Lipids

This deck contains content from 3.1.3 Lipids

Are lipids polymers?

No

What elements are lipids made of?

• Carbon

• Hydrogen

• Oxygen

• Phosphorous(Phospholipids)

What bonds join the components of lipids?

Ester bonds

How is the proportion of O to C & H in lipids compared to that of in carbohydrates?

It is smaller

Are lipids soluble in water?

No

Are lipids soluble in organic solvents?

Yes

Give examples of organic solvents…

• Alcohols

• Acetone

What are the two types of lipids?

1. Triglycerides

2. Phospholipids

What do saturated fatty acids generally make?

Fats

What do unsaturated fatty acids make?

Oils

What are the 4 functions of lipids?

1. Source Of Energy

2. Waterproofing

3. Insulation

4. Protection

What makes lipids a good source of energy?

When they are oxidised, they provide more than twice the energy as the same mass of carbs & release H₂O

What makes lipids good in waterproofing?

They are insoluble in water

What makes lipids good insulators?

They are slow conductors of heat and electricity, making them good in myelin sheath around nerve cells.

What makes lipids good for protection?

They can be stored around the organs.

What are triglycerides made up of?

A glycerol and 3 fatty acids

Where does the ester bond form?

Between the hydroxyl group of the glycerol & the carboxyl group of the fatty acid.

Are triglycerides polar?

No

Are triglycerides hydrophobic or hydrophilic?

Hydrophobic

What does the condensation of a triglyceride look like?

What makes up a fatty acid?

• A methyl group at one end

• Hydrocarbon chain(unsaturated or saturated)

• A carboxyl group at the other end

What may the hydrocarbon chain in a fatty acid be?

Saturated/unsaturated

What does saturated mean?

There are no carbon-carbon double bonds in the hydrocarbon chain

What does unsaturated mean?

There is at least one carbon-carbon double bond in the hydrocarbon chain.

What are the two types of unsaturated?

• Monounsaturated - one double bond

• Polyunsaturated - more than one

What are the 4 relationships between structure and function in triglycerides?

• High-ratio of energy-storing carbon-hydrogen bonds to carbon atoms, so a great source of energy

• Low mass to energy ratio, so a good storage molecule as a lot of energy can be stored in a small volume

• Large, non-polar molecule that is insoluble in water, so their storage doesn’t affect osmosis in cells or the water potential of them

• High ratio of hydrogen to oxygen atoms, so release water when oxidised and provide an important source of water

What is a phospholipid made up of?

• Two fatty acids

• A glycerol molecule

• A phosphate molecule

Are phospholipids polar?

Yes

What makes phospholipids polar?

• Fatty acids are hydrophobic, so repel water

• Phosphate is hydrophilic, so interacts with water

How does a phospholipid look?

What are the 3 relationships between structure and function in phospholipids?

• Polar molecules, so in an aqueous environment, phospholipid molecules form a bilayer within cell-surface membranes, hydrophobic barrier is formed between the inside and outside of the cell

• Hydrophilic phosphate ‘head’ help to hold at the surface of the cell-surface membrane

• Form glycolipids by combining with carbohydrates within the cell-surface membrane. These are important for cell-recognition

What is the test for lipids called?

The emulsion test

What is the method for the emulsion test?

1. Add ethanol

2. Shake - dissolves and lipid in sample

3. Add water

4. Shake gently

What is the positive result for the emulsion test?

A white emulsion indicates the presence of a lipid