Lipids

Question 1

What is a lipid

Answer 1

• lipids are fats and oils
• they contain only carbon, oxygen, hydrogen
• they are non polar and insoluble in water
• ## they are large complex molecules (MACROMOLECULES)

Question 2

What is a triglyceride

Answer 2

• it is made up of a glycerol
  C3 H8 O3
• and 3 fatty acid chains which have a carboxyl group(COOH), 17-23 hydrocarbon chain and a methyl group (C H3)
• the fatty acids are joined to the glycerol by Ester bonds

Question 3

Describe the formation of an Ester bond what type of bond is it

Answer 3

• an enzyme cleaves the hydroxide from the carboxyl group of a fatty acid
• another enzyme cleaves the hydrogen from the hydroxide group of the carbon on glycerol
• a covalent bond forms between the oxygen of the hydroxide residue on the glycerol and the carbon on the carboxyl residue of the fatty acid
• an Ester bond is formed
• OH+H=H2O it is a condensation reaction

Question 4

What is the difference between saturated and unsaturated fatty acids

Answer 4

• saturated triglyceride means that every carbon is saturated with hydrogen (no double bonds between carbon)
• unsaturated means there are double bonds between carbon atoms and these make kinks in the hydrocarbon chain
• saturated triglycerides are solid at room temperature, you can get van der call attraction between 2 molecules
• unsaturated are liquid at room temperature

Question 5

What is a phospholipid

Answer 5

• a phospholipid has a glycerol, 2 fatty acid chains and a phosphate group
• the fatty acids are non-polar (hydrophobic)
• phosphate group are charged (hydrophilic)
• they are surfactants in water the phosphate head is in the water whereas the fatty acids are out of the water
• phospholipids create a bilayer separating water from the inside of the cell

Question 6

What is a sterol

Answer 6

• this is an steroid alcohol
• not fats or oils
• they are complex alcohol molecules based on a 4 carbon ring structure
• they have a hydroxyl group at one end and the rest of the molecule is hydrophobic

Question 7

Structure and function cholesterol

Answer 7

• cholesterol is a sterol
• it is made in the liver and intestines
• it plays an important role in the formation of cell membranes, it is positioned between the phospholipids
• it adds stability and fluidity to the membrane keeping it fluid at low temperature and stopping it from becoming too fluid at high temperature
• cholesterol also used to make vitamin D and bile

Question 8

What are the roles of lipids

Answer 8

• membrane formation and creation of hydrophobic barriers
• hormone production
• electrical insulation necessary for impulse transmission
• water proofing eg, birds feathers, plant leaf

Triglycerides in particular

• thermal insulation to reduce heat loss
• cushioning to protect vital organs such as heart and kidneys
• buoyancy for aquatic animals like whales