Chapter 1- Lipids

Question 1

Lipids

Answer 1

Hydrophobic, non-polar molecules (water-hating) bc of hydrocarbon chains
Store energy, provide insulation, cell membranes, synthesis of hormones

Question 2

Triacylglycerol (triglyceride/fats)

Answer 2

is a lipid molecule found in cells called adipocytes. Contain a glycerol backbone and three fatty acids.
Produced by dehydration reactions.

Question 3

Glycerol

Answer 3

organic alcohol molecule that has 3 carbons and 3 hydroxyl groups

Question 4

Fatty acid

Answer 4

long hydrocarbon tail attached to a carboxylic acid.

Question 5

Fats when dehydrated / fats when hydrolyzed

Answer 5

Dehydration/condensation: hydroxyl group of glycerol molecule react with carboxyl acid of fatty acids to produce ester linkage and loss of water.
Hydrolysis: addition of water to fat’s ester bond will break the fatty acid off the glycerol backbone.

Question 6

Saturated fatty acid

Answer 6

has no double bonds and results in pack tightly (solid at room temperature!)
ex: butter

Question 7

Unsaturated fatty acid

Answer 7

have double bonds bc they do not have full hydrogen saturation

Question 8

Monounsaturated fatty acid

Answer 8

has one double bond

Question 9

Polyunsaturated

Answer 9

two or more double bonds

Question 10

Cis-unsaturated fatty acids

Answer 10

create twists in the fatty acid chain bc the hydrogens with the double bond remain on same side.
These twists make it difficult to pack together tightly = liquid at room temperature
ex: olive oil

Question 11

Trans- unsaturated fatty acids

Answer 11

hydrogens go on the opposite side of the double bond = tightly packing fatty acids .

Question 12

Industrial hydrogenation

Answer 12

give cheaper oils the desirable room-stable properties of cis-trans fatty acids

Question 13

Phospholipids

Answer 13

lipid molecules that have a glycerol backbone, one phosphate group, and two fatty acid tails. Ex. of a amphipathic molecule. Phosphate group is polar (hydrophilic) and fatty acids are nonpolar (hydrophobic).
Bc they are amphipathic, they spontaneously assemble into a bilayer in aqueous environment; Cell membranes form through this way

Question 14

Amphipathic molecules

Answer 14

contain hydrophobic and hydrophilic parts

Question 15

Glycolipid

Answer 15

looks like phospholipid but contains carbohydrate molecule instead of phosphate group.

Question 16

Cholesterol

Answer 16

class of lipids containing four hydrocarbon rings and is amphipathic. This allows it to interact with the cell membrane (phospholipid layer) increasing/decreasing the fluidity.

Liver makes cholesterol.
Cholesterol is starting material for vitamin D and precursor to bile acids.

Question 17

Factors that affect fluidity of cell membrane:

Answer 17

Temperature, cholesterol, and degree of unsaturation in phospholipid fatty acid tail.

1. Temperature decreases, phospholipids are packed tight fluidity decreases / temperature increases, fluidity increases
2. Cholesterol at low temp, increases space between phospholipids increasing fluidity / chol. at high temp, pulls phospholipids together fluidity decreases
3. If fatty acids saturated results in tighter phospholipids , fluidity decreases / If fatty acids unsaturated results in bends leaving space, fluidity increases

Question 18

Bile acids

Answer 18

aid in fat absorption

Question 19

Most common steroid precursor

Answer 19

Cholesterol

Question 20

Steriods

Answer 20

fused structures composed of six-membered rings (cyclohexanes) & a five membered ring (cyclopentane)

Ex: cholesterol, testosterone, estrogen

Question 21

Lipoproteins

Answer 21

contain a coat of phospholipids, cholesterol, and proteins. Also have a lipid core containing cholesterol and triglycerides allowing to travel through aqueous environment

Question 22

Low-density lipoproteins (LDLs)

Answer 22

“bad” cholesterol;
low density of proteins; considered unhealthy bc they deposit cholesterol in peripheral tissues like the heart and major blood vessels.
Lead to atherosclerotic blockages and heart diseases.

Question 23

High density lipoproteins (HDLs)

Answer 23

“good” cholesterol
high density of proteins; good because they take cholesterol away from peripheral tissues and deliver to the liver.
Can be used to make bile acids in the liver

Question 24

Waxes

Answer 24

long fatty acids connected to monohydroxy alcohols by ester linkages.
Hydrophobic coating that prevents water absorption

Question 25

Monohydroxy alchohols

Answer 25

molecules that contain one hydroxyl group.

Question 26

Carotenoids

Answer 26

function as pigments provide color to plants and animals.
long fatty acid carbon chains that have conjugated double bonds and 6-membered rings at each end.