Lipids (Biological Molecules) Flashcards
What are Lipids?
They are a group of biological molecules which are insoluble in water but are soluble in organic solvents.
Why are lipids organic?
This is because they contain a lot of carbon atoms.
What are the 2 types of lipids?
1) Triglyceride
2) Phospholipid
What is the role of triglyceride and where are they found?
Triglyceride are good sources of energy and they commonly found in oily food and in butter.
What is the role of phospholipids and where are they found?
They provide support to cell membranes and act as a barrier to protect the cells.
What are lipids composed off?
They are complex macromolecules which consists of C,H,O.
Structure of Triglyceride
A Triglyceride consists of 2 main components:
1) Glycerol molecule ( Have a Hydroxyl group–> OH. It is also an organic alcohol)
2) 3 Fatty Acids (Have a carboxylic group–> COOH and it is an organic acid, can lower ph)
Structure of Phospholipid
Consists of 3 main components:
1) A glycerol molecule
2) 2 fatty acids
3) A phosphate group.
Are lipids hydrophobic or hydrophilic?
Lipids are hydrophobic, they do not mix in water. They form a separate layer.
What are fatty acids composed of?
Fatty acids are made up of long chains of hydrocarbons, and it is usually represented by ‘R’.
Formation of Triglycerides
It is formed in a condensation reaction.
The hydroxyl group on the glycerol molecule, reacts with the carboxylic group on the fatty acids, forming an ester bond.
This formation of the ester bond produces water.
What is an ester bond?
An ester bond is a bond which is formed between the hydroxyl group of the alcohol (OH-) and the carboxylic group of the fatty acids. The formation of this bond releases a water molecule.
How many ester bonds are formed?
3, since there is 3 fatty acids and 3 water molecules are produced.
Breaking of triglycerides.
It is broken down by the process of hydrolysis.
–> 3 molecules of water are required to break down the triglyceride, so 3 ester bonds are broken.
2 variation of fatty acids chain.
1) length of hydrocarbon chain.
2) Unsaturated or saturated fatty acids
What is saturated fatty acids?
These are fatty acids which have no double bonds between the carbon atoms. (C-C)
What are unsaturated fatty acids?
These are fatty acids which have a double bond between carbon atoms. (C=C).
Unsaturated fatty acids exists as monounsaturated and polyunsaturated.
what is polyunsaturated?
They have more than one double bond between carbon atoms.
what is monounsaturated?
They have just one double bond between carbon atoms.
What is the effect of having a double bond in fatty acids?
The double bond between the carbon atoms causes the fatty acids to bend.
Bending effect of fatty acids
Bending results in molecules pushing further apart and it becomes less compact weakening the intermolecular forces.
–> It is said that the lipid is at liquid at room temp. (Oil)
Effect of saturated fatty acids
There is no bend in the fatty acids, so they remain compact. The molecules are closer together.
–> It is said that the lipid is solid at room temp. (Butter)
Roles of lipids
1) Respiration
2) Energy store
3) Other
Lipids in respiration
By hydrolysis reaction, the triglycerides splits into glycerol and fatty acids.
The breaking down of the C-H bonds releases more energy.
