Lipids

Question 1

What are lipids?

Answer 1

Fats and oils

Question 2

What are the two types of lipids?

Answer 2

Triglycerides and phospholipids

Question 3

What are triglycerides made up of?

Answer 3

3 fatty acids molecules and 1 glyceride molecule

Question 4

What are phospholipids made up of?

Answer 4

2 fatty acid molecules, 1 glycerol molecule and 1 phosphate group molecule

Question 5

Properties of lipids

Answer 5

-Contains carbon, hydrogen and oxygen but smaller proportions than carbs
-Insoluble in water
-Soluble in organic solvents e.g. acetone and alcohols

Question 6

Roles of lipids

Answer 6

-Contributes to the flexibility of the membrane
-Source of energy = Twice as much energy
-Insulating = Maintains body temperature
-Protection for organs = Layer of fat
-Waterproofing = Waxy cuticle and sebum

Question 7

What are lipids not polymers?

Answer 7

It’s not a polymer because the each part of the lipid has a different structure. It is not made of monomers or ‘repeating units’

Question 8

Fatty acids relationship with water

Answer 8

Repels water -> Hydrophobic

Question 9

How is a triglyceride formed?

Answer 9

Condensation reactions of 1 glycerol and 3 fatty acids. (RCOOH)

Question 10

What bond is formed between glycerol and fatty acids (Carboxyl + Hydroxyl) ?

Answer 10

3 ester bonds

Question 11

Properties of triglycerides

Answer 11

-Good energy storage molecule -> Long fatty acid hydrocarbon tails contain lots of energy, high ratio of C-H compared to C-C bonds
-Insoluble in water -> Doesn’t affect water potential, fatty acid tails are hydrophobic so shield themselves from water
-Low energy : Mass ratio makes them excellent for storage. Reduces mass animals carry around
-High H:O ratio triglycerides release water when oxidised, important source of water

Question 12

What is a glycerol heads relationship with water?

Answer 12

Attracts water -> Hydrophilic

Question 13

What is the R group?

Answer 13

Hydrocarbon chain in the fatty acid

Question 14

What does saturated mean?

Answer 14

No double bond between carbons in the hydrocarbon chain. All available bonds saturated with hydrogens.

Question 15

State of saturated fatty acids at room temperature

Answer 15

Solid at room temperature

Question 16

Where can you find saturated fatty acids?

Answer 16

Meats and dairy

Question 17

What does unsaturated mean?

Answer 17

Has a double bond between carbon atoms in the hydrocarbon chain. Double bond allows them to bend/kink.

Question 18

State of unsaturated fatty acids at room temperature

Answer 18

Cannot pack closely together because of this bend so stays liquid at room temperature

Question 19

Where are unsaturated fatty acids found?

Answer 19

Healthier food options e.g. avocados and vegetable + olive oil

Question 20

How many double carbon bonds do polyunsaturated fatty acids?

Answer 20

More than one

Question 21

How many double bonds so polysaturated fatty acids have?

Answer 21

None

Question 22

Why can’t water soluble can’t pass through the middle layer?

Answer 22

The hydrophobic tails in the middle

Question 23

How does phospholipids arrangement help them?

Answer 23

Helps them maintain the semi-permeable membrane and not pass outside the cell. Water can’t get inside and rebounds of the heads.

Question 24

Test for lipids

Answer 24

1) Add ethanol to sample and mix 2) Add water and mix 3)A white emulsion should form if lipids are present