3.5 Lipids Flashcards
What elements are lipid molecules made up of
Carbon, hydrogen and oxygen
Are lipids polar
No
Why are lipids non polar
The electrons in the outer orbitals that form the bonds are more evenly distributed than in polar molecules
Why are lipids not soluble in water
There are no positive or negative areas within the molecules
Lipids are large complex molecules know as what
Macromolecules
What is a triglyceride
The combination of one glycerol molecule with three fatty acids
What type of group do fatty acids consist of
A carboxyl group (-COOH) with a hydrocarbon chain attached
What type of group do both glycerol and fatty acids contain
Hydroxyl (OH) groups
What type of reaction is it when a triglyceride is made
A condensation reaction as water is made
What bonds are made in a triglyceride
Ester bonds
What is it called when Ester bonds are made
Esterification
What is a saturated lipid
Fatty acid chains thy have no double bonds present between the carbon atoms
What is an unsaturated lipid
A fatty acid with double bonds between carbon atoms
What doe it mean if a lipid is monosaturated
It has a single double bond
What does it mean if a lipid is polyunsaturated
When there are two or more double bonds
What does the presence of a double bond do to a molecule
Causes the molecule to kink or bend
What is the result of having more than one double bond in a lipid chain
It will be a liquid at room temperature
What is a phospholipid
A modified triglyceride that contains the element phosphorus along with oxygen, carbon and hydrogen
What is the characteristic of phosphate ions that makes them soluble in water
They have extra electrons so are soluble in water
How is a phospholipid made
When one if the fatty acid chains in a triglyceride molecule is replaced with a phosphate group
What is the basic structure of a phospholipid
A charged hydrophilic head attached to two non polar hydrophobic tails
What does hydrophilic mean
Will interact with and are attracted to water
What does hydrophobic mean
Repelled by water
What are surfactants
Molecules that form a layer on the surface when mixed with water
What is a phospholipid bilayer
A two layered sheet formation of the phospholipids with the hydrophilic heads on the outside and the hydrophobic tails on the inside
What are sterols
Another type of lipid that have little in common with others structurally but like lipids have dual hydrophilic/hydrophobic characteristics
What is an example of a sterol
Cholesterol
Where does the body manufacture cholesterol
Liver and intestines
Give 4 roles of lipids
Membrane formation
Hormone production
Electrical insulation
Waterproofing
How do you test for lipids
Emulsion test
How is the emulsion test carried out
First the sample is mixed with ethanol
The resulting solution is mixed with water and shaken
If a white emulsion forms on top of the solution this indicates the presence of a lipid
