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Glucose Utilization. Metabolic Mainstreet. Glucose. Glycolysis. Pyruvate. Bridging Rx. AcetylCoA. NAD + /FAD. NADH/FADH 2. C 6. C 4. OP. Krebs Cycle. ADP O 2. C 5. C 4. ATP. PATHWAYS: 4 W’s. W hat = Net Reaction. W hy = Purpose(s) of Pathway.

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Glucose Utilization


Metabolic Mainstreet

Glucose

Glycolysis

Pyruvate

Bridging Rx.

AcetylCoA

NAD+/FAD

NADH/FADH2

C6

C4

OP

Krebs

Cycle

ADP

O2

C5

C4

ATP


Pathways 4 w s
PATHWAYS: 4 W’s

What = Net Reaction

Why = Purpose(s) of Pathway

Where = Organism/Tissue/Organelle

When = Regulation of Pathway


Glycolysis net reaction what
GLYCOLYSIS: Net Reaction (What)

GLUCOSE + 2ADP + 2NAD+

10 Enzymes

2PYRUVATE + 2ATP + 2NADH

Glucose gets oxidized - NAD+ gets reduced

Two ADP molecules get phosphorylated

Glycolysis is a a) catabolic b) anabolic pathway?

Do bacteria have a glycolysispathway?

a) yes b) no c) only anaerobic bacteria


GLYCOLYSIS: Purpose (Why)

1. Generate ATP

a. immediate (2 “anaerobic” ATP)

b. future - more ATP from pyruvate & NADH

2. Provide intermediates/pyruvate for synthesis reactions

Where?

When?

All Organisms:

bacteria, plants, animals

Low Energy Charge

phosphofructokinase (-) ATP

hexokinase (-) G-6-P

pyruvate kinase (-) ATP

All Cell Types:

liver, muscle, brain, adipose, etc.

Cytoplasm


OH

O

HO

OH

OH

OH

OH

O

OH

HO

OH

OH

CH2 – OH

|

CH – OH

|

CH2 – OH

glycerol

CHO

|

CH – OH

|

CH2 – OH

glyceraldehyde

COO-

|

CH – OH

|

CH2 – OH

glycerate

a - Glucose

b - Fructose


COO-

|

CH – OH

|

CH2 – O - PO32-

Name this molecule.

a) Glycerol phosphate

b) Glyceraldehyde 3 phosphate

c) 3 – phosphoglycerate

d) 1 - phosphoglycerate


COO-

|

C=O

|

CH3

pyruvate

COO-

|

C-OH

||

CH2

enol pyruvate

CH2 - OH

|

C=O

|

CH2 - OH

Dihydroxy acetone


GLYCOLYSIS

Glucose

Glucose-6-Phosphate

Fructose-6-Phosphate

Fructose 1,6 Bisphosphate

DHAP + Glyceraldehyde-3-P

Pyruvate

PEP

2-Phosphoglycerate

3-Phosphoglycerate

1,3-BPG

Glyceraldehyde-3-P


Glucose in

2 ATP → 2 ADP

C6→ 2C3

2 NAD+ reduced → 2 NADH

4 ADP → 4 ATP

2 pyruvate out




Glycolysis net reaction what1

fuel in

GLYCOLYSIS: Net Reaction (What)

SH2NADH ATP

S NAD+ADP

work

output

GLUCOSE + 2ADP + 2NAD+

10 Enzymes

2PYRUVATE + 2ATP + 2NADH

Glucose gets oxidized - NAD+ gets reduced

Two ADP molecules get phosphorylated

What is the limiting reagent for glycolysis?

a) Glucose b) ADP c) NAD+


Aerobic

~ 36 ATP

Metabolic Mainstreet

Glucose

NAD+

Glycolysis

NADH

Pyruvate

Bridging Rx.

Lactate

AcetylCoA

NADH/FADH2

How do you supply

NAD+ to glycolysis

When a lack of O2

Prevents OP!

C6

C4

OP

Krebs

Cycle

ADP

O2

C5

C4

ATP


Glycolysis anaerobic

Lactate

GLYCOLYSIS: Anaerobic

GLUCOSE + 2ADP + 2NAD+

10 Enzymes

2PYRUVATE + 2ATP + 2NADH

COO-

|

NAD++ H - C - OH

|

CH3

COO-

|

C = O + NADH

|

CH3

Muscle

Liver

Lactate Dehydrogenase (LDH)


GLYCOLYSIS : Side Reactions

Glucose

Glucose-6-Phosphate  Glycogen

 R-5-P/Glucose

Fructose-6-Phosphate

2,3 BPG

Fructose 1,6 Bisphosphate

DHAP + Glyceraldehyde-3-P

Pyruvate

PEP

2-Phosphoglycerate

 3-Phosphoglycerate

1,3-BPG

Glycerol

Glyceraldehyde-3-P


GLYCOLYSIS: Regulation

Glucose

(-) G-6-P 2nd

Glucose-6-Phosphate  Glycogen

Fructose-6-Phosphate

(-) ATP 1st

Fructose 1,6 Bisphosphate

DHAP + Glyceraldehyde-3-P

Pyruvate

(-) ATP

PEP

2-Phosphoglycerate

3-Phosphoglycerate

1,3-BPG

Glyceraldehyde-3-P


E

P

Metabolic Regulation

1. How Much Enzyme - Regulation of gene expression

2. Activity of Available Enzyme

Allosteric Enzymes

Covalent Modifications

Proenzymes

S

Conditions in the cell (Goldilocks and the three Bears)

a) Too much P – slow down pathway

b) Too little P – speed up pathway

c) [P] is just right – maintain steady state


Allosteric Enzymes

R state (relaxed) – active: S → P

T state (tense) – inactive (or less active): very little P formed

T↔ R + S ↔ R + P

A negative regulator (-) will bind selectively to the less active form of an enzyme,

shifting the conformational equilibrium toward this form and decreasing activity.

[T] increases and [R] decreases

T-↔(- regulator) + T↔ R + S ↔ R + P

A positive regulator (+) will bind selectively to the more active form of an enzyme,

shifting the conformational equilibrium toward this form and increasing activity.

[T] decreasesand [R] increases

T↔ R + S ↔ R + P

+ (+ regulator)↔ R++ S


GLYCOLYSIS: Regulation

Glucose

(-) G-6-P 2nd

Glucose-6-Phosphate  Glycogen

Fructose-6-Phosphate

(-) ATP 1st

Fructose 1,6 Bisphosphate

DHAP + Glyceraldehyde-3-P

Pyruvate

(-) ATP

PEP

2-Phosphoglycerate

3-Phosphoglycerate

1,3-BPG

Glyceraldehyde-3-P


1

(-) G-6-P

3

(-) ATP


Phosphofructokinase has distinct active and allosteric sites

ATP is a negative allosteric regulator

Muscle (M4) - ↑ATP decreases PFK activity


Liver Glycolysis Regulation

↑Liver Glycolysis

↓Liver Glycolysis

3 days

Long Term Fast

Liver Gluconeogenesis

provides glucose to

blood/brain.

Liver Glycogenolysis

provides glucose to

blood/brain.


Liver (L4) - ↑ATP decreases PFK activity

↑ F-2,6-bP blocks ATP allosteric effect and S cooperativity

↑[citrate] also enhances ATP (-) effect (signals sufficient building blocks)

The liver runs glycolysis in the Fed state and blocks glycolysis in the Fasting State.

This initially seems counterintuitive …….


Gluconeogenesis what
GLUCONEOGENESIS ― What?

to blood

2Pyruvate + 4ATP + 2NADH

2GTP

Glucose + 4ADP + 2NAD+

2GDP

Where? Liver

Why? To maintain blood [glucose] after glycogen is used up

When? Fasting state – (particularly late fast)

↑ [acetylCoA] and glucagon


Gluconeogenesis

3 days

Long Term Fast

Liver Gluconeogenesis

provides glucose to

blood/brain.


Metabolic Mainstreet

Glucose

Glycolysis

Pyruvate

Bridging Rx.

AcetylCoA

NAD+/FAD

NADH/FADH2

C6

oxaloacetate

OP

Krebs

Cycle

ADP

O2

C5

C4

ATP


Gluconeogenesis - Bypass Enzymes

Glucose

oxaloacetate

Glucose-6-Phosphate

Fructose-6-Phosphate

Fructose 1,6 Bisphosphate

DHAP + Glyceraldehyde-3-P

Pyruvate

PEP

2-Phosphoglycerate

3-Phosphoglycerate

1,3-BPG

Pyruvate carboxylase

PEP carboxykinase

Glucose 6-

phosphatase

Fructose 1,6-bis phosphatase

Glyceraldehyde-3-P


10. Pyruvatecarboxylase & PEP carboxykinase

(+) acetylCoA & (-) ADP

pyruvate + CO2 + ATP + H2O  oxaloacetate + ADP,Pi + 2H+

oxaloacetate + GTP  PEP + GDP + CO2

  • Fructose 1,6-bisphosphatase

  • (-) fructose 2,6-bisphosphate (low fasting – high Fed)

  • (-) AMP

fructose 1,6 bisphosphate + H2O  fructose 6-phosphate + Pi

1. Glucose 6-phosphatase

glucose 6-phosphate + H2O  glucose + Pi

Gluconeogenesis - Bypass Enzymes


Where does pyruvate come from

Pyruvate

Oxaloacetate

DHAP

Glucose

Lactate

Amino

Acids

Glycerol

Where does Pyruvate come from?


Metabolic Mainstreet

& fasting state

Protein

Glucose

Glycolysis

Pyruvate

Fat

Bridging Rx.

amino acids

AcetylCoA

Fatty acids

NAD+/FAD

Transamination &

oxidative deamination

NADH/FADH2

C6

oxaloacetate

OP

Krebs

Cycle

ADP

O2

C5

C4

ATP


Glycolysis

Fed State

insulin

Liver Regulation

Gluconeogenesis

Fasting State

glucagon

(-) ATP

(-) citrate

(+) F-2,6 BP

(+) AMP

phosphofructokinase

Fructose-6-Phos

Fructose 1,6 Bisphos

(-) AMP

(-) F-2,6 BP

(+) citrate

Fructose 1,6-bisphosphatase

(-) ADP

PEP carboxykinase

PEP

Pyruvate

(-) ATP

(-) Alanine

(+) F-1,6 BP

Pyruvate kinase

oxaloacetate

(-) ADP

(+) AcetylCoA

Pyruvate carboxylase


Cori cycle recycling lactate
Cori Cycle : Recycling Lactate

Liver

Muscle

Glycogen

Glycogen

Glucose

Lactate

Glucose

Lactate



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