glycolysis, biochemistry, ATP, B oxidation, glucose,ATP formation, 1st year bsc opto.

1. Glycolysis
NETHRADHAMA
SCHOOL OF OPTO

2. Definition
 The process in cell metabolism by which
carbohydrates and sugars, especially
glucose, are broken down, producing
ATP and pyruvic acid and two "high
energy" electron carrying molecules
of NADH.
Glucose = (C6H12O6)

3. Two phases of glycolysis

4. Step 1
• The enzyme hexokinase phosphorylates (adds a
phosphate group to) glucose in the cell's cytoplasm.

5. Step 2
• The enzyme phosphoglucoisomerase converts glucose
6-phosphate into its isomer fructose 6-phosphate.

6. Step 3
• The enzyme phosphofructokinase uses another ATP
molecule to transfer a phosphate group to fructose 6-
phosphate to form fructose 1, 6-bisphosphate.

7. Step 4
• The enzyme aldolase splits fructose 1, 6-bisphosphate
into two sugars that are isomers of each other. These
two sugars are dihydroxyacetone phosphate and
glyceraldehyde phosphate.

8. Step 5
• The enzyme triose phosphate isomerase rapidly inter-
converts the molecules dihydroxyacetone phosphate and
glyceraldehyde phosphate.
• Glyceraldehyde phosphate is removed / used in next
step of Glycolysis.

9. • Net result for steps 4 and 5:
Fructose 1, 6-bisphosphate↔ 2 molecules of
Glyceraldehyde phosphate (C3H5O3P1)

10. Step 6
• Enzyme triose phosphate dehydrogenase
• Enzyme transfers a hydrogen (H-) from Glyceraldehyde phosphate to
(NAD+) to form NADH.
Triose phosphate dehydrogenase + 2 H- + 2 NAD+ → 2 NADH + 2 H+
• Next triose phosphate dehydrogenase adds a phosphate (P) from the
cytosol to the oxidized glyceraldehyde phosphate to form
1, 3-bisphosphoglycerate.
TPD+ 2P + 2 glyceraldehyde phosphate → 2 molecules of 1,3-
bisphosphoglycerate

11. Step 7
• The enzyme phosphoglycerokinase transfers a P from
1,3-bisphosphoglycerate to a molecule of ADP to form ATP
• This happen for each molecule of 1,3-biphosphoglycerate
Result in step 6: 2 molecules of 3-phosphoglycerate (C3H5O4P1) + 2 ATP

12. Step 8
• The enzyme phosphoglyceromutase relocates the P from 3-
phosphoglycerate from the 3rd carbon to the 2nd carbon to form
2-phosphoglycerate.
2 molecules of 2-Phosphoglycerate (C3H5O4P1)

13. Step 9
• The enzyme enolase removes a molecule of water from
2-phosphoglycerate to form phosphoenolpyruvic acid
(PEP).

14. Step 10
• The enzyme pyruvate kinase transfers a P from PEP to
ADP to form pyruvic acid and ATP
Result in step 10: 2 molecules of 2 ATP + 2NADH

15. Net energyATP utilizedATP produced
2 ATP2ATP
From glucose to
glucose -6-p.
From fructose -6-p
to fructose 1,6 p.
4 ATP
(Substrate level
phosphorylation)
2ATP from 1,3 DPG.
2ATP from
phosphoenol
pyruvate
In absence of oxygen
(anaerobic
glycolysis)
6 ATP
Or
8 ATP
2ATP
-From glucose to
glucose -6-p.
From fructose -6-p
to fructose 1,6 p.
4 ATP
(substrate level
phosphorylation)
2ATP from 1,3 BPG.
2ATP from
phosphoenol
pyruvate.
In presence of
oxygen (aerobic
glycolysis)
+ 4ATP or 6ATP
(from oxidation of 2
NADH + H in
mitochondria).
Energy Production of Glycolysis

16. Beta oxidation of fatty acids

17. Definition
 Beta-Oxidation may be defined as the oxidation of
fatty acids on the beta-carbon atom.
 This results in the sequential removal of a two
carbon fragment, acetyl CoA.

18.  Three stages
1. Activation of fatty acids occurring in the cytosol
2. Transport of fatty acids into mitochondria
3. Beta-Oxidation proper in the mitochondrial
matrix
 Fatty acids are oxidized by most of the tissues in
the body.
 Brain, erythrocytes and adrenal medulla cannot
utilize fatty acids for energy requirement.

19.  Fatty acids are activated to acyl CoA by thiokinases or acyl
CoA synthetases
 The reaction occurs in two steps and requires ATP,
coenzyme A and Mg2+
 Fatty acid reacts with ATP to form acyladenylate which then
combines with coenzyme A to produce acyl CoA.
 There are three thiokinase enzyme to active long chain fatty
acid (12-20 c) , medium chain fatty acid ( 4-12 c),short chain
fatty acid (<4c).

20. R-CH2-CH2-COO-
Fatty Acid
R-CH2-CH2-C-AMP
Acyladenylate
R-CH2-CH2-C-CoA
Acyl CoA
O
O
AT
P
PPi
Thiokinase
PPi
Pyrophosphatase
CoAS
H
AMP

21.  The inner mitochondrial membrane is impermeable
to fatty acids.
 A specialized carnitine carrier system (carnitine
shuttle) operates to transport activated fatty acids
from cytosol to the mitochondria.
 This occurs in four steps
1. Acyl group of acyl CoA is transferred to carnitine (β-
hydroxy γ-trimethyl aminobutyrate)

22. catalyzed by carnitine acyltransferasIe (CAT)
(present on the outer surface of inner mitochondrial
membrane).
2. The acyl-carnitine is transported across the
membrane to mitochondrial matrix by a specific
carrier protein.
3. Carnitine acyl transferase ll (found on the inner
surface of inner mitochondrial membrane) converts
acyl-carnitine to acyl CoA.
4. The carnitine released returns to cytosol for reuse.

23. Carrier
Protein
Acyl
CoA Carnitine
CoASH
Acyl
Carnitine
Acyl
Carnitine
Carnitine
CoASH
Acyl
CoA
CAT-I CAT-II
Cytosol
Mitochondrial
Matrix
Inner
Mitochondri
al
membrane

24.  Each cycle of β -oxidation, liberating a two
carbon unit-acetyl CoA, occurs in a sequence of
four reactions
1. Oxidation
2. Hydration
3. Oxidation
4. Cleavage

25. 1.Oxidation
 Acyl CoA undergoes dehydrogenation by an FAD-
dependent flavoenzyme, acyl CoA
dehydrogenase.
 A double bond is formed between α and β carbons
(i.e., 2 and 3 carbons)
2.Hydration:
 Enoyl CoA hydratase brings
 about the hydration of the double bond to form β -
hydroxyacyl CoA.

26. 3.Oxidation
 β-Hydroxyacyl CoA dehydrogenase
catalyses the second oxidation and generates
NADH.
 The product formed is β-ketoacyl CoA.
4.Cleavage
 The final reaction in β -oxidation is the liberation of
a 2 carbon fragment, acetyl CoA from acyl CoA.
 This occurs by a thiolytic cleavage catalysed by
β-ketoacyl CoA thiolase (or thiolase).

27.  The new acyl CoA, containing two carbons less than
the original, reenters the β-oxidation cycle.
 The process continues till the fatty acid is completely
oxidized.

28. R – CH2 – CH2 – CH2 – C – O
Fatty acid
O
R – CH2 – CH2 – CH2 – C –
Acyl CoA
O
Thiokinase
ATP
AMP + PPi
Mg+2
SCoA
Cytosol
Mitochondria
CoASH
β-Oxidation of fatty acids

29. R – CH2 – CH2 – CH2 – C – SCoA
Acyl CoA
O
FAD
FADH22ATP ----- ETC
Acyl CoA
Dehydrogenase
R – CH2 – CH2 CH2 – C – SCoA
Trans-enoyl CoA
O
R – CH2 – CH – CH2 – C – SCoA
β - Hydroxyacyl CoA
OOH
Enoyl CoA
Hydratase
H2O

30. R – CH2 – CH – CH2 – C – SCoA
β - Hydroxyacyl CoA
OOH
NAD
NADH + H+3ATP ----- ETC
β-Hydroxy Acyl CoA
Dehydrogenase
R – CH2 – C – CH2 – C – SCoA
β - Ketoacyl CoA
OO
Thiolase
R – CH2 – C – SCoA
Acyl CoA
O
CH3 – C – SCoA
Acetyl CoA
O
TCA
Cycle
Acyl CoA

31. Energetics of β -oxidation
Mechanism ATP yield
I. β- 0xidation 7 cycles
7 FADH2 [Oxidized by electron transport Chain (ETC) each
FADH2 gives 2 ATP ]
7 NADH (Oxidized by ETC, each NADH
Liberate 3A TP)
14
21
II. From 8 Acetyl CoA
Oxidized by citric acid cycle, each acetyl CoA
provides 12 A TP
96
Total energy from one molecule of palmitoyl CoA
Energy utilized for activation
(Formation of palmitoyl Co A)
131
-2
Net yield of oxidation of one molecule of palmitate =129