be transported into mitochondrial matrix shuttle mechanism
Transport
Oxidation of Fatty Acids:
fatty acid must be repeatedly oxidized ,cycling through a series of four reactions, to produce CoA, FADH2, and NADH
B-oxidation
lipids are ____ more efficient than carbohydrates for energy storage w/ equal no. of carbons
33%
The first step of the citric acid cycle involves the reaction between _______ and _________.
oxaloacetate and acetyl CoA.
Sufficient ________ must be present for the acetyl CoA to react with.
oxaloacetate
What happens when
oxaloacetate supplies are too low for all acetyl CoA present to be processed through the citric acid cycle?
the excess acetyl CoA is diverted to the formation of ketone bodies
Is one of three substances (acetoacetate, β-hydroxybutyrate, and acetone) produced from acetyl CoA when an excess of acetyl CoA from fatty acid degradation accumulates because of triacylglycerol-carbohydrate metabolic imbalances.
KETONE BODY
serve as sources of energy for various tissues and are very important energy sources in heart muscle and the renal cortex.
KETONE BODY
is the metabolic pathway by which ketone bodies are synthesized from acetyl CoA.
Ketogenesis
The primary site for the process of ketogenesis is ____________.
liver mitochondria.
The first ketone body to be produced is ______. This
production occurs in Step 3 of ketogenesis.
acetoacetate
steps in the process of ketogenesis:
Two acetyl CoA molecules combine to produce acetoacetyl CoA, a reversal of the last step of the b-oxidation pathway via a condensation reaction.
First condensation
steps in the process of ketogenesis:
Acetoacetyl CoA reacts with a third acetyl CoA and water to produce 3-hydroxy-3 -methylglutaryl CoA (HMG-CoA) and CoA-SH.
Second condensation.
steps in the process of ketogenesis:
HMG-CoA is cleaved to acetyl CoA and acetoacetate.
Chain cleavage.
steps in the process of ketogenesis:
Acetoacetate is reduced to β-hydroxybutyrate. The reducing agent is NADH.
Hydrogenation.
Under normal metabolic conditions (an appropriate glucose–fatty acid balance), the concentration of ketone bodies in the blood is very low about 1 mg/100 mL. Abnormal metabolic conditions, produce elevated blood ketone levels, levels 50–100 times greater than normal.
Ketosis
excess accumulation of ketone bodies in blood (20 mg/100 mL) is called At a level of 70 mg/100 mL,
Ketonemia-
the renal threshold is exceeded and ketone bodies are excreted in the urine,
Ketonuria
the overall accumulation of ketone bodies in the blood and urine. ______ is often detectable by the smell of acetone on a person’s breath; acetone is very volatile and is excreted through the lungs.
Ketosis
result of such dieting include headache, dry mouth, and sometimes acetone-smelling breath. True for fasting situation.
Mild ketosis
extremely serious ketosis that can develop to persons with uncontrolled Type 1 diabetes.
Ketoacidosis
is the metabolic pathway by which fatty acids are synthesized from acetyl CoA.
Lipogenesis
Lipogenesis or Degradation of fatty
cell cytosol
Lipogenesis
Lipogenesis: synthesis of fatty acids OR β-oxidation pathway: Degradation of fatty
mitochondrial matrix
β-oxidation pathway
Lipogenesis: synthesis of fatty acids OR β-oxidation pathway: Degradation of fatty
Enzymes are collected into a multienzyme complex called fatty acid synthase making the steps close together.
Lipogenesis
Lipogenesis: synthesis of fatty acids OR β-oxidation pathway: Degradation of fatty
Enzymes are not physically associated, so the reaction steps are independent.
β-oxidation pathway
Lipogenesis: synthesis of fatty acids OR β-oxidation pathway: Degradation of fatty
Intermediate carrier: bonded to ACP (acyl carrier protein)
Lipogenesis
Lipogenesis: synthesis of fatty acids OR β-oxidation pathway: Degradation of fatty
Intermediate carrier: CoA
β-oxidation pathway
Lipogenesis: synthesis of fatty acids OR β-oxidation pathway: Degradation of fatty
Dependent to reducing agent NADPH
Lipogenesis
Lipogenesis: synthesis of fatty acids OR β-oxidation pathway: Degradation of fatty
Dependent to oxidizing agents FAD and NAD+
β-oxidation pathway
Lipogenesis: synthesis of fatty acids OR β-oxidation pathway: Degradation of fatty
acetyl CoA is used to form malonyl ACP, which becomes the carrier of the two carbon units
Lipogenesis
Lipogenesis: synthesis of fatty acids OR β-oxidation pathway: Degradation of fatty
CoA derivatives are involved in all steps
β-oxidation pathway
the starting material for lipogenesis
Acetyl CoA
