Lipids

Question 1

What are lipids?

Answer 1

Macromolecule (NOT polymers) which are only soluble in organic solvents such as alcohols

Question 2

What is the structure of lipids?

Answer 2

Glycerol + fatty acids

Question 3

Draw the structure of a glycerol molecule

Answer 3

-correct drawing

Question 4

Draw the structure of a fatty acid-

Answer 4

• correct drawing

Question 5

Features of a saturated fatty acid-

Answer 5

-saturated with hydrogen atoms
-no c=c double bonds

Question 6

Features of unsaturated fatty acids?

Answer 6

-less saturated with hydrogen atoms
-1 or more c=c double bonds which cause kinks in the chain

Question 7

Why are UFA more fluid and have smaller boiling point that SFA

Answer 7

The kinks in the chain push the molecules apart slightly

Question 8

Why are all fatty acids insoluble in water?

Answer 8

They are non-polar molecule and cannot form hydrogen bonds in the water

Question 9

Draw the bonding of a glycerol molecule with one fatty acid

Answer 9

-correct drawing

Question 10

What is a triglyceride?

Answer 10

One glycerol and three fatty acids

Question 11

What type of reaction makes a triglyceride? What reaction to break it apart?

Answer 11

-Condensation
-Hydrolysis

Question 12

Bond formed in a triglyceride?

Answer 12

Ester bond

Question 13

What are the 5 functions of triglycerides?

Answer 13

1) Energy source
2)energy store
3)insulation
4)buoyancy
5)protection

Question 14

How are triglycerides a good energy source?

Answer 14

-broken down in respiration to release atp
-ester bond in a hydrolysed and glycerol and fatty acids are broken down into CO2 and water

Question 15

How are triglyceride a good energy store?

Answer 15

-insoluble= can be stored without affecting water potential
-mammals store under skin
-lipids have more H atoms than carbohydrates so they can release more energy per gram

Question 16

How are triglycerides good insulators?

Answer 16

-lipids in nerve cells act as electrical insulator
-animals store an extra layer of fat in preparation for hibernation

Question 17

How do triglycerides help with buoyancy?

Answer 17

-fat less dense than water, helps aquatic animals to float

Question 18

How are triglycerides good for protection?

Answer 18

-fat around delicate organs absorbs shock
-peptidoglycan wall of some bacteria covered in a lipid-rich outer coat

Question 19

What is a phospholipid?

Answer 19

Similar to a triglyceride except one fatty acids is replaced with a phosphate group

Question 20

Draw a phospholipid-

Answer 20

-correct drawing

Question 21

Which parts of the phospholipids are polar and attracted to water and which parts aren’t?

Answer 21

-The phosphate group has a negative charge making it polar and hydrophilic
-the fatty acids tails are non polar and hydrophobic

Question 22

Which parts of the phospholipids are polar and attracted to water and which parts aren’t?

Answer 22

-The phosphate group has a negative charge making it polar and hydrophilic
-the fatty acids tails are non polar and hydrophobic

Question 23

What is a phospholipid monolayer?

Answer 23

Layer of phospholipids on the surface of water with heads sticking into the water and fatty acids tails sticking up out of the water.

Question 24

What is a phospholipid bilayer?

Answer 24

Two rows of phospholipids with tails point inwards and heads pointing out.
-typically for membranes around cells and organelle

Question 25

What is a phospholipid Micelle?

Answer 25

Balls with tails inside and head on the outside

Question 26

What is a phospholipid Micelle?

Answer 26

Balls with tails inside and head on the outside

Question 27

Phospholipids are found in membranes, name their functions-

Answer 27

-fluidity= individual phospholipids are able to move around in their layer

-stability= they will not move to a position that exposes their tails to water

-selectively permeable= only small non-polar molecules can move through the bilayer (Oxygen and CO2)

Question 28

What is cholesterol?

Answer 28

-A lipid made from 4 carbon based rings instead of glycerol and fatty acids
-it is small and hydrophobic

Question 29

Functions of cholesterol?

Answer 29

-Membrane fluidity= sits between hydrophobic fatty acid chains, keeps it fluid at low temps and prevents it becoming too fluid at high temps
-used to produce steroid based hormones