Lipids. Flashcards
Gylcerol formula.
C3H8O3.
DIAGRAM.
Fatty acid tail formula.
At beginning, O=C-OH.
CH2 for each new tail.
CH3 at the end.
DIAGRAM.
Trigylceride properties.
One glycerol molecule.
Three molecules of fatty acids.
Fatty acid component can vary but glycerol always the same.
Formation of a triglyceride.
Fatty acids join to glycerol through a condensation reaction.
3 molecules of water are removed.
Ester bonds are formed between glycerol and fatty acids.
By product= 3H2O.
O-C=O is an ester bond.
3 reactions/3 ester bonds/3 water molecules for each triglyceride.
Lose hydrogen from glycerol and OH from the fatty acid= 3H2O.
Hydroxal from glycerol reacts with carboxyl group from fatty acid.
DIAGRAM.
Hydrolysis definition.
Water is chemically inserted in order to split up the H2O formed in the condensation reactions.
Saturated fatty acids.
- If the hydrocarbon chain has only single C-C bonds.
- All Carbon atoms are linked to the maximum possible numbers of Hydrogen atoms= saturated with hydrogen atoms.
- Chain= A straight zig-zag.
- Molecules can align easily so solid at room temp, more packing, strong attraction between fatty acid tails, regular pattern of CH2, fit readily.
- Found in animal lipids.
- Useful for storage in animnals.
DIAGRAM.
Unsaturated fatty acids.
- Carbon-Carbon bond is not a single bond.
- Mono= 1 double bond between Carbons.
- Poly= more than 1 double bond between Carbons.
DIAGRAMS. - Kink in the chain.
- Molecules cannot align uniformly/less packing/less attraction/irregular CH2 pattern so don’t solidify readily and usually liquid at room temp.
- Plant fats.
- Higher number of carbons= higher melting point.
What are steroid hormones made of?
Fats.
Uses of phospholipids.
- In biological membranes.
- Electrical insulation, myelin sheath surrounding axon on nerve cells.
Uses of triglycerides.
- Energy reserves in plants and animals (more C-H bonds than carbs so store more energy).
- Thermal insulation.
- Protection of delicate internal organs.
- Metabolic water (water released during chemical reactions in the body, lots produced by triglycerides when oxidised).
Uses of waxes.
- Waterproofing (reduce water loss in insect exoskeletons or cuticle of plants).
- Buoyancy (less dense than H2O).
Phospholipid structure.
2 fatty acid tails (hydrophobic), Glycerol, Phosphate group (PO4-).
Glycerol+Phosphate group=Phosphate/polar head.
DIAGRAM.
Properties of phosphate head.
Polar= hydrophilic= interacts with water= soluble in water.
Lots of O atoms= polar.
Fatty acid tails properties.
- Hydrophobic.
- Non-polar.
- Does not interact with water.
- No oxygen atoms= non-polar.
Glycerol properties.
Polar.
Hydrophilic.
Interacts with water/soluble.
Structure of phospholipids in cell membrane.
Phosphate head faces outwards.
Fatty acid tails face in.
Out towards the cytoplasm where the phosphate head interacts with the water as it is polar.
Bi layer going all around the cell.
DIAGRAM.
Hydrophobic explanation.
Non-polar.
Does not interact with water.
E.g. Phospholipid tails.
Ethanol.
Cl2.
- Equal distribution of electrons.
- No difference in charge.
Non-polar molecules will interact with other no-polar molecules.
Hydrophilic explanation.
Polar.
Does interact with water.
E.g. Phosphate head.
Water.
O= delta (partially) negative.
H= delta (partially) positive.
-Unequal distribution of electrons.
- Greater pull= slightly negative= delta-.
Polar molecules interact with other polar molecules.
Test for lipids.
Emulsion test:
1) Mix sample with absolute ethanol, which dissolves any lipids present.
2) Shake with an equal volume of water.
3) Dissolved lipids come out of the solution because they are insoluble in water.
4) Forms an emulsion= cloudy, white sample.
Positive (contains lipids)= white emulsion/precipitate formed.
Negative (does not contain lipids)= no emulsion/precipitate formed.
Cholesterol uses.
In cell membrane:
- Regulates/ controls the fluidity of the cell membrane (holds in place or makes it move).
- Gets transported in the blood via 2 ways (HDL or LDL).
LDL.
Low density lipoproteins.
‘Bad cholesterol’.
Deposits cholesterol in the arteries= narrows arteries= high blood pressure.
Coronary heart disease (builds up in coronary heart disease)(stroke?).
Diet high in saturated fat= high levels of LDL build up.
Fatty material (atheroma) gets deposited in the coronary arteries.
Restricts blood flow and Oxygen delivery to the heart.
Completely blocked vessels= myocardial infarction/angina/heart attack.
HDL.
High-density lipoproteins.
‘Happy cholesterol’.
Removes cholesterol from blood/removes built up LDL/cholesterol from arteries.
Diet high in unsaturated fats= high HDL levels in blood.
Carries harmful fats away from arteries to liver for disposal.
Higher ratio of HDL:LDL in blood= lower risk of cardio-vascular and coronary heart disease.
Atherosclerosis.
Fatty deposits in coronary arteries.
Hypertension.
High blood pressure.
When are lipoproteins made.
After food is absorbed at the small intestine, lipids and proteins combine to make lipoproteins then travel around the body in the blood stream.
Ampiphatic defintion.
A molecule with both hydrophobic and hydrophilic properties.
Development of atherosclerosis.
1) Inner wall of artery has smooth endothelium lining.
2) Atheroma deposited on endothlium, reducing available volume for blood flow.
3) Lumen of the artery becomes almost entirely blocked with atheroma.
