Topic 1: Lipids Flashcards
What are the two key dietary risk factors for CVD? and explain them (1 point for one risk, 2 points for other risk)
What can they both lead to? (1 point)
high saturated fats (triglycerides) in diet:
- – liver uses saturated fats to make LDLs which carry cholesterol in the blood from liver to tissues
- if there is too much LDL cholesterol in the blood, tissues cannot take all the cholesterol up into cells, so more remains in the blood
high cholesterol in diet:
1. - if there is more cholesterol than the body needs, more is carried by LDLs in the bloodstream
- Both can lead to high blood cholesterol
What are the consequences of obesity?
7 points
- Strain on the heart - INCREASES BLOOD PRESSURE
- INCREASED LDL BLOOD CHOLESTEROL LEVELS
- Both high blood pressure and LDL blood cholesterol increases the risk of {atheroma/plaque formation/atherosclerosis} as excess cholesterol accumulates in damaged endothelium of the artery wall
- Increased risk of blood clot forming which may block coronary arteries (or arteries to brain)
- Reduced blood supply and oxygen to heart muscle tissue (or brain tissue)
- INCREASED RISK OF HEART ATTACK (or stroke)
- Increases the RISK OF DEVELOPING TYPE II DIABETES
Name the 3 elements that all lipids are made from
Carbon, hydrogen, oxygen
What are the 3 key {roles/functions} of lipids in the human body (3 points)
- energy storage molecules
- phospholipids in cell membranes
- cholesterol in cell membranes
Name the 2 types of molecules which make up a triglyceride
NOTE: Triglycerides are a type of fat (lipid) found in your blood
- glycerol
- fatty acids
NOTE: Glycerol and fatty acids are joined together by ester bonds
What is an essential fatty acid? (2 points)
- one which the body cannot make
2. must be obtained from the diet
Describe the structure of a fatty acid
3 points
- has a carboxyl group (-COOH) at one end
- has a long hydrocarbon chain
- (hydrocarbon chain) can be saturated or unsaturated
Give the 3 structures and 2 properties of saturated fatty acids
Structures:
- no carbon double bonds
- no kinks in the fatty acid chain (so chains pack more closely together)
- higher H:C ratio (maximum number of hydrogens)
Properties:
- Solid at room temperature (due to higher melting point)
- not soluble in water
Give the 3 structures and 2 properties of unsaturated fatty acids
Structures:
- has carbon double bonds
- has kinks in the fatty acid chain (each C=C double bond creates one kink, chains pack less closely together)
- lower H:C ratio
Properties:
- Liquid at room temperature (due to lower melting point)
- not soluble in water
Key Summary: What is the similarity between saturated and unsaturated fatty acids? (1 point)
- Both have a COOH group and a long hydrocarbon chain
Key Summary: What are the differences between saturated and unsaturated fatty acids (3 points)
- Saturated fatty acids have straight hydrocarbon chains and unsaturated fatty acids have KINKS in their chains
- Saturated fatty acids have no CARBON TO CARBON double bonds in their hydrocarbon chains, but unsaturated fatty acids do
- Saturated fatty acids have a higher hydrogen to carbon ratio than unsaturated fatty acids
Key Summary: Explain how a triglyceride is synthesised (5 steps)
- From GLYCEROL AND 3 FATTY ACIDS
- Glycerol bonds to each fatty acid in a CONDENSATION REACTION (specifically called esterification) CATALYSED BY A SPECIFIC ENZYME
- ESTER BONDS {FORM BETWEEN / join} EACH FATTY ACID AND GLYCEROL
- One WATER MOLECULE IS RELEASED for every ester bond that forms (so 3 water molecules in total – 3 ester bonds formed)
- Ester bond forms between the COOH group on the end of a fatty acid and OH of glycerol
Key Summary: What are the similarities between the structure of saturated and unsaturated {lipids/fats/triglycerides}
(2 similarities)
Similarities:
- Both contain only hydrogen, carbon and oxygen
- Both made of glycerol and 3 fatty acids joined by ester bonds
Key Summary: What are the differences between the structure of saturated and unsaturated {lipids/fats/triglycerides} (3 differences)
Differences:
- Saturated fats contain fatty acids which have straight hydrocarbon chains and unsaturated fats have fatty acids with kinks in their chains
- Saturated fats contain fatty acids have no CARBON TO CARBON double bonds in their hydrocarbon chains, but unsaturated fats have fatty acids which do
- Saturated fats contain fatty acids which have a higher HYDROGEN TO CARBON RATIO than the fatty acids in unsaturated fats
What is the state of an unsaturated fat at room temperature (1 point)
explain why. (1 point)
- Unsaturated fats are usually LIQUID at room temperature (have a lower melting point than saturated fats)
- The C=C double bonds cause KINKS in the hydrocarbon chain which prevent fatty acids packing tightly together, so intermolecular bonds are weaker and they can be more easily separated
