1.3 Lipids

Question 1

What are the two types of lipids?

Answer 1

Triglycerides;
Phospholipids

Question 2

Where are triglycerides commonly found?

Answer 2

In food;

Question 3

What do phospholipids help to form?

Answer 3

Cell membrane;

Question 4

Why are lipids good thermal and electrical insulators (neurons)?

Answer 4

Conduct heat slowly;

Question 5

Where are lipids stored?

Answer 5

Delicate organs;

Question 6

Why is it important lipids are stored around delicate organs?

Answer 6

Protects them;

Question 7

Name a delicate organ.

Answer 7

Kidneys;

Question 8

What are triglycerides made from?

Answer 8

One molecule of glycerol and three molecules of fatty acids;

Question 9

What are the fatty acids and glycerol in triglycerides joined by?

Answer 9

Ester bonds;

Question 10

Why are triglycerides not polymers?

Answer 10

Made of different monomers;

Question 11

What catalyses the formation of ester bonds?

Answer 11

Condensation reactions;

Question 12

What do saturated fatty acids not have between carbon atoms within the hydrocarbon chain?

Answer 12

Double-bonds;

Question 13

What do unsaturated fatty acids have between carbon atoms within the hydrocarbon chain?

Answer 13

Double-bonds;

Question 14

Where are double bonds between carbon atoms in a lipid?

Answer 14

Within the hydrocarbon chain;

Question 15

Why are triglycerides good stores of energy?

Answer 15

Low mass to energy ratio;

Question 16

Why does storing triglycerides not affect the water potential of the cell?

Answer 16

Insoluble in water;

Question 17

What is the hydrogen to oxygen ratio compared to carbohydrates (2:1) ?

Answer 17

High;

Question 18

What does having a high hydrogen to oxygen ratio compared to carbohydrates (2:1) mean for triglycerides function?

Answer 18

Good source of water;

Question 19

When are triglycerides a good source of water?

Answer 19

When broken down;

Question 20

To complete the emulsion test, what is placed into a test tube with a small of sample?

Answer 20

2cm cubed Ethanol;

Question 21

In the emulsion test, why is the ethanol/sample mixture shaken?

Answer 21

Fat dissolves in the alcohol;

Question 22

How is water added in the emulsion test?

Answer 22

Drop by drop, then shaken again;

Question 23

What is the layer present if that is present when the emulsion test has been completed?

Answer 23

A cloudy white emulsion of fat drops;

Question 24

What is the primary component of all membranes?

Answer 24

Phospholipids

Question 25

What is a fatty acid group replaced with in phospholipids compared to a triglyceride?

Answer 25

A phosphate group;

Question 26

What is the charge of the phosphate group?

Answer 26

Negative (polar);

Question 27

What charge do the fatty acid tails have?

Answer 27

No charge (non-polar);

Question 28

Is the phospho-glycerol head hydrophobic or hydrophilic?

Answer 28

Hydrophilic

Question 29

What does hydrophilic mean?

Answer 29

Attracts water-soluble;

Question 30

Are the fatty acid tails in a phospholipid hydrophobic or hydrophilic?

Answer 30

Hydrophobic

Question 31

What is meant by hydrophobic?

Answer 31

Repels water - not soluble;

Question 32

What do phospholipids form in water?

Answer 32

Bilayer;

Question 33

What is the inside of the cell known as?

Answer 33

Intercellular space;

Question 34

What is the outside of the cell known as?

Answer 34

Extracellular space;

Question 35

Where do the fatty acid tails face in a phospholipid bilayer?

Answer 35

Towards each other/away from the water;

Question 36

Where do the polar phosphate hydrophilic heads face in a phospholipid bilayer?

Answer 36

Water facing;

Question 37

What forms the basis of the cell membrane?

Answer 37

Phospholipid bilayer;