Lipid Catabolism Flashcards
What does an increased fat intake without appropitate energy expenditure lead to?
Increased number of adipocytes
More fat in the adipocytes
What is an adipocyte?
A fat cell
What does control of energy balance depend on?
Genetic
- protein messengers, regulating appetitie
Environmental
- food abundance, fashionable foods
What is fat needed for?
As an energy source (twice as much as carb and protein)
for essential fatty acids
- some polyunsaturated fatty acids cant be made in the body, so you need to take them in your diet
For fat soluble vitamins
- ADEK - absorption of these vitamins is closely linked to that of fat
What might a deficiency in certain fatty acids result in?
Deficiencies can lead to membrane disorders, skin permeability and mitochondrial damage (reduction in energy production)
What does the uptake of vitamins need?
Associated with the uptake of fat
What are the different types of lipids?
Simple lipids (triglycerides, fatty acids) Compound lipids (phosolipids, glycolipids, lipoprotein) Steroids (cholesterol, steroid hormones)
What make up lipids?
Hydrocarbons
- hydrogen and carbon
Usually contain long chain fatty acids
Insoluble in water
What is the main energy form in adipose tissue?
Triglycerides
Describe triglycerides?
Hydrophobic
Compact - why fat can provide so much energy
Made up from 3 fatty acids and glycerol
What is the linkage between the glycerol and fatty acids?
ester link
Are fatty acids straight or branches?
Straight usually
What does saturated mean?
No double bonds
What does unsaturated mean?
One double bond
What does polyunsaturdated mean?
Several double bonds
What is configuration do the double bonds in fatty acid?
Cis
What is cis configuration?
R1 and R2 are horizontally opposite each other on the same plane
What is trans configuration?
R1 and R2 are diagonally opposite each other in the double bond
Can our body synthesis polyunsaturated fatty acids?
Not usually
How are fatty acids named?
Carboxyl group is number 1 C1 and then the rest named after that
OR
Carbon that is adjacent to the carobxyl group is alpha, and then there is an omega carbon - greek way
Describe the melting point of fatty acids. 8 carbons long, and longer?
8 Carbons or less - liquid at room temp
longer - are solid
Do double bonds higher or lower the melting point?
Lower the melting point
Describe the state of plant and animal fats?
Plant - liquid, contain unsaturated fatty acids
Animal - Solid, contain stearic acid and palmitic acid
What are the main products of lipid digestion?
Glycerol
Fatty acids
monoglycerides
Where is glycerol readily absorbed?
into epithelial cells of intestine
Where are the products of lipid digestion absorbed into?
The mucosal cells of the intestine
short and medium chain - entry portal blood
Long chain and mono - resynthesized into triglycerides (chylomicrons)
What is the chylomicron a good way for? (NOT GOOD)
a way of transporting dietary fats into the bloodstream
What happens to the chylomicrons at uncle and adipose tissue?
They are attacked and cleaved by lipoprotein lipases
What then happens to the free fatty acids broken up by the lipoprotein lipase?
They are resynthesized to triacylglycerols (in adipose tissue for storage)
Oxidised to provide energy
What is lipolysis?
The breakdown of lipids
What is fat stored as?
Adipose tissue
What breaks down the stored fats?
Hormone sensitive lipase ( e.g adrenaline - sensitive) occurs when energy is needed
What happens to the fatty acid if it needs to be used for energy?
It needs to be oxidised to generate energy
But before that it must be converted to CoA derivatives
Occurs in the cytoplasm
Requires 2 ATP
Where does further oxidation of fatty acids take place?
Further oxidase of fatty acids occurs in the mitochondiral matrix
Thus there needs to be a transport mechanism to take into mitochondria
What mechanism takes the fatty acid to be further oxidised in the mitochondrial matrix?
Carnitine shuttle
How does the carnitine shuttle work?
In the cytoplasm the fatty acids are transferred from acyl-CoA to carnitine
Acyl-carnitine transporter in inner membrane - facilitates anti port of acyl carnitine into the mictrondriaon and carnitine out
Net result - acyl CoA located in mitochondrial matrix
What is beta oxidation?
Cycle of reactions that happen in the mitochondrial matrix
What is the product of each cycle of beta oxidation?
1 Acetly-CoA
1 Fatty acyl-CoA shortened by 2 carbon atoms
1 FADH2
1 NADH + H+
How is glycerol broken down?
Activated to glycerol-3-phosphate by glycerol kinase
Where are ketone bodies formed?
In liver mitochondria
What can peripheral tissues do with ketone bodies?
Alternative way for the body to move energy around, they can covert back to acetyl-CoA which can enter the TCA cycle
What happens to oxaloacete in starvation or uncontrolled diabetes?
It is consumed for gluconeogensis
What can accumulation of ketone bodies in the blood do?
Can lead to severe acidiosis
Impairs tissue function, particularly CNS
Smell of acetone can be detected in breath
