Lecture 19: Fatty Acid Oxidation

Question 1

lipids

Answer 1

have lots of NRG

Question 2

three sources of triacylglycerols

Answer 2

dietary lipids
stored triacylglycerolds (adipose tissues)
fatty acids (synthed in liver)

Question 3

Beta oxidation

Answer 3

how we break down fatty acids

yield NADH FADH2 and acetyl CoA (convert to ATP)

Question 4

Ketogenesis

Answer 4

takes place in liver mitochondria

acetyl CoA levels are high and OOA levels are low

Question 5

fatty acids transported in…

Answer 5

chylomicrons
albumin
VLDL particles

because fatty acidsare hydrophobic

Question 6

what would happen to the plasma membrane if fatty acids inside the cell were not stored as triacyclglycerol

Answer 6

properties of plasma membrane would change

Question 7

where is fat stored

Answer 7

adipocytes

the number of fat cells you’ll have for your life time are determined during childhood

Question 8

we dont break down fatty acids to make glucose. why?

Answer 8

because if you’re breaking down fats, you need the nrg, its more effective to send it to citrate cycle than to make glucose

Question 9

what purpose does fatty acid metabolsim (synth and degredation) serve?

Answer 9

fatty acid oxidation=providing nrg to cells when glucose levles low

Question 10

net reaction

Answer 10

depends on the molec used

Question 11

what are key enzymes for fatty acid metabolism

Answer 11

fatty acyl-CoA synthetase
acetyl CoA carboxylase
fatty acid synth

Question 12

Fatty acid oxidation

Answer 12

generates acetyl CoA, FADH2, NADH2 (thus ATP)

Question 13

fatty acid synthesis

Answer 13

requires ATP, NADPH, acetyl-CoA

Question 14

Orlistat is a drug that inhibits pancreatic lipase. Why does taking Orlistat before eating help you lose weight?

Answer 14

inhibits process of cleaving

you can’t get fatty acids into the cell

Question 15

What might be some of the side effects of Orlistat

Answer 15

indigestion, oily stool

if you don’t cleave them, they stay in the intestine and have to be excrete

Question 16

Transport and storage of fatty acids and triacylglycerols

Answer 16

not soluble in aqueous solutions!
have to be transported in bile acids
Lipases cleave the fatty acid tails and release them
then fatty acids can be transported, triacylglycerol resynthed:
- put into chylomicrons, they are exported into lymphatic system and circulate

Question 17

apo proteins on cylomicrons

Answer 17

tell when chylomicrons when they get to the right place

Question 18

why do the fatty acids have to be carried by albumin protein, why not just release fatty acids directly into the capillaries?

Answer 18

they’re too hydrophobic/insoluble

why not just send the whole thing through the cappilares?? chylomicrons too big

Question 19

what is the central metabolite in this liver pathway that allows non-fat bagels to make you fat

Answer 19

acetyl CoA

Question 20

why is the citrate cycle inhibited when you eat a dozen bagels in one sitting?

Answer 20

energy charge is really high

Question 21

saturated fatty acids

Answer 21

all single bonds
high melting points
pack together really well

Question 22

unsaturated fatty acids

Answer 22

some double bonds

low melting points

Question 23

so what’s “better”

Answer 23

more double bonds means more bending!
number of double bonds affects melting point
so its often liquid at room temp
has lower melting point

longer also has more surface area for binding, so higher MP

Question 24

Cis and Trans

Answer 24

Cis: hydrogens on same side of double bond’
Trans: hydrogen on opposite side of double bond: makes it basically a flat, straight molec (w/ not kinks)

Question 25

how do we get trans then?

Answer 25

hydrogenastion! (some in dairy too)
makes food longer to store
linked to coronary heart disease

Question 26

fatty acid degradation cost

Answer 26

attach fatty acid to an ATP, release of pyrophosphate, which we break into 2 Pi.

so eqivlanet of using 2 ATP for this process

Question 27

why hydrolysis of ATP->AMP and PPi is 2 ATP

Answer 27

used ATP to make AMP and PPi… which goes to 2 Pi. to resynth it, it takes 2 ATP (slide 17)

Question 28

carnitine

Answer 28

transports fatty acids into mitochondrial matrix

transporter brings it in

Question 29

Betaoxidation makes how many ATP?

Answer 29

106 from a 16 carbon molec
remove carbons 2 at a time
we get FADH2, NADH, acetyl CoA
oxidation of these (by citrate cycle)=ATP

Question 30

How many NADH and FADH2 are derived from the oxidation of 8 acetyl coA

Answer 30

31 NADH
15 FADH2

100 ATP

Question 31

review slides 21 and 22

Answer 31

review slides 21 and 22

Question 32

how many acetyl CoAs will you get??

how many NADH and FADH2?

Answer 32

Always one half the number of carbons in the molecs

number of NADH and FADH2 you get are half-1 the number of carbons

Question 33

where does the H2O come from when NADH and FADH2 are oxidized, i.e., what cellular process is responsible for this water?

Answer 33

aerobic respiration at ETS

Question 34

How does phosphprylation of ADP generate H2O?

Answer 34

ADP + Pi releases water

Question 35

Ketogenesis

Answer 35

when we have more acetyl CoA than we can combine with OAA to make citrate, the extra acetyl coA goes to liver and is converted to ketone bodies

Question 36

ketone bodies

Answer 36

nrg source that can be used by other tissues in citrate cycle

Question 37

How many ATP can be gernated from acetoacetate??

Answer 37

20 ATP
we made 2 acetyl CoAs
slide 25

Question 38

when does ketogenesis happen

Answer 38

when blood sugar low and glycogen stores have been depleted

stim of of ketogenesis!!!
fatty acids released from adipose tisues in response to glucagon signaling
fuel ketogen in liver

accumulation of ketone bodies in blood