Lipid Metabolism Flashcards Preview

MCM: Biochem, Exam 1 > Lipid Metabolism > Flashcards

Flashcards in Lipid Metabolism Deck (35):
1

3 steps of fatty acid synth

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

2

function of citrate shuttle

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

3

What are some inhibitors, promotors of ATP Citrate Lyase?

Inhb. = PUFA, Leptin
Stimulate = insulin, glucose

4

Rate limiting step of FA synth?

Acetyl CoA Carboxylase
Uses Biotin, CO2, ATP, Mg++

5

What form is Acetyl CoA Carboxylase active?

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

6

Activators and inhibitors for Acetyl CoA Carboxylase?

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

7

What do insulin, glucagon and ephinephrine do to ACC?

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

8

4 areas FA synth can be regulated?

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

9

Inhibitors of ATP Citrate Lyase?

Leptin***, PUFA

10

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

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

11

where does FA synth occur?

partially in mitochon. (for citrate and citrate shuttle)
Cytosol

12

What enzyme introduces double bonds to a FA?

Desaturase enzymes
using NADPH and oxygen,

13

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

2

14

essential FAs?

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

15

_____ lipases digest TAGs by cleaving the ____ backbone.

Pancreatic
glycerol

16

Where does beta oxidation of FA occur?

Mitochondria of liver, brain, adipose, kidney

17

What's the Carnitine shuttle

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

18

4 enzymes in carnitine shuttle

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

19

2 parts of FA degridation

1. Carnitine shuttle
2. Beta oxidation, FAs 16-20 Cs

20

4 steps to beta oxidation (enzymes)

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

21

For Odd #ed FA's

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

22

Where are very long chained fas metabolized?

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

23

Unsaturated FA's

reductase remove 2x bond
isomerase moves disruptive bond

24

Beta oxidation in peroxisomes _____ ATP

does NOT

25

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

Catalase
Oxygen

26

Ketone bodies are ____-soluble and ___ compounds

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

27

Where are ketone bodies only produced?

liver
Mitochondrial matrix of hepatocytes

28

What type of sport calls for ketone bodies

marathon running

29

what utalizes ketone bodies?

Brain-if starving
muscle-fasting, marathon running
kideny

30

____ cannot utalize ketone bodies for energy.

RBCs

31

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

Leucine
lysine

PITTT
Phenylalanine
isoleucine
threonine
tryptophan
tyrosine

32

NADH, NAD+ ratios can be affected by

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

33

How can one test for ketone bodies

acetone, glycine in urine and blood

34

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

oxidation, hydration, oxidation, thiolytic cleavage

35

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

succinyl CoA