Fatty acids Flashcards
When does fatty acid synthesis occur?
Abundance of energy
High ATP lvls inhibit Krebs cycle
Lead build up of acetyl coA
Where does synthesis of FA occur?
Cytosol of cell
What can’t acetyl coA cross?
Mitochondrial membranes
Outline the citrate shuffle?
Oxaloacetate binds with acetyl coA to produce citrate
Citrate can cross mitochondrial membrane into cytosol
Citrate ligase converts citrate back to oxaloacetate
Oxaloacetate broken down into pyruvate and acetyl coA
Pyruvate recycled back into mitochondria and converted into oxaloacetate and re-enters the Krebs Cycle
The acetyl coA is the converted into fatty acids
Why is citrate shuffle needed?
To cross mitochondrial membrane
What happens to pyruvate?
Pyruvate recycled back into mitochondria and converted into oxaloacetate and re-enters the Krebs Cycle
What happens to acetyl coA?
Converted into fatty acids
Give two examples of FA?
Linoleic acid (18C)
Oleic acid (18C)
Palmitic acid (16C)
Arachidonic acid (20C)
Draw process of fatty acid synthesis?
What is metabolism of fatty acids?
Break down fatty acids to produce energy
When does fatty acid metabolism occur?
Occurs response to: decreased blood glucose
high glucagon
Can fatty acids diffuse through mitochondrial membrane?
FA longer than 12 C can’t diffuse through mitochondrial membrane- need transport
Define FA?
Long acyl coA chains
How many carbons do dietary fatty acids have?
Tend more than 12
What process converts and reforms acyl coA chains?
Carnitine shuffle
Outline carnitine shuffle?
On outer mitochondrial membrane- Acyl coA converted to acyl carnitine (by carnitine acyltransferase 1 –CAT1)
Co A is recycled
On interior side membrane- Acyl carnitine is reformed to acyl coA (by carnitine acyltransferase 2 – CAT2)
Carnitine is recycled through the outer membrane
What converts Acyl coA to acyl carnitine?
Carnitine acyltransferase 1 (CAT1)
What reforms acyl carnitine to acyl coA?
Carnitine acyltransferase 2 (CAT2)
What occurs once acyl coA has crossed the membrane?
Oxidised- beta oxidation
What occurs in beta oxidation?
Sequential removal of 2 carbon units by oxidation
Second carbon cleaved
What undergoes oxidative phosphorylation?
FADH2, NAD
What happens to acetyl coA?
Re-enters Krebs cycle
What are products of beta oxidation?
1 NADH
1 FADH2
1 Acetyl coA
What occurs when there’s a shortage of carbohydrates?
Increased production ketone bodies
Why is there increased production of ketones?
Increased beta oxidation
Increased production acetyl coA
What muscles can ketones be used?
Cardiac and skeletal
Give an example of ketone bodies?
Acetone, acetoacetate
What disease occurs when there is a disruption ketone bodies?
Insulin-dependent diabetes mellitus
Side effects of increased ketone lvls?
Diabetic ketoacidosis
Impair O2 binding to Hb- therefore patient hyperventilates
Low pH, pCO2, HCO3-
High PO2
How are ketones synthesised?
2 acetyl coA’s converted by thiolase to acetoacetyl coA
Converted to acetoacetate
Enter blood or converted to beta hydroxybutyrate
Acetoacetate and beta hydroxybutyrate oxidised as fuels in tissues
When is the production of beta hydroxybutyrate high?
Level of glycogen is high
Draw synthesis ketones
