Exam 2: Notes

Question 1

lipids are the building blocks of _____ _____

Answer 1

fatty acids

Question 2

what affects the physical properties of fatty acids

Answer 2

length and saturation

Question 3

16:0 vs. 16:1

Answer 3

16: 0… higher MP, good packing, max van der waals interactions
16: 1… low MP, kink in chain prevents good packing (mostly cis), fewer van der waals interactions

Question 4

lipids are stored as…

Answer 4

triglycerol

Question 5

purposes of fat

Answer 5

energy storage–more energy/atom, not hydrated (hydrophobic, reduces weight)

insulation

membranes

Question 6

hydrogenation of fats makes ____ double bonds

Answer 6

trans

Question 7

plant cell lipid adaptation

Answer 7

use galactose (galactolipids)

sulfogalactolipids b/c phosphate is limited in soil

Question 8

archae

Answer 8

unique membrane structure

long chain monolayer of fatty ethers (ether bond to glycerol)

ether bonds are less reactive so archae can live at extremes

Question 9

monolayer purpose vs. bilayer

Answer 9

heat to monolayer does not cause peeling

heat + bilayer causes separation/peeling away

Question 10

neg polar head group purpose

Answer 10

prevent loss of DNA from inside of cells

protect cell from attack (RNA/DNA has neg charges)

Question 11

sphingolipids

Answer 11

cell-cell recognition

fatty acid attached to sphingosine by an amide bond

versatile head group (usually sugars)

Question 12

things to know about fatty acid metabolism

Answer 12

activated with CoASH

degraded in 4 step process

fatty acid activation followed by beta-oxidation

Question 13

products of lipid metabolism and how many you get

Answer 13

FADH2, NADH, acetyl CoA

acetyl CoA = 1/2 # of carbons (16:0 = 8 CoA)

NADH = 1 less than # of CoA (16:0 = 7 NADH)

FADH2 = 1 less than # of CoA (16:0 = 7 FADH2)

Question 14

oxidation of MFA

Answer 14

activated with CoASH, B-ox normally until db reached

isomerase makes db trans then continue as normal

Question 15

products of MFA oxidation compared to saturated

Answer 15

16:1

8 acetyl CoA

7 NADH

6 FADH2 (double bond already present)

Question 16

PFA oxidation

Answer 16

methylene group btw dbs

activation and b-ox normal until db

isomerase makes 1st db trans

reduce 2nd db with NADPH, H+ –> NADP (hydrogenase)

Question 17

products of PFA oxidation compared to saturated

Answer 17

16:2

8 acetyl CoA

6 NADH (1 NADPH needed to turn 2db –> 1db)

6 FADH2

Question 18

B-ox of odd # of FA ex. 15C

Answer 18

proceeds normally until the end

produces propionyl CoA

too small for enzymes of B-ox pathway

converted to TCA intermediate succinyl CoA

Question 19

enzymes used in B-ox of odd # FA

Answer 19

carboxylase w/ biotin (HCO3- + ATP –> H+, ADP, Pi)

isomerase w/ B12

Question 20

acetyl CoA can also form…

Answer 20

ketone bodies

Question 21

ketone bodies

Answer 21

used to export acetyl units w/e CoA b/c its limited

produced in diabetes and starvation (both activate gluconeogenesis)

Question 22

why do diabetes + starvation activate gluconeogenesis

Answer 22

brains prefer glucose as energy

siphons off oxaloacetate from TCA

keeps acetyl CoA from entering TCA, and diverts to ketone bodies

Question 23

lipid biosynthesis

Answer 23

not reverse of B-ox

uses acetyl CoA, NADPH, ATP

coordinately regulated (not happening at same time)

unique intermediate malonyl CoA

Question 24

purpose of malonyl CoA

Answer 24

elongates lipid 2C at a time

loses CO2 in process

Question 25

fatty acid synthase

Answer 25

complex (7 subunits) used to construct lipids

in humans 1 pp

in bacteria 7 separate pps

charged w/ acetyl CoA + malonyl CoA

Question 26

lipid biosynthesis steps

Answer 26

6 step process

loss of CoASH

Question 27

regulation of FA synthesis

Answer 27

each 2C elongation requires ATP + 2 NADPH

palmitoyl CoA inhibits carboxylase b/c end product

citrate from TCA activates b/c shows you have a lot of acetyl CoA

phosphorylation (post-translational modification)

gene expression (whether or not you make the enzyme)

Question 28

unsat FA synthesis

Answer 28

lipid and NADPH are oxidized

O2 reduced to H2O

uses 4e-; 2 from NADPH, 2 from lipid

mixed function oxidase

Question 29

mixed function oxidase

Answer 29

FAD, cyt cofactors

O2, H+, NADPH –> 2 H2O, NADP

needed for prostaglandin synthesis

Question 30

prostaglandins

Answer 30

hormones that cause fever, pain, and inflammation

Question 31

aspirin + ibuprofen

Answer 31

inhibit prostaglandin synthesis

prevent pain and swelling

suicide inhibitors (irreversible covalent modification to key catalytic aa in active site)

Question 32

COX-cyclooxygenase

Answer 32

2 isozymes COX-1 & COX-2

aspirin inhibits both forms

COX-1 inhibition causes stomach irritation

COX-2 inhibition relieves pain and fever

Question 33

COX-1 & COX-2 are quite similar in structure

Answer 33

COX-2 involved in prostaglandin synthesis

COX-2 specific drug kills people (Vioxx)

Question 34

cholesterol syn has how many steps

Answer 34

4

3 acetyl CoA –> mevalonate

mevalonate –> isoprene

several isoprenes –> squalene

squalene –> cholesterol

Question 35

weird hydrogenase in cholesterol syn (HMG-reductase)

Answer 35

HMG-CoA, 2 NADPH, 2H+ –> CoASH, 2 NADP, mevalonate

Question 36

mevalonate

Answer 36

critical intermediate in cholesterol biosynthesis

Question 37

HMG-CoA reducatase

Answer 37

major regulatory point of cholesterol biosyn (makes mevalonate from HMG-CoA)

Question 38

statins

Answer 38

mevalonate analogs inhibit HMG-CoA reductase (lovastatin, zocor)

isoprene used to make cholesterol instead

Question 39

isoprene

Answer 39

precursor for many compounds

must take supplements to replace compounds since used to make cholesterol now

uses carbocation