lecture #4 lipids

Question 1

what is the unifying feature for lipids

Answer 1

they have little to no affinity for water (hydrophobic)

Question 2

what are some example of lipids

Answer 2

• Fats
• Phospholipids
• steroids
• waxes

Question 3

what is the cell membrane made of?

Answer 3

phospholipids and cholesteral (lipids)

Question 4

what is the fat molecule made of

Answer 4

3 fatty acids + 1 molecule of glycerol (triglycerides)

Question 5

why do fat molecules not mix with water?

Answer 5

they have 3 nonpolar (hydrophobic) hydrocarbon tails

Question 6

why do cells use fat for energy storage

Answer 6

the tails hold more potential energy then other biological molecules

Question 7

what the the carbon bonds say about the type of fat

Answer 7

single C-C = saturated fat “Bad” (saturated in H bonds)
double cis C-C = unsaturated fat
double trans C-C = trans

Question 8

what are phosholipids composed of

Answer 8

2 fatty acid + glycerol portion + group containing phosphate (replaces one of the tails) this part is polar and mixes with water (hydrophylic head, hydrophobic tail)

Question 9

what are steroids composed of

Answer 9

same carbon skeleton made of 4 linked rings, differ in what is attached to the rings

Question 10

what is the use of cholesteral

Answer 10

component of the cell membrane

Question 11

what is estradiol

Answer 11

primary female sex hormone produced in ovaries

Question 12

what is testosterone

Answer 12

most abundant male sex hormone

Question 13

what is vitamin d (it is a lipid)

Answer 13

aids in calcium and phosphate metabolism

Question 14

how are the fatty acids linked to the glycerol (p.78 figure 5.9)

Answer 14

by dehydration reaction

Question 15

what is the shape of saturated fats

Answer 15

straight, packed tightly one on top of each other which is why they are usually solid (no cis double bond)

Question 16

what is the shape of unsaturated fats

Answer 16

bent, do not stack one on top of the other, the cis double bond causes them to bend

Question 17

what does hydrogenated mean

Answer 17

hydrogenated vegetable oils” on food labels means that unsaturated fats have been synthetically converted to saturated fats by adding hydrogen. Peanut butter, margarine, and many other products are hydrogenated to prevent lipids from separating out in liquid (oil) form.

Question 18

what does the process of hydrogenating create?

Answer 18

The process of hydrogenating vegetable oils produces not only saturated fats but also unsaturated fats with trans double bonds. It appears that trans fats can contribute to coronary heart disease

Question 19

why are phospholipids important for cells

Answer 19

constiture cell membrane

Question 20

what happends when phospholipids are placed in water

Answer 20

self assemble into a bi-layer to shield the hydrophobic portion

Question 21

what causes kinks in the shape of the fatty acids

Answer 21

cis double bonds

Question 22

what happens when you put a phospholipid in water

Answer 22

they self assemble into by-layers , shielding their hydrophobic portion from water

Question 23

how are steroids recognized

Answer 23

Steroids are lipids characterized by a carbon skeleton consisting of four fused rings (sterol,made of sterol)

Question 24

what type of lipid is cholesteral

Answer 24

steroid

Question 25

what is the name for the linkage between the fatty acids and the glycerol

Answer 25

ester linkage