Lipids

Question 1

What are lipids?

Answer 1

Organic molecules made of carbon, hydrogen and oxygen. They cannot dissolve in water as they are non polar, but can dissolve in organic solvents e.g. propanone + alcohols

Question 2

What are triglycerides?

Answer 2

Lipids made by the combination of one glycerol molecule and 3 fatty acid molecules. Glycerol always same, fatty acids vary.
Joined by condensation reaction where 3 water removed and ester bond formed
Show diagram on notes

Question 3

What are roles of triglycerides?

Answer 3

• Energy reserve as lipids contain more C-H bonds than carbs
• thermal insulation, stored under skin
• protection, stored around delicate organs like kidneys to stop physical damage
• produces metabolic water when oxidised

Question 4

What are phospholipids?

Answer 4

Special type of lipids where one end is soluble in water, other is not. Polar head has lots of oxygen atoms in glyecerol + phosphate groups so is hydrophilic, fatty acid tail no oxygen, so hydrophobic and non polar

Question 5

Phospholipid diagram

Answer 5

Notes

Question 6

What are the functions of phospholipids?

Answer 6

• structural, in biological membranes
• electrical insulation, for the myelin sheath that surrounds the axons of nerve cells

Question 7

What are waxes?

Answer 7

Lipids that melt above 45degrees.
Have waterproofing role in insect exoskeleton and cuticle of plant (reduce water loss)

Question 8

What are saturated lipids?

Answer 8

Lipids with no double carbon-carbon bonds, all carbon atoms linked to maximum amount of hydrogen atoms.
Fatty acid chain is a straight line so can readily align so fats are solid.
Semi solid at body temp and used for stowage in mammals

Question 9

What are unsaturated lipids?

Answer 9

Lipids that have double carbon-carbon bonds present. This gives the chain a kink so it cannot align uniformly to readily solidify. So oils are a liquid at room temp.

Question 10

What are High Density Lipoproteins (HDL)

Answer 10

Healthy lipoproteins formed from consumption of unsaturated fats. They travel to pick up and recycle LDL

Question 11

What are Low Density Lipoproteins (LDL)

Answer 11

Unhealthy lipoproteins formed in liver from consumption of saturated fats.
It forms atheromas in arteries which are fatty deposits/plaque.
This may cause development of atherosclerosis, CHO, fatigue or myocardial infunction