3.5 Lipids

Question 1

What elements are lipid molecules made up of

Answer 1

Carbon, hydrogen and oxygen

Question 2

Are lipids polar

Answer 2

No

Question 3

Why are lipids non polar

Answer 3

The electrons in the outer orbitals that form the bonds are more evenly distributed than in polar molecules

Question 4

Why are lipids not soluble in water

Answer 4

There are no positive or negative areas within the molecules

Question 5

Lipids are large complex molecules know as what

Answer 5

Macromolecules

Question 6

What is a triglyceride

Answer 6

The combination of one glycerol molecule with three fatty acids

Question 7

What type of group do fatty acids consist of

Answer 7

A carboxyl group (-COOH) with a hydrocarbon chain attached

Question 8

What type of group do both glycerol and fatty acids contain

Answer 8

Hydroxyl (OH) groups

Question 9

What type of reaction is it when a triglyceride is made

Answer 9

A condensation reaction as water is made

Question 10

What bonds are made in a triglyceride

Answer 10

Ester bonds

Question 11

What is it called when Ester bonds are made

Answer 11

Esterification

Question 12

What is a saturated lipid

Answer 12

Fatty acid chains thy have no double bonds present between the carbon atoms

Question 13

What is an unsaturated lipid

Answer 13

A fatty acid with double bonds between carbon atoms

Question 14

What doe it mean if a lipid is monosaturated

Answer 14

It has a single double bond

Question 15

What does it mean if a lipid is polyunsaturated

Answer 15

When there are two or more double bonds

Question 16

What does the presence of a double bond do to a molecule

Answer 16

Causes the molecule to kink or bend

Question 17

What is the result of having more than one double bond in a lipid chain

Answer 17

It will be a liquid at room temperature

Question 18

What is a phospholipid

Answer 18

A modified triglyceride that contains the element phosphorus along with oxygen, carbon and hydrogen

Question 19

What is the characteristic of phosphate ions that makes them soluble in water

Answer 19

They have extra electrons so are soluble in water

Question 20

How is a phospholipid made

Answer 20

When one if the fatty acid chains in a triglyceride molecule is replaced with a phosphate group

Question 21

What is the basic structure of a phospholipid

Answer 21

A charged hydrophilic head attached to two non polar hydrophobic tails

Question 22

What does hydrophilic mean

Answer 22

Will interact with and are attracted to water

Question 23

What does hydrophobic mean

Answer 23

Repelled by water

Question 24

What are surfactants

Answer 24

Molecules that form a layer on the surface when mixed with water

Question 25

What is a phospholipid bilayer

Answer 25

A two layered sheet formation of the phospholipids with the hydrophilic heads on the outside and the hydrophobic tails on the inside

Question 26

What are sterols

Answer 26

Another type of lipid that have little in common with others structurally but like lipids have dual hydrophilic/hydrophobic characteristics

Question 27

What is an example of a sterol

Answer 27

Cholesterol

Question 28

Where does the body manufacture cholesterol

Answer 28

Liver and intestines

Question 29

Give 4 roles of lipids

Answer 29

Membrane formation
Hormone production
Electrical insulation
Waterproofing

Question 30

How do you test for lipids

Answer 30

Emulsion test

Question 31

How is the emulsion test carried out

Answer 31

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