Lipids Flashcards
Molecules with 2 ends are
Polar
Triglycerides made up of
3 fatty acids and one glycerol
What does a hydrolysis and condensation reaction produce
Condensation = forms bonds, so forms the triglyceride lipid
Hydrolysis = breaksbonds, forms glycerol and 3 fatty acids
Saturated
No double carbon bonds
What bonds do fatty acids form
Ester bonds
Mono-saturated
1 double bond
What group are lipids
COOH group
Role of lipids
Source of energy
Waterproofing (plants and insects)
Insulation
Protection
Hydrophilic head
Attracted to water and not fat
Polyunsaturated
More than 1 double bond
Reaction called that forms bonds
Condensation
Fatty acid molecules vs phosphate molecules
Fatty acid = repel water, hydrophobic
Phosphate molecules = attract water, hydrophilic
Main groups of lipids
Triglycerides
Test for lipids
1) Add 2cm3 to 5cm3 ethanol in test tube
2) Shake to dissolve lipid
3) Add 5cm3 of water and shake
4) Cloudy white = presence of lipid
Lipids contain
Hydrogen
Carbon
Oxygen
What chains do lipids have
Hydrocarbon
Hydrophobic tail
Orients itself away fro water, mixes with fat
Phospholipids structure
2 fatty acids
1 phosphate molecule
1 glycerol
What are the two groups of lipids
Triglycerides
Phospholipids
How are triglycerides formed
Condensation of one molecule of glycerol and 3 molecules of fatty acid
Is the R group saturated or unsaturated
Can be either
What is the difference between phospholipids and triglycerides
One fatty acid of the triglyceride is substituted for a phosphate-containing group
Are triglycerides polar
Non polar
Hydro[hobic
How can fatty acids vary
Length of R group (hydrocarbon chain)
Saturated or unsaturated R group (hydrocarbon chain)
Are unsaturated fatty acids mono or polyunsaturated
Can be either
Cis-fatty acids = H atom on one side of double bond (COOH)
Trans-fatty acids = H atom on both double bond (CHCH)
What process forms triglycerides
Esterification
Triglycerides formation reaction
Glycerol + 3 fatty acids
Releasing 3H2O during condenation reaction
Both between glycerol and fatty acid forms (esterification) triglycerides
How are triglycerides energy storages
Oxidised during respiration causing bonds to break and release atp
Hydrophobic, dont cause osmotic water uptake = plants form oils in seeds and fruits, mammals store as oil droplets in tissues
How are triglycerides insulation molecules
Part of myelin sheath that surrounds nerve fibres
Increases speed of transmission
Compose part of adipose tissue layer below skin (insulator against heat loss)
Buoyancy
Low density of fat tissue increases ability of animals to float more easily
Protection
Adipose tissue contains triglycerides
Protect organs from risk of damage
WHat are phospholipids major role
Component of cell surface membranes
Describe phospholipids structure
Two fatty acids attached to phosphate and glycerol all linked with glycosidic bond
Word used to describe phospholipids
Amphipathic (both hydrophobic and hydrophilic)
What are the roles of phospholipids
Make bilayer of cell membranes
Barrie to water
COmposition helps fluidity of membrane (many tails less fluid)
Control membrane protein orientation (holds proteins together with hydrophobic interactions but still allows movement within the layer)
Water cant enter easily, controls what substances enter and leave
Test name for lipids
Emulsion test
Why do lipids produce a cloudy soluton with ethanol
Non polar so dont dissolve in water but will dissolve in ethanol
Roles of triglycerides
Energy storage:
-long hydrocarbon tails contain lots of energy released when fatty acids are broken down
-insoluble so dont affect water potential inside the cell
-insoluble droplets so water molecules cannot pass through
WHy are triglycerides goos storage compounds
Insoluble
Contain many bonds that release energy when broken
What are unsaturated fatty acids
Long hydrocarbon chains
With a carboxylic acid with a terminal carboxylic group
Contains double bonds between carbons
