Lipid Metabolism

Question 1

3 steps of fatty acid synth

Answer 1

1. cytosolic entry of acetyl CoA from mitochondrial matix’s TCA
2. Generation of Malonyl CoA
   Most impor substrate, rate limiting step
3. FA Chain formation

Question 2

function of citrate shuttle

Answer 2

1. move acetyl CoA out of mitocondrial matrix to cytosol
   does through combining Oxyloacetate and acetyl CoA to make Citrate. ATP Citrate Lyase splits them up again
2. Move and regenerate oxyloacatate back to mitoch. matrix for TCA

Question 3

What are some inhibitors, promotors of ATP Citrate Lyase?

Answer 3

Inhb. = PUFA, Leptin
Stimulate = insulin, glucose

Question 4

Rate limiting step of FA synth?

Answer 4

Acetyl CoA Carboxylase

Uses Biotin, CO2, ATP, Mg++

Question 5

What form is Acetyl CoA Carboxylase active?

Answer 5

dephospho form.
AMP activates AMPkinase that phorphorlates, and inactivates ACC. This is why AMP inhibits it, if no energy is present, body should be breaking not building things

Question 6

Activators and inhibitors for Acetyl CoA Carboxylase?

Answer 6

Stim: citrate, insulin (dephosphorylation)
Inhib: long chain fa (palmitate, feeback inhb), Phosphorylators: epinephrine, glucagon, AMP

Question 7

What do insulin, glucagon and ephinephrine do to ACC?

Answer 7

ACC, Acetyl CoA Carboxylase,
Insulin: dephosphorylates, activates it
Epine, Glucagon: phosphorylate, inactivate it

Question 8

4 areas FA synth can be regulated?

Answer 8

1. ATP Citrate Lyase (frees Acetyl CoA from Oxyloacetate (phase 1)
2. Acetyl CoA Carboxylase, rate lim step (phase 2)
3. FA Synth (phase 3)
4. Desaturase enzymes

Question 9

Inhibitors of ATP Citrate Lyase?

Answer 9

Leptin***, PUFA

Question 10

Things FA Synthase needs for it to work and make Palmitate (16:0)

Answer 10

(ACP) Acyl Carrier Protein, can make 2 FAs at a time
Works 7 times to make the palmitate
RXNS it does:
reduction, condensation, hydration

Question 11

where does FA synth occur?

Answer 11

partially in mitochon. (for citrate and citrate shuttle)

Cytosol

Question 12

What enzyme introduces double bonds to a FA?

Answer 12

Desaturase enzymes

using NADPH and oxygen,

Question 13

FA lengthen ___ carbons at a time. Cleavage happens ___ at a time.

Answer 13

2

Question 14

essential FAs?

Answer 14

linoleic (omega 6, 18:2) and linolenic (omega 2, 18:3)

acids

Question 15

_____ lipases digest TAGs by cleaving the ____ backbone.

Answer 15

Pancreatic

glycerol

Question 16

Where does beta oxidation of FA occur?

Answer 16

Mitochondria of liver, brain, adipose, kidney

Question 17

What’s the Carnitine shuttle

Answer 17

Bc VLCFAs (turned to LCFAs in peroxisome) or LCFAs cannot enter through diffusion to the mitochondria, they must be ACTIVELY transported.

Question 18

4 enzymes in carnitine shuttle

Answer 18

1. Fatty Acyl CoA Synthetase: uses ATP, forms thioester bond with FAs and CoA,
2. CPT1: Carnitine palmitoyltransferase 1: **rate limiting step in FA degradation
3. CACT: antiporter of carnitine btwn matrix and cytosol
4. CPTII gets FA-CoA into mitorchondrial Matrix for Beta oxidation

Question 19

2 parts of FA degridation

Answer 19

1. Carnitine shuttle

2. Beta oxidation, FAs 16-20 Cs

Question 20

4 steps to beta oxidation (enzymes)

Answer 20

1. Acyl CoA Dehyrdrogenase, FADH2, 1.5 ATP
2. Enoyl CoA Dehydratase
3. 3-Hydoxyacyl CoA dehydrogenase, NADH, 2.5 ATP
4. Acetyl CoA Acetyltransferase (beta-keto thiolase):
   Make ACETYL CoA, and 12 ATPs

Question 21

For Odd #ed FA’s

Answer 21

metab. till Propionyl-CoA, just 3 C left_steps_ turned to succinhyl CoA and sent to TCA

Question 22

Where are very long chained fas metabolized?

Answer 22

> 20 C, in peroxisomes. Once it becomes a Fatty Acyl CoA,n<20, then its sent to mitocondria for Beta oxidation

Question 23

Unsaturated FA’s

Answer 23

reductase remove 2x bond

isomerase moves disruptive bond

Question 24

Beta oxidation in peroxisomes _____ ATP

Answer 24

does NOT

Question 25

______ converts the hydrogen peroxide into water and ___, making it less toxic

Answer 25

Catalase

Oxygen

Question 26

Ketone bodies are ____-soluble and ___ compounds

Answer 26

water
acidic
1. acetoacettae ---> yeilds 23 ATP
2. beta-hydorxybutyrate ---> 26 ATP
3. Acetone (makes it acidic)

Question 27

Where are ketone bodies only produced?

Answer 27

liver

Mitochondrial matrix of hepatocytes

Question 28

What type of sport calls for ketone bodies

Answer 28

marathon running

Question 29

what utalizes ketone bodies?

Answer 29

Brain-if starving
muscle-fasting, marathon running
kideny

Question 30

____ cannot utalize ketone bodies for energy.

Answer 30

RBCs

Question 31

___ and ___ can be cataboolized only to acetyl CoA adn acetoacetate, making them ketogenic.
Both ___ and glycosidic?

Answer 31

Leucine
lysine

PITTT
Phenylalanine
isoleucine
threonine
tryptophan
tyrosine

Question 32

NADH, NAD+ ratios can be affected by

Answer 32

your feeding state
High NADH:NAD+ ratio inhibits TCA, diverts acetyl coA to ketone synth
NAD+ = starvation

Question 33

How can one test for ketone bodies

Answer 33

acetone, glycine in urine and blood

Question 34

order of steps for shortening fatty acyl CoA 2 carbons at a time

Answer 34

oxidation, hydration, oxidation, thiolytic cleavage

Question 35

Even # C FA enter TCA as Acetyl CoA, but odd # FA enter it as ___

Answer 35

succinyl CoA