Exam questions

Structural & functional differences between different types of lipids

Lipids are hydrophobic molecules.

Triglycerides are an energy storage lipid

• Composed of glycerol joined to 3 fatty acid molecules.

• By condensation reaction

• Forming ester bonds

• They are transported in the blood in HDLs or LDLs

• If any of the fatty acids contains 1 or more carbon-carbon double bonds it is an unsaturated fat

Triglycerides can be hydrolysed to release the fatty acid chains, which can be further broken down into Acetyl-CoA molecules that can be used in respiration.

Saturated fatty acids are straight molecules, can pack more closely together & are associated with high risk of CVD

Cholesterol is a planar molecule found in cell membranes

Describe what lipoproteins are & normal role of HDL & LDL

• Lipoproteins are triglycerides surrounded by a layer of phospholipid, protein & cholesterol.

• Lipoproteins are how triglycerides are transported in the blood.

• Excess energy in diet is converted to LDLs by liver for fat to be transported to adipose tissues for long term storage.

• LDLs contain more saturated fats, more cholesterol & less protein.

• When energy stores are used up, fat is released by adipose back into the blood as HDL

• HDLs contain more unsaturated fats, less cholesterol & more protein.

Describe the role of lipoproteins in CVD

• The ratio of HDL to LDL is correlated to CVD

• A low HDL : LDL is a risk factor for CVD

• Because WBC can absorb their saturated fats & cholesterol to become foam cells.

• A high HDL : LDL is thought to have protective effects against CVD

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