Lecture 19: Fatty Acid Oxidation Flashcards
lipids
have lots of NRG
three sources of triacylglycerols
dietary lipids stored triacylglycerolds (adipose tissues) fatty acids (synthed in liver)
Beta oxidation
how we break down fatty acids
yield NADH FADH2 and acetyl CoA (convert to ATP)
Ketogenesis
takes place in liver mitochondria
acetyl CoA levels are high and OOA levels are low
fatty acids transported in…
chylomicrons
albumin
VLDL particles
because fatty acidsare hydrophobic
what would happen to the plasma membrane if fatty acids inside the cell were not stored as triacyclglycerol
properties of plasma membrane would change
where is fat stored
adipocytes
the number of fat cells you’ll have for your life time are determined during childhood
we dont break down fatty acids to make glucose. why?
because if you’re breaking down fats, you need the nrg, its more effective to send it to citrate cycle than to make glucose
what purpose does fatty acid metabolsim (synth and degredation) serve?
fatty acid oxidation=providing nrg to cells when glucose levles low
net reaction
depends on the molec used
what are key enzymes for fatty acid metabolism
fatty acyl-CoA synthetase
acetyl CoA carboxylase
fatty acid synth
Fatty acid oxidation
generates acetyl CoA, FADH2, NADH2 (thus ATP)
fatty acid synthesis
requires ATP, NADPH, acetyl-CoA
Orlistat is a drug that inhibits pancreatic lipase. Why does taking Orlistat before eating help you lose weight?
inhibits process of cleaving
you can’t get fatty acids into the cell
What might be some of the side effects of Orlistat
indigestion, oily stool
if you don’t cleave them, they stay in the intestine and have to be excrete
Transport and storage of fatty acids and triacylglycerols
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
apo proteins on cylomicrons
tell when chylomicrons when they get to the right place
why do the fatty acids have to be carried by albumin protein, why not just release fatty acids directly into the capillaries?
they’re too hydrophobic/insoluble
why not just send the whole thing through the cappilares?? chylomicrons too big
what is the central metabolite in this liver pathway that allows non-fat bagels to make you fat
acetyl CoA
why is the citrate cycle inhibited when you eat a dozen bagels in one sitting?
energy charge is really high
saturated fatty acids
all single bonds
high melting points
pack together really well
unsaturated fatty acids
some double bonds
low melting points
so what’s “better”
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
Cis and Trans
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)
how do we get trans then?
hydrogenastion! (some in dairy too)
makes food longer to store
linked to coronary heart disease
fatty acid degradation cost
attach fatty acid to an ATP, release of pyrophosphate, which we break into 2 Pi.
so eqivlanet of using 2 ATP for this process
why hydrolysis of ATP->AMP and PPi is 2 ATP
used ATP to make AMP and PPi… which goes to 2 Pi. to resynth it, it takes 2 ATP (slide 17)
carnitine
transports fatty acids into mitochondrial matrix
transporter brings it in
Betaoxidation makes how many ATP?
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
How many NADH and FADH2 are derived from the oxidation of 8 acetyl coA
31 NADH
15 FADH2
100 ATP
review slides 21 and 22
review slides 21 and 22
how many acetyl CoAs will you get??
how many NADH and FADH2?
Always one half the number of carbons in the molecs
number of NADH and FADH2 you get are half-1 the number of carbons
where does the H2O come from when NADH and FADH2 are oxidized, i.e., what cellular process is responsible for this water?
aerobic respiration at ETS
How does phosphprylation of ADP generate H2O?
ADP + Pi releases water
Ketogenesis
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
ketone bodies
nrg source that can be used by other tissues in citrate cycle
How many ATP can be gernated from acetoacetate??
20 ATP
we made 2 acetyl CoAs
slide 25
when does ketogenesis happen
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
