Lipids Chapter 3.5

Question 1

Lipids

Answer 1

Fats and oils. Fats are solid, oils are liquid

Question 2

Triglycerides

Answer 2

Made combining one glycerol molecule and 3 fatty acids

Question 3

Lipids are non-polar

Answer 3

This is because the electrons between the bonds are more evenly spread than in polar molecules, this also means lipids are insoluble

Question 4

Glycerol

Answer 4

It belongs to the alcohols group

Question 5

Fatty acids

Answer 5

Carboxyl groups with a hydrocarbon chain attached to it

Question 6

Saturated

Answer 6

This is when the fatty acid chains have no double bonds so all the carbons have their maximum number of bonds, is compact so is a solid

Question 7

Monounsaturated

Answer 7

Only one double bond which makes a little kink

Question 8

Polyunsaturated

Answer 8

More than one double bond in the fatty acid chains which creates bends in the molecule. This means it’s not as compact as is probably a liquid

Question 9

Phospholipids

Answer 9

These are modified triglycerides that have a phosphate group and 2 fatty acid chains. Contains phosphate ions that have extra electrons so is soluble in water, the rest of the molecule isn’t.

Question 10

Structure of a phospholipid

Answer 10

It has a charged phosphate head that is hydrophilic so is attracted to water and it has 2 fatty acid tails that are hydrophobic so repel water

Question 11

Surfacants

Answer 11

Phospholipids are weird on water. The phosphate head is submerged in the water while the tails stick out this means they are surface active agents or surfacants. Great for forming cell membranes

Question 12

Sterols

Answer 12

Also called steroid alcohols aren’t fats or oils they have a 4 carbon ring with a hydroxyl group on the end. This also means it has a hydrophilic/hydrophobic structure

Question 13

Cholesterol

Answer 13

This is a type of sterol that is very useful in the body. Important in forming cell membranes as it can go in between the phospholipds to make the structure more solid and also maintain the fluidity

Question 14

Biological uses of lipids

Answer 14

Great for membrane formation
Hormone production
Electrical insulation
Waterproofing

Question 15

Biological uses of triglycerides

Answer 15

Great for insulation
Cushioning of vital organs
Buoyancy in marine animals

Question 16

Emulsion test

Answer 16

Add ethanol to sample and mix
Add water and then shake
Then see if white precipitate forms, if so it’s positive

Question 17

Beta oxidation

Answer 17

This is when triglycerides are used for respiration. Its hydrolysed into fatty acids and glycerol. The glycerol is oxidised by beta-oxidation to get glucose needed for respiration.

Question 18

Why is lipid a better energy store than carbohydrates?

Answer 18

Because they have more hydrogens and fewer oxygens so less water is associated. Also, they can be fully oxidised whereas carbs can only be partially oxidised.

Question 19

Iodine Number

Answer 19

Test for the degree of unsaturation. Iodine is added to lipid and if it’s unsaturated the iodine will break the double bond and attach to the hydrocarbon chain. This means it will go from brown to colourless.

Question 20

Hydrogenation

Answer 20

Adding hydrogen to the unsaturated lipid to make it more solid.