Fat Metabolism Flashcards
What is the main energy storage in living organisms?
Triacylglycerol
Triacylglycerol serves as the primary form of energy storage in organisms.
What is cholesterol important for?
Constituent of cell membranes and precursor to steroid hormones and bile salts
Cholesterol plays crucial roles in cellular structure and hormone synthesis.
What are glycolipids and phospholipids important for?
Synthesis of cell membranes
These lipids are essential components of cellular membranes.
How are triacylglycerols transported in the blood?
Bound to lipoproteins
This binding allows insoluble lipids to remain in an aqueous environment.
What happens to triacylglycerols in adipose tissues and skeletal muscles?
Hydrolysed into glycerol and free fatty acids
This process allows tissues to utilize fatty acids for energy.
Where is glycerol transferred after hydrolysis of triacylglycerols?
To the liver and kidney
Glycerol participates in gluconeogenesis.
What is the structure of fatty acids?
Long hydrocarbon chains with a terminal carboxylic group
The structure of fatty acids influences their properties.
What does the synthesis of fatty acids involve?
Condensation of two-carbon units (acetyl CoA)
This process occurs in a series of reactions facilitated by the fatty acid synthase complex.
Where does fatty acid synthesis take place?
In the cytosol
This is distinct from fatty acid oxidation, which occurs in mitochondria.
What is the role of NADPH in fatty acid synthesis?
Acts as a reducing agent
NADPH is crucial for the reduction reactions in fatty acid synthesis.
What is the rate limiting step in fatty acid synthesis?
Carboxylation of acetyl-CoA to malonyl CoA
This step is mediated by acetyl-CoA carboxylase (ACC).
What happens to acetyl-CoA in the cytosol?
It is transferred from mitochondria in the form of citrate
Acetyl-CoA cannot cross the mitochondrial membrane directly.
What is the inactive state of acetyl-CoA carboxylase (ACC)?
Dimer
The active state of ACC is a polymer, which is induced by citrate.
What does the fatty acid synthase complex (FAS) produce?
Saturated fatty acids from acetyl-CoA and malonyl-CoA
FAS facilitates the series of reactions in fatty acid synthesis.
What is required for introducing double bonds to fatty acids?
Molecular oxygen and electrons
This process is known as desaturation.
What is the process of fatty acid oxidation?
β-oxidation
Fatty acids are oxidized into acetyl-CoA during this process.
Where does fatty acid oxidation occur?
In the mitochondria
This is separate from where fatty acid synthesis occurs.
What are the requirements for β-oxidation?
Activated acyl-CoA molecules, NAD+, FAD
These components are necessary for the oxidation process.
What is the first step of β-oxidation?
Fatty acid activation
This step requires ATP and is mediated by acyl-CoA synthetase.
What enzyme catalyzes the transfer of the acyl group from CoA to carnitine?
Carnitine palmitoyltransferase I (CPT-I)
This enzyme is located in the outer mitochondrial membrane.
What does β-oxidation produce in each cycle?
1 NADH, 1 FADH2, and 1 molecule of acetyl-CoA
These products contribute to ATP synthesis via oxidative phosphorylation.
What occurs during the oxidation of unsaturated fatty acids?
Requires an additional enzyme (isomerase)
This enzyme converts the 3-trans derivative to the 2-trans derivative.
What are ketone bodies produced from?
Excess acetyl-CoA
Ketone bodies serve as an energy source for peripheral tissues.
What condition can lead to ketoacidosis?
Uncontrolled diabetes
This results from excess ketone body production, leading to acetone breath.
