Fat Storage and Transport Flashcards
What are carbohydrates stored as?
What is our bodies long term fat store?
Glycogen
Triglyceride
What 2 tissues is fat released from?
What two tissues can be utilised at?
Small intestine and liver
Muscle and adipose tissue
Where does fatty acid synthesis occur?
What is it stimulated by?
Cytosol of liver cells
Insulin
What two things are fatty acids formed from?
Where does one of these come from?
Acetyl - CoA and NADPH
Acetyl - CoA mainly comes from carbohydrates via the glycolytic pathway.
What is the first step in fatty acid synthesis?
Acetyl CoA is converted to malonyl CoA. This is catalysed by acetyl CoA carboxylase (activated by insulin).
Malonly CoA signifies the FED state as it means that the digested food may be turning into fatty acids.
What inhibition is vital after fatty acid synthesis?
Malonyl CoA inhibits carnitine transferase and so inhibits the entry of fatty acids into the mitochondrion to prevent the fatty acid being oxidised.
After acetyl CoA is converted to malonyl CoA, how does fatty synthesis occur?
Acetyl CoA (2 carbons) and malonyl CoA (3 carbons) combine. One carbon is released as carbon dioxide (3-1 carbons added)
What type of enzyme is a fatty acid synthetase?
A dimer
What enzyme needs to be added to glycerol and 3 fatty acids to make a triglyceride?
Glycerol phosphate
What needs to be added to a triglyceride for it to move out a cell?
Apoproteins
What is the structure of a lipoprotein?
What is their main job?
It has an inner core consisting of triglycerides and cholesterol esters.
It has an outer shell which is a single layer of phospholipids, cholesterol and apoproteins.
Main job is for transportation
Give 3 points on apoproteins
- They have a structural role (hydrophilic groups on surface).
- Recognised by receptors
- Activates certain enzymes in lipid metabolism
Give 3 classes of lipoproteins
- Chylomicrons - they carry the triglycerides from the small intestine
- LDL - mainly carries cholesterol
- HDL - considered good as they carry fatty acids to the liver for excretion
Explain the transport of triglycerides in the capillary to the liver (exogenous fat going from small intestine to liver)
TAG initially has one apoprotein attached.
TAG picks up 2 more apoproteins which provided from HDL. This enters the capillary and lipase is here. This breaks down the triglyceride into fatty acids which enter adipose tissue to be stored as TAG and glycerol which is transported to the liver.
Explain the transport of endogenous fat (from the liver to the peripheral tissue)
Glycerol is transported to the liver from the capillary. TAG leaves the capillary and attaches to apoproteins and this can then enter the liver. the liver has a B-100 receptor which is one of the apoproteins on the TAG. It can also be taken up by peripheral tissue due to the tissue have this B-100 receptor also.