1. RESPIRATION

2. What is respiration..?

3. The phenomenon of liberation of energy from organic substances in a multistep enzyme mediated catabolic process is described as respiration.

4. TWO DEFINITIONS OF RESPIRATION
BIOCHEMICAL RESPIRATON
PHYSIOLOGICAL RESPIRATION
The metabolic process by which an organism obtain energy by reacting oxygen with glucose to give water ,carbon dioxide & ATP.
It refers to cellular respiration which takes place in individual cell.
It concern with the bulk flow and transfer of metabolites between the organism and external environment.
Breathing is a part of physiological respiration which include exchange of gases.

5. RESPIRATORY QUOTIENT(RQ)
Ratio of volume of CO2 release to the volume of O2 taken in respiration in the given period of time at standard temp. and pressure.
R.Q.= Volume of CO2 evolved
Volume of O2 absorbed

6. R.Q OF CARBOHYDRATES
The volume of CO2 evolved during the process is equal to the volume of O2 absorbed.
Thus the R.Q. is equal to unity.
R.Q. = vol.of CO2
vol.of O2

7. R.Q OF FATS Fats are hydrolysed to fatty acids and glycerol.
Complete oxidation of glycerol results R.Q. of 0.86.
The fatty acids, being poorer in oxygen, require more oxygen for complete oxidation as compared to CO2.
R.Q. become less than unity.

8. R.Q FOR PROTEINS Proteins are hydrolysed into amino acids.
They require more oxygen and evolve less carbon dioxide during their complete oxidation.
R.Q. become less than unity.

9. R.Q FOR ORGANIC ACIDS Acids are rich in oxygen.
Evolve more CO2 & R.Q. become more.
R.Q. of oxalic acid is 4 as shown in the following reaction .
2(COOH)2 + O CO2 + 2H2O+60.2 K cal
R.Q. = vol. of CO2 = = 4
vol. of O

10. RESPIRATORY SUBSTRATES
Organic nutrients which are synthesized inside the plant by anabolic processes (photosynthesis,fat synthesis and protein synthesis).
Respired completely to CO2 and H2O.
Under natural conditions only carbohydrates are oxidized(floating respiration).
If carbohydrates are used up & shortage become acute then other protoplasmic structures may be catabolized (protoplasmic respiration).

11. TYPES OF SUBSTRATES
1. CARBOHYDRATES:- major respiratory substrates in plants. glucose, fructose, sucrose, starch.
R.Q. for carbohydrates-1

12. (a) Starch :- a polysaccharide which is broken down into glucose-1 phosphate units by the action of enzyme starch phosphorylase.
Glucose-1 phosphate is further converted into glucose-6 phosphate by enzyme phospho-glucomutase.
Glucose-6 is an intermediate of glycolysis & oxidized completely to CO2 & H2O.

13. (b) Sucrose:- It is the principal soluble disaccharide which is converted into the glucose and fructose by the action of enzyme invertase.
(C) Glucose:- A monosaccharide hexose molecule which act as chief respiratory substrate.
(d)Fructose:- It is directly converted into fructose-6-phosphate by enzyme fructokinase and then enters into the glycolysis.

14. 2. FATS:- first convereted into fatty acids and glycerol in presence of enzyme lipase.
Fatty acids being poorer in oxygen require more O2 for complete oxidation.
O2 absorption is more and CO2 liberation is less.
R.Q. is less than unity.
Glycerol + ATP Glycerol-3 phosphate + ADP
Glycerol-3 phosphate+ NAD Dihydroxy acetone phosphate + NADH+ H+
Fatty acids are converted into acetyl coenzyme-A which enters into the krebs cycle.

15. 3. PROTEINS:- R. Q is less than unity
3.PROTEINS:- R.Q is less than unity. Proteins are hydrolysed into amino acids. Require more O2 and CO2 liberaton is less. 4. ORGANIC ACIDS:- like malic acid accumulate in dark in some succulents plants(CAM). Under continuous dark period malic acid is converted into CO2 & H2O. COOH 2 + O2 4CO2+2H2O+60.2Kcal.

16. TYPES OF RESPIRATION
1. AEROBIC RESPIRATION:- oxidative breakdown of respiatory substrates with the help of atmospheric O2. Complete breakdown of substrates into CO2 and water.

17. ANEROBIC RESPIRATION
Oxidation of respiratory substrates in absence of O2. Involves incomplete breakdown of respiratory substrates. Ethanol or lactic acid are produced & CO2 is released at the end. C6H12O6 2C2H5OH+2CO2+56 Kcal

18. MECHANISM OF ANEROBIC RESPIRATION
Involves conversion of glucose into ethanol & CO2 in the alcoholic fermentation and the conversion of glucose to lactic acid in the muscles of animals and certain lactic acid bacteria.
The process does not require oxygen.
First glucose is converted into pyruvic acid and then converted into ethyle alcohol or lactic acid.
Occures in cytosol.

19. EMBDEN – MEYERHOF – PARANAS PATHWAY(GLYCOLYSIS)

20. Anerobic respiration carried out by some bacteria&fungi(e. g
Anerobic respiration carried out by some bacteria&fungi(e.g. yeast) is termed as fermentation.
ALCOHOLIC FERMENTATION:-Occures in some fungi(e.g. yeast) and higher plants under anerobic conditions.
It occures in two steps:-
The pyruvic acid is first of all decarboxylated to acetaldehyde in presence of enzyme- pyruvic acid decarboxylase.

21. LACTIC ACID FERMENTATION
The breakdown of pyruvic acid yield lactic acid as an end product.
Pyruvic acid is reduced to lactic acid by
NADH + H in presence of enzyme lactic acid dehydrogenase.COOH
COOH COOH
C =O+ NADH+H CHOH+ NAD
CH CH3
PYRUVIC ACID
LACTIC ACID

22. COOH
C = O CH3 CHO+ CO2
CH3
Acetaldehyde is reduced to ethyle alcohol by NADH + H, produced in glycolysis.
CH3CHO+ NADH+ H C2H5OH + CO2
ACETALDEHYDE
ETHYLE ALCOHAL

23. PRODUCTION OF ATP IN ANEROBIC RESPIRATION
Glycolysis produces 4 ATP's and 2 NADH, but uses 2 ATP's in the process for a net of 2 ATP and 2 NADH.

24. MECHANISM OF AEROBIC RESPIRATION

25. Stepwise breakdown of respiratory substartes to CO2 and H2O in presence of oxygen is referred to as aerobic respiration.
It involve 4 major stages:-
(A) Glycolytic breakdown of glucose to pyruvic acid.
(B) Oxidative decarboxylation of pyruvic acid to acetyl Co A.
(C) Kreb’s cycle.
(D) Terminal oxidation & phosphorylation.

26. (A) GLYCOLYSIS

27. (B) OXIDATIVE DECARBOXYLATION OF PYRUVIC ACID TO ACETYE CO A

28. 2 NADP are produced.
( 1 per pyruvate)
2 CO2 are released.

29. (C) KREBS CYCLE OR TCA CYCLE
Aerobic oxidation of pyruvic acid through a series of reactions was studied in detail by Hans Krebs(1937).

31. PRODUCTION OF ATP IN KREBS CYCLE
8 NADH are produced.
2 FADH2 are produced.
2 ATP are produced.
8 NADH* 3 = ATP
2 FADH2*2 = +4 ATP
2 ATP = +2 ATP
TOTAL = ATP