Lab 3 & 4
Lipids
Main biological functions of lipids:
- Energy storage (Each gram burned of lipid produces 9 Kcal).
- Structural components of cell membranes.
- Cell signalling molecules.
- Thermal insulation.
- Electrical insulation (Covering nervous system)
Classification of lipids
| Simple lipids | Compound lipids | Derived lipids |
|---|---|---|
| FA+alcohol | FA+alcohol+additional gp | lipids from hydrolysis of the other lipid types |
| __TG__waxes | Phospholipids____Lipoproteins SulpholipidsGlycolipids | alcoholssterols (cholesterol) |
A) TG
It is glycerol esterified with 3 FA molecules that could be broken down by
Function of TG: form of lipid storage in adipose tissue; source of energy.
{{FA{{
hydrocarbon chains with COOH at the one of its ends.
| Saturated FA | Unsaturated FA | Trans FA |
|---|---|---|
| no double bonds | one or more double bonds | double bonds in trans configuration |
| - from animal sources- solid at room temp.- high melting point | - safer FA choice- low melting point-from plant oils (liquid at room temp) | -more liner-more rigid-highest melting point- |
| MUFA: oleic acidPUFA: linoleic acid, linolenic acid and arachidonic acid |
B) Phospholipids
Phospholipids have a %%glycerol molecule%% with each of its 3 carbons attached to a certain group: C1 attaches to a %%saturated FA%%, C2 attaches to an %%unsaturated FA%% and C3 attaches to the %%phosphate group (phosphoric acid).%%
- Functions of phospholipids: important component in cell membrane bilayer; in intracellular signalling.
]]Phospholipases]]
| ]]Phospholipase A1]] | ]]Phospholipase A2]] | ]]Phospholipase C]] | ]]Phospholipase D]] |
|---|---|---|---|
| which separates the saturated FA. | separates the unsaturated FA. | separates the phosphate group to give 1,2-DAG and a phosphoryl base | attacks alcohol attachment to separates entire phospholipid molecule. |
LAB 4
C) Cholesterol
complex alcohol of 4 fused rings.
- plays major risk for atherosclerosis and CAD.
Functions of cholesterol:
- converted to bile acids and bile salts by liver.
- component in cell membranes,
- when exposed to UV, could be .
Lipoprotein
Lipid-protein complexes; involved in transportation of insoluble blood lipids across bloodstream to and from tissue.
]]Lipoprotein is a complex of:]]
- Cholesterol & cholesterol esters
- Triglycerides
- Apoprotein
- Phospholipids
Classification of lipoproteins is according to ^^density^^.
Density of lipoproteins depends on its triglycerides and apoprotein content.
- Triglyceride is directly proportional to size of lipoprotein but inversely proportional to its density.
- Apoprotein is directly proportional to density.
- __Size__ of lipoprotein is inversely proportional to its density.
| Size | content | function | |
|---|---|---|---|
| 1. Chylomicrons (CM) | - largest size- lowest density | - 85-95% triglycerides - ==Apo B 48==, Apo E and Apo C | - Transports exogenous (diet) lipids -mainly TG- from intestine to adipose tissue, liver and muscle. |
| 2. VLDL | - low density | Abo B 100, Apo C, Apo E | - Transports TG from liver to muscle & adipose tissue. |
| 3. Intermediate density lipoproteins | - Intermediate between VLDL & LDL | Apo B100 & Apo E | |
| 4. LDL | Apo 100 | -could cause atherosclerosis | |
| 5. HDL | Apo A, C, D, E | cholesterol |