1. Respiration
ATP as currency of energy.
Ultra structure of mitochondrion and its functions.
Mechanism of aerobic and non aerobic respiration.
Significance of respiration.

2. Respiration
 Energy is stored as organic food in plants.
 Energy is released when organic food is oxidised
during respiration.
 Potential energy in food is converted into kinetic
energy.
 Energy releasing and energy supplying process.
 The energy released is of two types:
Heat energy
Chemical energy

3. Definition
It is an intracellular oxidation process in
which complex organic substances are
broken down into simpler substances
with stepwise release of energy.

4. Raw materials
 Glucose
 Oxygen
Product
 38 ATPs or 686 Kcal or 2870 KJ
Byproduct
 Carbon dioxide

5. Reaction
C6 H12O6 + 6CO2
Enzymes
6H2 O + 6CO2 + 686 Kcal or 38 ATP

6. Overview of Respiration
Respiration involves:
1. Gaseous exchange
 External respiration
 Internal respiration
1. Catabolic process
 Exergonic process
 Formation of water

7. Types of Respiration
1. Aerobic Respiration
The oxidation of the glucose with the help of atmospheric
oxygen is called aerobic respiration.
C6 H12 O6 + 6O2 6CO2 + 6H2 O + 38 ATP
2. Anaerobic Respiration
The partial oxidation of organic food in the absence of
atmospheric oxygen is called anaerobic respiration.
C6 H12 O6 2C2 H5 OH + 6CO2 + 2 ATP

8. Aerobic respiration Anaerobic respiration
Requires molecular oxygen. Does not molecular oxygen.
Respiratory substrate is fully oxidized. Respiratory substrate is incompletely or
partially oxidized.
End products: CO2 and H2O End products: Ethyl alcohol and CO2
Exchange of gases between environment and Exchange of gases is not involved.
organism
Metabolic water is formed Metabolic water is not formed.
Occurs partly in cytoplasm and partly in Occurs entirely in cytoplasm.
mitochondria.
38 ATP molecules formed from a glucose 2 ATP molecules from a glucose molecule
molecule.
Involve electron transport chain. ETC not required.
Process runs continuously throughout life in Occurs continuously only in some
plants and animals. microorganisms. In others it takes place
temporary for short period during oxygen
deficiency.

9. Respiratory substrate
The organic substances which are oxidized in
cellular respiration for releasing energy are
called respiratory substrate.
a. Carbohydrates:
glucose, fructose, starch, glycogen, sucrose.
b. Fats: when carbohydrates are exhausted, fats
are used as respiratory source.
c. Proteins: used as respiratory substrate under
starvation.

10. ATP
 ATP is energy rich organic compound which stores
biologically usable form of energy.
 Universal carrier of chemical energy in living world.
 Energy currency of cells.
 Energy released when ATP is hydrolyzed to ADP and AMP.
ATP + H2 O ADP + ip + 7.3 Kcal
 Energy is stored when ADP & AMP are phosphorylazed to
ATP.
ADP + ip ATP

11. ATP - Structure
 It is a ribonucleotide consisting of 3 components:
a. Adenine
b. Ribose
c. Three Phosphate groups
 Adenine + Ribose = Adenosine.
 1st Phosphate group is attached to Ribose and
then to each other in a linear fashion.

12. ADENINE
RIBOSE
SUGAR
α β γ
PO4 PO4 PO4
ADENOSINE PHOSPHATE
GROUPS

13. ATP - Functions
 Storage of energy.
 Supply of energy.
 Minimization of energy wastage.
 Phosphate group donor

14. Mitochondria
 Double membrane bounded.
 Center for aerobic respiration.
 Present in all living eukaryotic cells.
 Differ in shape. (filamentous, rod shaped).
 0.5- 1µm in diameter & 2-6µm in length.
 Colorless

15. Mitochondria – Structure
A) Mitochondrial membranes
 Outer membrane
 Inner membrane
 Cristae
 Elementary particles
B) Mitochondrial chambers
 Outer membrane
 Inner membrane

16. Mitochondrial membrane
oOuter membrane- permeable to certain solutes.
Consists of 40% lipids & 60% proteins.
oInner membrane- consists of 80% proteins & 20%
lipids. Selectively permeable.
oCristae- inner membrane infolded into the matrix.
Encloses a narrow space called intracristal space.
Contains enzymes for respiration
oElementary particles- present on inner surface of
inner membrane. Named as FI particles or Oxysomes.
Range between 104-105 in a single mitochondrion.

17. Mitochondrial chamber
 Outer chamber- present between outer & inner
membrane. Filled with watery fluid and few enzymes. It
temporarily stores ATP molecules after synthesis.
 Inner chamber- central cavity of mitochondrion filled
with more dense, semi fluid, granular matrix. Matrix
contains enzymes, DNA, RNA, ribosomes. 2- 6
circular double stranded of molecule DNA.

20. Mitochondria -Functions
 Power house of cell
 Intermediate compounds
 Calcium storage and its release
 Thermogenesis
 Maternal inheritance

21. Aerobic respiration
Aerobic respiration is completed in
Glycolysis
Oxidative carboxylation (Acetylation)
Krebs cycle
Electron transport system

22. Glycolysis
 The sequence of reactions in which glucose (6C) is
broken down into two molecules of pyruvic
acid(3C).
 Also called as EMP pathway named after their
discoverers Embden, Meyerhoff, and Paranas.
 1st step in breakdown of glucose.
 Does not require presence of oxygen & there is no
output of carbon dioxide.
 Occurs in cytoplasm of cell.
 Involves series of 10 reaction, each controlled by a
specific enzyme.

23.  The reactions are studied in three groups:
Activation or phosphorylation of glucose
molecule.
Cleavage or fragmentation
Oxidation.

24. Activation

25. Activation or Phosphorylation of
Glucose
1. Phosphorylation of glucose
◦ Glucose is converted to Glucose 6- phosphate
2. Isomerisation
◦ Glucose 6- phosphate isomerised to Fructose 6-phosphate.
3. Second phosphorylation
◦ Fructose 6-phosphate is phosphorylased to Fructose 1, 6-
diphosphate by enzyme Phosphofructokinase(PFK).

26. Cleavage or Fragmentation
4. Cleavage
◦ Fructose 1, 6 bi phosphate is an unstable compound and
splits to produce 3C compounds 3PGAL and DHAP.
5. Isomerisation
◦ Glycolysis utilizes only PGAL, therefore DHAP is
isomerised to 3PGAL

27. Oxidation
6. Oxidative phosphorylation(Dehydrogenation):
o 3PGAL is oxidized by removal of Hydrogen(H2) and
simultaneous phosphorylation of the product resulting in 1,3
Di PGA
7. ATP synthesis:
o 1,3 Di PGA is converted to 3 PGA by release of one
phosphate group.
8. Isomerization:
o Phosphate group at 3rd carbon is shifted to 2nd i.e. 3 PGA to
2PGA.

28. 9. Dehydration :
o 2 PGA loses a molecule of water and gets converted to
PEPA
10. ATP synthesis (formation of Pyruvic acid)
o PEPA is converted to Pyruvic acid by removal of phosphate
group.

29. Net reaction of Glycolysis
C6H12O6 + 2 ADP +2 NAD+ 2 C3H4O3 + 2 ATP +2NADH +
H+ Pyruvic
acid
Net gain of ATP
6 ATP
From 2 NADH2
+ 4ATP
Directly formed
- 2ATP
Utilized
= Net8 ATP
gain

31. Fate of Pyruvic Acid
Glucose
Glycolysis
Pyruvic acid
O2 is used O2 is not used
Aerobic Anaerobic
respiration respiration

32. Acetylation
 Conversion of Pyruvic acid into Acetyl Co- A
 Reaction starts in cytoplasm and completes in
mitochondria
Co A + CO2 +
Pyruvate(3C) Acetyl Co- A (2C)
NAD + NADH2
Pyruvic
dehydrogenas
e

33. Kreb’s cycle
 Also called TCA or Citric Acid cycle.
 Stepwise, cyclic complete oxidation and
decarboxylation of Pyruvic acid into CO2 AND H2O with
release of energy.
 Named after Hans Krebs who traced the sequence of
reactions.
 Takes place in matrix of mitochondria.
 Des not consume ATP molecules.

34. The reactions are as follows:
1. Condensation:
 Acetyl Co-A (2C) combines with Oxaloacetic acid (4C) in
presence of water to form Citric acid(6C).
2. Isomerisation:
 Citric acid first dehydrates to form Cis Aconitic acid and then
rehydrates to form Isocitric acid(6 C).
3. Dehydrogenation:
 Isocitric acid oxidizes to form Oxalosuccinic acid(6C).
4. Decarboxylation:
 With release of a CO2 Oxalosuccnic acid converts to α-Keto
glutaric acid(5C).

35. 5. Oxidative decarboxylation:
 α- Ketoglutaric acid oxidizes & decarboxylates and the product
combines with Co-A to form Succinyl Co-A (4C).
6. ATP synthesis:
 Succinyl Co-A is hydrolysed to Succinic acid(4C).
7. Dehydrogenation:
 Succinic acid is oxidized to Fumaric acid (4C).
8. Hydration:
 Fumaric acid is converted to Malic acid (4C) by addition of
water.
 Malic acid is then oxidised to form Oxaloacetic acid(4C).

37. Net gain of ATP
8NADH2 - 24 ATP ATP synthesis through
2FADH2 - 4 ATP ETS
Direct synthesis - 2 ATP
Total gain of ATP - 30 ATP

38. Electron Transport System
 Final step of aerobic respiration.
 Most ATP and metabolic water generated in this step.
 Located in inner mitochondrial member(cristae &
oxysomes).
 Individual members are called electron carriers.
 Electrons from NADH and Succinate pass through the
ETS to oxygen, which is reduced to water.

40. NADH
Succinate
Complex I
UQ Complex II
Complex III
Cytochrome c
Complex IV
O2

41. Formation of metabolic water
NADH2 or FADH2 NAD or FAD + 2H+ + 2e-
2H+ + 2e- + ½ O2 H2O

42. Reduced ATP through Direct
Steps Total ATP
coenzymes ETS ATP
1.
2 NADH2 2NADH2 X 3= 6ATP 2 ATP 8 ATP
Glycolysis
2.
2 NADH2 2NADH2 X 3 = 6 ATP - 6 ATP
Acetylation
3. Krebs
6 NADH2 NADH2 X 3 = 18 ATP
cycle
2 ATP 24 ATP
2 FADH2 FADH2 X 2 = 4 ATP
C6 H12 O6 + 6 O2 6 CO2 + 6 H2 O + 38 ATP

43. Significance of Aerobic
Respiration
 1 glucose molecule produces 38 ATP molecules.
 Glucose molecule consists 686 k.cal energy.
 Of these only 277.4 k.cal energy (38 X 7.3 k.cal) is
conserved in ATP.
 Remaining energy is lost as heat energy.
 Efficiency of this respiration is 40%.

44. Anaerobic respiration
 The partial incomplete oxidation of organic food in the
absence of atmospheric oxygen is called Anaerobic
respiration.
 Organisms performing anaerobic respiration are called
anaerobes.
 In micro organisms it is known as fermentation.
 No exchange of gases.
 Only 2 ATP molecules are formed.

45. Mechanism
 It is completed in 3 main steps.
1. Glycolysis
2. Decarboxylation
3. Reduction

46. Glycolysis
 First step is similar to glycolysis of aerobic respiration.
C6H12O6 + 2ADP +2NAD+ 2C3H4O3 +2 ATP
+2NADH+H+

47. Decarboxylation
 Pyruvic acid is decarboxylated to form Acetaldehyde
(2C) and CO2 by enzyme pyruvate decarboxylase.
Pyruvate
Decarboxylas
2CH3CO COOH e 2CH3CHO + 2
CO2
Pyruvic acid Acetaldehyde

48. Reduction
 Acetaldehyde
is reduced to Ethyl Alcohol by
NADH2 formed in Glycolysis with the help of
enzyme Alcohol Dehydrogenase.
Alcohol
Dehydrogena
se
Acetaldehyde Ethyl
Alcohol

49. Significance of Respiration
 Release of energy
 Synthesis of ATP
 Stepwise release of energy
 Growth and development
 Energy for biosynthesis
 Role of intermediates
 Balance of CO2 & O2
 Fermentation

50. Thank
you