2.1.2 Lipids Flashcards
3 categories of lipids
Phospholipids, triglycerides, sterols
6 functions of lipids
Thermal insulation, electrical insulation, respiration, membranes, protection, Energy storage
Lipid structure
Made up of Carbon, Hydrogen Oxygen
- Phospholipids also contain Phosphor
Do not dissolve in water as non polar
Dissolve in organic solvents
Functions of Triglycerides
- Energy storage (respired to release ATP 2x as much as carbs)
- making membrane lipids
Structure of triglycerides
1 glycerol and 3 fatty acid side chains
What is glycerol
An alcohol
What are fatty acids
A carboxylic acid - carboxylate group with an OH group attached
How do fatty acid chain differ
Can have varying lengths
- Essential/ Non essential
- Saturated/ Unsaturated (C=C bond causes kinks in the chain)
- Number of double bonds
What is similar in all triglycerides
All have COOH at the end and methyl group CH3 at the other end
Why are oils liquid
Triglycerides containing unsaturated fatty acids can pack less tightly making them liquid at room temp
Where are oils found and what is their benefit?
Mainly found in plants and they are more healthy to eat
Why are triglycerides insoluble in water
Methyl group is hydrophobic and charges distributed evenly so hydrogen bonds cannot form
How are triglycerides broken down
Hydrolysis
How are the products of hydrolysing triglycerides broken down
Photosynthesis breaks them down into water and CO2
What is metabolic water
The water produced in respiration of lipids (much more than carbs)
What is excess triglyceride stored as
Adipose tissue
What is an ester bond
- formed when an organic acid joins to an alcohol by a condensation reaction (When fatty acid joins to glycerol)
- OH groups interact
- 3 water molecules removed
How can ester bonds be broken
By adding the enzyme lipase
What is the structure of a phospholipid
A glycerol molecule with 2 fatty acid side chains and a phosphate group (modified triglyceride)
What unusual properties does a phospholipid have
Length allows phosphate head and fatty acid tails to differ in solubility
- Phosphate head is charged and so interacts with water molecules
- hydrophobic tails do not interact with water
What happens if phosphate tails are kinked
Kinks are important to allow ions and molecules through membranes
- In winter lots of kinks are needed so that the membrane remains fluid
Phosphate groups can have what attached?
Different chemical groups
What is the purpose of phospholipids
- To create membrane bilayers
- To change membrane fluidity
- Act as surfactants on lining of alveoli
How do surfactants form
Form a layer on surface of water as tails stick out of water as are hydrophobic but hydrophilic heads interact which are found lining the alveoli
