Lipids

2 Types : Tryglycerides and Phospholipids Fats (solids) / Oils (liquids) Fatty acids and glycerol Lipase enzymes Long term energy store Insulation Waxy layer —> reduce water loss Insoluble in water Soluble in other solvents eg alcohol Produce metabolic water when respiration occurs Structural - Cell membrane

Contribute to the flexibility of cell membranes Source of energy Waterproofing Insulation Protection

3 Fatty Acids & 1 Glycerol (condensation reaction) Glycerol + 3 Fatty acids = Triglyceride + 3H2O An ester bond is formed between COOC

COOH - R COOH = Carboxylic acid group R = Hydrocarbon Chain O II OH - C - R = 1 Fatty Acid

H 3 Carbons. I H - C - OH 3 OH. H - C - OH 5 Hydrogens. H - C - OH I H

Contains lots of carbon - hydrogen bonds which makes them an excellent source of energy

Low mass to energy ratio which makes them good for storage as much energy can be stored in a small volume

Large, non-polar molecules which makes them insoluble so there storage does not affect osmosis Won’t cause too much water to move into the cell so the cell won’t burst

High ratio of hydrogen to oxygen atoms Triglycerides release water when oxidised so they provide an important source of water especially for organisms in dry deserts they act as a metabolic water source

Saturated fatty acids have only single bonds between carbons in the hydrocarbon chain

Have at least one double bond between carbons in the hydrocarbon chain therefore not holding the maximum number of hydrogen atoms as possible as the bond forms between the carbons and 1 less hydrogen is there

1 Glycerol 2 Fatty Acids 1 Phosphate Fatty Acids are hydrophobic (repel water) Phosphate molecules are hydrophilic (attract water) Charged (hydrophilic) head Non Polar (hydrophobic) tails ⭕️〰️〰️

2 fatty acids bond to the glycerol via 2 condensation reactions resulting in 2 ester bonds Ester bond is the oxygen between the carbons glycerol + 2 fatty acids + phosphate —> phospholipid + 3H2O

Phospholipid + 3H2O —> Glycerol + 2 fatty acids + phosphate

Hydrophilic ‘head’ of a phospholipid can attract with water as it has a negative charge Due to the phosphate being charged, it repels other fats The fatty acid chain is not charged it is known as the hydrophobic ‘tail’ and jt repels water but will mix with fats

Because oxygen and hydrogen have different electro negativity value Oxygen has 2 lone electron pairs that repel each other and the electrons bonded to the hydrogen atoms This gives water molecule a bent shape Oxygen side has a partial negative charge Hydrogen side has a partial positive charge

Phospholipids in water create a phospholipid bilayer (2 layers) Double layer of phospholipids where the tails face each other inwards because they’re repelled by water Hydrophilic heads move on the outside because they can interact with water Phospholipids are polar because they have 2 charged regions

Lipase enzyme Acid/Alkali Triglyceride + 3H2O —> Glycerol + 3 Fatty acids Phospholipid + 3H2O —> Glycerol + 2 Fatty Acids + Phosphate

Similarities: - Both insoluble in water - Both contain glycerol - Both contain ester binds - Both contain C H O Differences : - Triglycerides have 3 fatty acids -Phospholipids have 2 fatty acids + phosphate group -Triglycerides are hydrophobic/non-polar - Phospholipids have hydrophobic and hydrophilic regions

1) Add a small amount of the sample into a test tube with ethanol 2) Shake the mixture so that the fat dissolves 3) Add this to water in another test tube and mix 4) A white emulsion of fat droplets indicated lipid is present