Lipids 2 Flashcards
In the beta oxidation pathway, how many fatty acid carbons does it break down at a time?
2
What are the products of beta oxidation?
Acetyl CoA, NADH, and FADH2 all sources of energy for ATP
Where does beta oxidation occur?
In the mitochondrial matrix
What does FA released from an adipocyte bind to?
Albumen
What are the 3 stages of beta oxidation?
Activation, transport and degradation
How is the fatty acid activated?
It is involved in a reaction using ATP to form fatty acyl co a in the CYTOPLASM (of the target tissue)
How does the fatty acyl co a cross the mitochondrial walls?
Fatty acyl co a diffuses across the first membrane. The carnitine shuttle is responsible for the movement of the fatty acyl co a across the second membrane- Co a component of the molecule is removed, remaining molecule then binds to carnitine and passes over the membrane with help from translocase. Carnitine is removed and fatty acyl co a is reformed
What is the effect of malonyl co a?
Inhibits the transferase enzymes, preventing further degradation of the fatty acid. Malonyl is needed for FA synthesis - therefore prevent the synthesis and degradation happening at the same time.
What is the effect of carnitine fatty acyl tranferase or carnitine palmitoyl transferase deficiency?
No beta oxidationHypoglycemia
What are the steps of degradation?
Dehydrogenation - produces FADH2Hydration - Requires H20Dehydrogenation- To produce NADHThyolysis- Cleaved to produce acetyl co a
What is the precursor of FADH2 and NADH
FADH2 = FADNADH = NAD+
What happens to acetyl co a produced?
Joins TCA cycle (citric acid cycle)
What carbon products are produced after every beta oxidation cycle?
A carbon species two carbons shorter than the original + acetyl co a
How much ATP does each of the following molecules give / use?FADH2NADHAcetyl Co A
FADH2 = 2 ATPNADH = 3 ATPAcetyl Co a = 12 ATP
Where does a preliminary beta oxidation of very long fatty acids take place?
Peroxisomes
Why is the first step (dehydrogenation) less energy efficient?
No FADH2 is produced
What happens to the FA linked to the carnitine?
Diffuses from peroxisome to mitochondria for further oxidation
What happens to acetyl co a levels during fasting / starvation?
Liver flooded with acetyl co a
What is the effect of high acetyl co a levels on pyruvate dehydrogenase?
Pyruvate dehydrogenase is inhibited reducing further acetyl co a formation?
What is the effect of high acetyl co a levels on pyruvate carboxylase?
Activates pyruvate carboxylase and therefore increases the oxaloacetate present
What does the amount of ketogenesis depend on?
The amount of acetyl co a, excess is converted into ketone bodies
What muscles use ketone bodies as an energy source?
The skeletal muscles, and the cardiac muscles
What important organ can ketone bodies also provide energy for?
The brain
Where are ketone bodies formed?
The liver, although the liver cannot actually use them!
How are ketone bodies transported from the liver?
In the blood to other tissues, they are soluble and do not need albumen or lipoprotein
What can lead to very high levels of ketone bodies in the blood?
Starvation or uncontrolled diabetes
What can result from a higher build to use ratio of etone bodies?
Ketonemia, ketonuria and acidosisfruity breath odour due to acetone
