1.2 Lipids

Question 1

What are lipids composed of?

Answer 1

Carbon, hydrogen, some oxygen

Question 1

What kind of molecules are lipids

Answer 1

Non polar

Question 2

What is a triglyceride composed of ?

Answer 2

One molecule of glycerol and three fatty acids.

Question 3

What kind of reaction forms a triglyceride?

Answer 3

Condensation reaction

Question 4

What is a condensation reaction?

Answer 4

When two hydrogen atoms and one oxygen atom is removed to join two things

Question 5

What kind of bond joins the glycerol molecule and fatty acid chain ?

Answer 5

Ester bond

Question 6

What is an ester bond ?

Answer 6

Covalent bond formed via condensation reaction between -OH group of a carboxylic acid and an -OH group of an alcohol

Question 7

How is the triglyceride synthesised ?

Answer 7

• Condensation reaction happens between OH- group of carboxlyic acid and OH- group of fatty acid to remove 2 hydrogen and one oxygen which then forms a covalent ester bond between the two

Question 8

What kind of reactions break down a triglyceride ?

Answer 8

Hydrolysis

Question 9

How does a hydrolysis reaction break down the triglyceride?

Answer 9

By adding three water molecules which were previously taken out to then separate glycerol and three fatty acid chains

Question 10

What are triglycerides in general and where can you find them?

Answer 10

A good source of energy, oils butter

Question 11

What are the purposes of phospholipids in an organism ?

Answer 11

• To provide structural role in cell membranes

Question 12

What differentiates unsaturated and saturated fatty acids?

Answer 12

The presence of double carbon bonds in the fatty acid tails

Question 13

Why are some fatty acids saturated?

Answer 13

Fatty acids with hydrocarbon chains that have no double bonds between carbon atoms are saturated

Question 14

Why are some fatty acids unsaturated ?

Answer 14

Fatty acids with one or more double bonds between two carbon atoms make the fatty acid unsaturated

Question 15

What structural change is caused due to the double bond in unsaturated fatty acids and what does this do ?

Answer 15

• Bends in the fatty acid tail which pushes the molecules further apart from each other than saturated molecules

Question 16

What do the bends then cause ?

Answer 16

Reduces intramolecular forces between the triglycerides so they form a liquid at room temp

Question 17

Why are triglycerides a good energy store?

Answer 17

1 - They provide the most energy per unit of mass of any storage molecule, this is useful as it reduces the mass that must be carried around

Question 18

Why are triglycerides water insoluble, why is this important ?

Answer 18

They are large and non polar therefore insoluble. This is important because they do not affect the osmotic balance of cells in the body

Question 19

What is another purpose of triglycerides?

Answer 19

• They can be used as a fat store for insulation

Question 20

What is the difference between a phospholipid and a triglyceride?

Answer 20

• In the phospholipid one of the fatty acids is replaced via a phosphate molecule which is attached to glycerol

Question 21

• How does the phosphate group bind to the glycerol

Answer 21

Via a condensation reaction between the OH groups of phosphoric acid and glycerol to remove water and join the two via cov bond

Question 22

The phospholipid head is ?

Answer 22

Hydrophillic due to negative charge

Question 23

What does hydrophillic

Answer 23

Molecule attracted to water due to charge

Question 24

The fatty acid tails on a phospholipid are ?

Answer 24

HYDROPHOBIC

Question 25

Why are they hydrophboic

Answer 25

• They do not have any charge therefore repel water

Question 26

How do phospholipid bi layers remain fluid ?

Answer 26

Because they can move past and thru each other.

Question 27

What are the roles of phospholipids in cells?

Answer 27

• ## Controls substances in and out of the cell.

Question 28

How can a gene mutation result in an enzyme not being able to digest a lipids (5)

Answer 28

• Change in the DNA sequence
• Change in the primary structure of a protein due to different R groups
• This then leads to different type of bonding
• This then changes the way the protein is folded into its 3D structure
• This causes a change in the active site therefore lipid does not fit in active sit as a substrate anymore

Question 29

What are two dietary factors which cause CVD

Answer 29

High saturated fats
High alcohol intake