Chapter 3 - lipids

Question 1

what are lipids?

Answer 1

• molecules containing carbon, hydrogen, and oxygen
• fats = lipids that are solid at room temp
• oils = lipids that are liquid at room temp

Question 2

what are the properties of lipids?

Answer 2

• non polar molecules
• not soluble in water
• macromolecules (built from repeating monomers, like polysaccharides)

Question 3

what are triglycerides?

Answer 3

• combined one glycerol molecule with three fatty acids
• form ester bonds from esterification (condensation reaction) where 3 water molecules formed
• need 3 water molecules added to be broken down

Question 4

what are saturated fatty acids?

Answer 4

• fatty acid chains with no double bonds

Question 5

what are unsaturated fatty acids?

Answer 5

• fatty acids with double bonds between carbon atoms
• monounsaturated = one double bond
• polyunsaturated = more than one double bond
• double bond causes molecule to kink/bend=cant pack closely together=liquid at room temp

Question 6

what are phospholipids?

Answer 6

• modified triglycerides with a phosphate head and two fatty acid chains
• phosphate=extra electrons=negatively charged=soluble in water
• hydrophobic tails, hydrophilic heads
• form bilayer

Question 7

what are sterols?

Answer 7

• complex alcohol molecules=four carbon ring structure with hydroxyl (OH) group at one end
• hydroxyl group=hydrophilic, rest of molecule=hydrophobic

Question 8

what is cholesterol?

Answer 8

• a sterol
• made in liver and intestines
• positioned within phospholipids=adds stability to cell, regulates fluidity

Question 9

what are the roles of lipids?

Answer 9

• membrane formation
• hormone production
• electrical insulation
• waterproofing
• thermal insulation
• cushioning to protect vital organs
• buoyancy for aquatic animals

Question 10

what is the emulsion test for lipids?

Answer 10

1) mix sample with ethanol
2) mix solution with water and shake
- positive result=white emulsion forms