lipids

Question 1

what elements do lipids contain

Answer 1

carbon
hydrogen
oxygen

Question 2

what are lipids

Answer 2

fats and oils

fats are solid at room temperature
oils are liquid at room temperature

Question 3

lipids polarity

Answer 3

• non-polar molecules
• as the electrons that form bonds are more evenly distributed than in polar molecules
• this means there are no positive or negative areas in the molecules
• insoluble

Question 4

what are macromolecules

Answer 4

• lipids
• large complex molecules
• not built from repeating units/monomers

Question 5

what is a triglyceride made from

Answer 5

-1 glycerol (alcohol)
- 3 fatty acids (carboxylic acids)

Question 6

by what process are triglycerides made

Answer 6

esterification (condensation reaction)

• hydroxyl groups interact, forming 3 water molecules and ester bonds between the fatty acids and glycerol.

Question 7

what are saturated fatty acids

Answer 7

fatty acid chains that have no double bonds present between the carbon atoms

they are called saturated because all carbon atoms form the maximum number of bonds with hydrogen atoms

Question 8

what are unsaturated fatty acids

Answer 8

• a fatty acid chain with double bonds between some of the carbon atoms

monounsaturated= only 1 bond
polyunsaturated= 2 or more bonds

Question 9

why are unsaturated fatty acids liquid at room temperature

Answer 9

• double bonds causes the molecule to kink or bend
• therefore they cant pack as closely together

Question 10

what are phospholipids

Answer 10

• modified triglycerides
• contain phosphorus, carbon, hydrogen, oxygen
• one of the fatty acid chains in a triglyceride molecule is replaced with a phosphate group to make a phospholipid

Question 11

phospholipids polarity

Answer 11

• non polar fatty acid tails are hydrophobic
• polar phosphate heads are hydrophilic

Question 12

what are sterols

Answer 12

(steroid alcohols)
- type of lipid found in a cell
- not fats or oils, have little in common with them structurally
- complex alcohol molecules
- 4 carbon ring structure with OH on one end
- OH is polar (hydrophilic)
- rest of the molecule is hydrophobic

Question 13

role of cholesterol

Answer 13

• body makes it in liver and intestines
• formation of cell membranes
• positioned between phospholipids
• adds stability to cell membranes
• regulates fluidity

Question 14

lipids’ roles due to their non-polar nature

Answer 14

• membrane formation and creation of hydrophobic barriers
• hormone production
• electrical insulation for impulse transmission
• waterproofing

Question 15

lipids’ (triglycerides) roles in long-term energy storage

Answer 15

-stored under the skin and around vital organs where they provide:
- thermal insulation to reduce heat loss
- cushioning to protect organs
- buoyancy for aquatic animals

Question 16

identification of lipids

Answer 16

emulsion test
- sample is mixed with ethanol
- solution is mixed with water and shaken
- white emulsion forms as a layer on top of the solution (positive)
- solution remains clear (negative)