3.1.3 Lipids Flashcards
What are they the only molecules not to be made up of
polymers
What are the 3 groups of lipids
Fats
Phospholipids
Steroids
4 properties all lipids share
Made from carbon, oxygen and hydrogen
Have less oxygen than carbohydrates
Insoluble in water (hydrophobic)
Soluble in alcohol and acetone (organic solvents)
5 things lipids do
Cell membranes Protection Insulation Energy Waterproofing
What lipids are in cell membranes
What do they do there
Phospholipids
Provide flexibility and control substance movements
What lipids provide protection and where
Fat around delicate organs
What lipids are used for insulation in the body
Why
Fats
They’re slow heat conductors so a thin layer preserves heat
Insulates neurones (myelin sheath) - adipose tissue
What lipids are used for energy when they’re oxidised, what do they do
Fats
Release x2 energy of carbohydrates whilst releasing water
What do plants and animals rely on to make them waterproof
Waxy cuticles
What lipids do mammals release
Oily secretion
What’s the correct name for fats
Triglycerides
What’s the structure of 1 triglyceride
3 fatty acid chains bonded to a glycerol backbone
What are triglycerides in
Butter, oils, foods
What’s glycerol
An alcohol formed from 3 carbons
What does each carbon atom have attached to it in a triglyceride
A hydroxyl group
What’s glycerol bound to in a triglyceride
3 fatty acids
What are fatty acids formed from
Long hydrocarbon chains (usually 16-18 carbons)
What do fatty acids end in
A carboxyl group (COOH)
What are carboxyl groups
Oxygen double bonded to carbon double bonded to hydroxyl group (-COOH)
How many different fatty acids are there
Over 70
What will each different triglyceride have different and the same
Same glycerol
Different fatty acid attached to glycerol
What type of molecules are triglycerides
Non-polar
What do polar molecules have
2 ends (poles) that behave differently from one another e.g 1 side +, 1 side -
Is water polar or non-polar and how
Polar
Hydrogen is slightly positive and oxygen is negative due to electron distribution
What do hydrogen and oxygen in water bond with
Substances that dissolve in water
What are triglycerides unable to do as they’re non-polar
Form hydrogen bonds with water
What are 3 fatty acids bound to the glycerol by
Ester linkages
What reaction forms triglycerides
What is released
Condensation reaction
Water
What are ester linkages broken down by
Hydrolysis
How many water molecules are released when a triglyceride is formed
Why
3
1 molecule released from each ester linkage
What triglyceride is the worst fat
Saturated
What do Saturated triglyceride chains look like
Straight
What do unSaturated triglyceride chains look like
Have a kink in
Which fats are mostly all saturated
Animal fats
What are saturated triglycerides normally at room temperature
Solids
What is the difference between saturated and unSaturated triglycerides
Saturated - no double bonds so maximum number of hydrogens
UnSaturated - double bonds between some carbons so more hydrogen could bind
What’s a triglyceride with 1 carbon-carbon double bond (C=C)
Monounsaturated fatty acid
What’s a triglyceride with more than 1 carbon-carbon double bond (C=C)
Polyunsaturated fatty acid
Example of unSaturated fats
Most plant/fish fats
What are unSaturated fatty acids at room temperature
Oils
What type of molecules are phospholipids
Individual molecules
Where are phospholipids
In cell membranes
Similarity between triglycerides and phospholipids
Both based on glycerol
Difference between triglycerides and phospholipids
Phospholipids Only have 2 fatty acids instead of 3, 1 replaced by a phosphate group
Which part of a phospholipid is the phosphate group
How does it act around water
Head
Hydrophilic
Which part of a phospholipid are the 2 fatty acids
How does it act around water
Tails
Hydrophobic
What’s the shoulder of a phospholipid
Glycerol
What bond is the phosphate group
Ionic
What bond are the fatty acids
Covalent
How do phospholipids arrange in water
Into a bilayer
Which way do the heads and tails face
Heads - outwards
Tails - inwards
Are phospholipids polar or non-polar
Why
Polar
Have 2 ends (poles) that act differently
Why are phospholipids vital parts of the cell membrane
As their bilayer creates a barrier
What does hydrophilic and hydrophobic involve as well as water
Cytoplasm
What’s the test of lipids
The emulsion test
What’s the emulsion test based on
The fact they’re insoluble in water
What’s the method for the emulsion test
Use a dry test tube (no grease/oil) Add 2ml of the solution to test Add 3ml ethanol Shake sample to dissolve any present lipids Filter mixture if necessary Add 5ml water + shake gently
What’s the result of the emulsion test
Any filtrate not dissolved in water forms an emulsion at top (milky white colour due to fat droplets refracting light)
Exposing test tube at end of emulsion test
Fat + ethanol at top (milky white emulsion)
Water at bottom
