3.4 Lipids Flashcards
(31 cards)
What are the three main groups of lipids?
Triglycerides, phospholipids and waxes.
What are the four characteristics of lipids?
They contain carbon, hydrogen and oxygen.
The proportion of oxygen to carbon and hydrogen is smaller than in carbohydrates.
They are insoluble in water and organic solvents.
Where is the main role of lipids?
In the plasma membrane
What do phospholipids contribute to?
The flexibility of membranes and the transfer of lipid-soluble substances across them.
What are four roles of lipids?
As an energy source
As waterproofing
As insulation
As protection
How do phospholipids work as an energy source?
When oxidised, lipids provide more than twice the energy as the same mass of carbohydrates.
How do phospholipids work as waterproofing?
Lipids are insoluble in water, making them good at waterproofing.
How do phospholipids work as insulation?
Fats are slow conductors of heat and when stored beneath the body surface, they help to retain body heat.
How do phospholipids work as protection?
Fat is often stored around delicate organs, such as the kidneys.
What state are fats in at room temperature?
Solid
What are triglycerides made up of?
Three fatty acids combined with glycerol.
What are the products of a triglyceride going through hydrolysis?
Three fatty acids and a glycerol.
How does each triglyceride vary?
In the fatty acids
How many fatty acids are there?
Over 70
What does every fatty acid have?
A carboxyl group with a hydrocarbon chain attached.
If the hydrocarbon chain in a fatty acid has no carbon-carbon double bond, how is it described?
Saturated.
Why is a hydrocarbon chain described as saturated?
Because all the carbon atoms are linked to the maximum number of hydrogen atoms
If there is a single double-bond, how is it described?
Mono-unsaturated
If there is more than one double bond, how is it described?
Polyunsaturated
What is the difference between lipids and phospholipids?
One of the fatty acids is replaced with a phosphate molecule.
What is the difference between a fatty acid and a phosphate?
Fatty acids are hydrophobic, phosphates are hydrophilic.
What are the two parts of a phospholipid?
A hydrophilic head
&
A hydrophobic tail
What does a hydrophilic head do?
Interacts with water, but not with fat.
What does the hydrophilic tail do?
Orients itself away from water but mixes readily with fat.
