Biochemistry of Lipids Flashcards
What are the functions of lipids in the body?
- Essential nutrient (fatty acids, development of brain tissue, formation of non essential fatty acids)
- energy storage
- carrier of essential vitamins (A,D,E and K)
- Insulation (thermal) and cushioning (mechanical) of body organs
- membrane structure and function
What is the difference between saturated and unsaturated fatty acids?
Saturated - all bonds are single bonds
Unsaturated - some of the bonds are double bonds
What is the difference between cis and trans unsaturated fatty acids?
Cis - hydrogen atoms on the double-bonded carbon atoms are on the same side
Trans - hydrogen atoms on the double-bonded atoms are on opposite sides
What fatty acids can the body not synthesise and what are their sources?
Linoleic acid (omega-6) and alpha-linolenic acid (omega-3) - The essential fatty acids
Oily fish - Salmon, Mackerel, Sardines, Herring
Plant sources - olive, corn, flaxseed/primrose oil.
What are the functions of essential fatty acids and what are they converted to in the body?
Metabolism, formation of cell walls and tissue repair.
Alpha-linolenic acid (Omega 3) -> EPA (nerve function)
Linoleic acid (Omega 6) -> arachidonic acid -> prostaglandins etc.
What are the functions of cholesterol?
- stabilises cell membranes
- precursor to many steroid hormones
- metabolised to bile acids in liver
- converted in skin to a vitamin D precursor
- Deposited in the atheromatous plaque that causes atherosclerosis
What are the sources of cholesterol? (Apart from endogenously by the liver)
Animal foods
When are there problems with cholesterol?
- Body makes too much LDL
- intake exceeds body’s disposal
How are fatty acids and lipids transported in the blood?
Fatty acids - albumin
Lipids - lipoproteins (water insoluble core of lipids covers by amphiphilic lipids + proteins)
What is the function of LDL?
To deliver cholesterol to tissues for the synthesis and repair of cell membranes, by passive endocytosis and receptor mediated uptake.
What is the function of HDL?
Removes excess cholesterol from membranes and other lipoprotein particles and converts it into cholesteryl ester (then processed for re-use by liver)
What is the total cholesterol level a predictor of?
Cardiovascular disease (CVD) events
What is HDL inversely related to?
CVD risk
What non-HDL cholesterol level?
Total cholesterol minus HDL cholesterol
What does the ratio of total cholesterol to HDL take into account?
The risks associated with both types of cholesterol, used to estimate CVD risk.
