Lipids

Question 1

What is a triglyceride made from?

Answer 1

One glycerol molecule
Three fatty acids

Question 2

What reaction forms triglycerides?

Answer 2

Condensation reaction (happens 3 times)

Question 3

What bond is formed during a condensation reaction?

Answer 3

Ester bond

Question 4

Why are triglycerides insoluble in water?

Answer 4

Hydrophobic tail (due to the variable ‘R’ group)

Question 5

What is the difference between saturated and unsaturated fatty acids?

Answer 5

Saturated = no double bonds
Unsaturated = at least 1 double bond (results in a kink)

Question 6

Describe features of triglycerides

Answer 6

Energy store
Long hydrocarbon tails (lots of chemical energy released when broken down)
Insoluble (doesn’t affect water potential and cause water to enter cell via osmosis)
Clump together as insoluble droplets (tails face inwards)

Question 7

What is a phospholipid made from?

Answer 7

One glycerol molecule
Two fatty acids
One phosphate molecule

Question 8

Which part of the phospholipid is hydrophobic and which part is hydrophilic?

Answer 8

Phosphate group (head) = hydrophilic
Fatty acid (tail) = hydrophobic

Question 9

Describe the features of a phospholipid

Answer 9

Make up the bilayer of cell membranes
Forms a double layer with their heads facing outwards
Centre of bilayer is hydrophobic (water soluble substances can’t easily pass through)

Question 10

How would you test for lipids?

Answer 10

Emulsion test
- add ethanol to substance
- shake
- add water
- any lipid will show up as a milky emulsion