Biochem 2-1 Tg Synth/breakdown & Beta-Oxidation

Front 1

TG Synth/Lipolysis Pathway:

Back 1

DHAP ↔ Glycerol-3-P → *TG* → Glycerol → Glycerol-3-P ↔ DHAP

Front 2

FAs are transported to adipose as components of_______.

Back 2

lipoproteins

Front 3

Free FAs are transported from adipose bound to ______.

Back 3

albumin

Front 4

Can TGs cross membranes?

Back 4

no; FA components of TGs cross, then reform into TGs w/ a new glycerol backbone.

Front 5

Glycerol-3-P DH

Back 5

DHAP ↔ Glycerol-3-P; all cells

Front 6

Glycerol kinase

Back 6

Glycerol → Glycerol-3-P; liver only, requires ATP

Front 7

Glycerol-3-P→______→Diacylglycerol→TG

Back 7

phosphatidic acid; 1 FA-CoA added at each step

Front 8

Can glycerol be rephosphorylated to G-3-P?

Back 8

yes, only in hepatic cells

Front 9

What can glycerol carbons from TG be used for?

Back 9

GNG

Front 10

In which direction does Glycerol-3-P DH use NADH?

Back 10

DHAP→Glycerol-3-P

Front 11

Where can Glycerol-3-P DH be found?

Back 11

all cells

Front 12

In mucosal cells, TG resynth starts w/ ______, not glycerol-3-P.

Back 12

2-monoacylglycerol

Front 13

As Pancreatic Lipase breaks down TGs, it stops at ______,

Back 13

monoacylglycerol; one FA removal away from Glycerol.

Front 14

What are the products of Pancreatic Lipase used for?

Back 14

Free FAs and monoacylglycerol cross mucosal cell membranes for chylomicron TG synth.

Front 15

Chylomicrons:

Back 15

lipoprotein TGs

Front 16

Lipoprotein Lipase:

Back 16

converts chylomicron TGs to free FAs and Glycerol.

Front 17

What happens to the products of Lipoprotein Lipase?

Back 17

free FAs enter adipocytes for TG synth w/ a new Gycerol-3-P; the orig. glycerol goes to the liver.

Front 18

Adipose Lipase:

Back 18

hormone sensitive lipase; Lipolyzes Adipose TGs to free FAs and glycerol.

Front 19

What happens to the products of Adipose Lipase?

Back 19

the free FAs leave adipocytes bound to albumin, enter beta-oxid cells for catabolism in the mitochondria; glycerol goes to the liver.

Front 20

All glycerol from all TG lypolysis:

Back 20

goes to the liver

Front 21

Fed state Liver Glycerol-3-P:

Back 21

may be catabolized for energy via glycolysis or or rephosphorylated for TG synth.

Front 22

Fasted state Liver Glycerol-3-P:

Back 22

ALL glycerol-3-P converted to Glucose via GNG

Front 23

Pancreatic Lipase activity is controlled by:

Back 23

amount of TG ingested

Front 24

Lipoprotein Lipase activity is controlled by:

Back 24

Fed state activation by Insulin.

Front 25

Adipose Lipase activity is controlled by:

Back 25

activated via phosphorylation by Glucagon and Epinephrine.

Front 26

Where/when does β-oxidation occur?

Back 26

-all FASTED state cells except brain and RBCs.
- Resting skeletal muscle, fed or fasted.
- prolonged exercise in skeletal muscle

Front 27

Is β-oxidation mitochondrial or cytosolic?

Back 27

mitochondrial

Front 28

What are the products of β-oxidation?

Back 28

acetyl CoA, NADH, FADH2

Front 29

How is β-oxidation regulated?

Back 29

Adipose Lipase TG lypolysis

Front 30

Describe the FA journey through β-oxidation:

Back 30

FAs bound to Albumin enter the cell, get activated in the cytosol to Fatty Acyl CoA, enter the miotchondria bound to carnitine, get oxidized to Acetyl CoA.

Front 31

Most FAs for β-oxidation come from_______ action on adipose TG.

Back 31

adipose lipase

Front 32

How does the source of FAs for β-oxidation differ in fed and fasted state skeletal muscle?

Back 32

-Fed: Lipoprotein Lipase action on chylomicrons or VLDL TGs

-Fasted: Adipose Lipase action on adipose TGs

Front 33

_____ is expended in the activation of FAs for β-oxidation.

Back 33

ATP

Front 34

Where does the carnitine for β-oxidation come from?

Back 34

Diet, or made from lysine + methionine

Front 35

What happens to the saturated long fatty acyl chain (even carbon #) during β-oxidation?

Back 35

β-carbon is oxidized to a carboxyl goup, reducing NAD+ and FAD+; the acetyl group is replaced by a CoA group and the process continues until all carbons are oxidized to Acetyl CoA.

Front 36

How does saturated odd carbon # β-oxidation differ from saturated even carbon #?

Back 36

one less acetyl CoA is produced and a propionyl CoA is produced instead.

Front 37

How does β-oxidation of unsaturated FAs differ from saturated?

Back 37

One less FADH2 is produced for each double bond; double bonds are more oxidized than single bonds. Enzymes move the double bonds to the correct Beta carbon position.

Front 38

Is β-oxidation a significant source of carbons for TCA?

Back 38

No; some propionyl CoA is produced by odd carbon # FAs which can enter TCA at Succinyl CoA step.

Front 39

How does medium chain FA β-oxidation differ from long chain?

Back 39

Process is the same except medium chain FAs go from the gut directly to the liver because they are more water soluble and don't require lipoproteins for transport; they are not stored as adipose TGs.

Front 40

Peroxisomal Oxidation

Back 40

Long branched chain and Very Long chain FAs are oxidized to Fatty Acyl CoA compounds for usual Beta-Ox process; involves peroxisomal enzymes; less common

Front 41

ω (omega) oxidation

Back 41

backup process; begins at other end of fatty acyl chain; produces Dicarboxylic Acids.