1. Respiration
Dr. A.K.M. Shafiqul Islam

2. Respiration is an energy-producing process in which organic or reduced inorganic compounds are oxidized by the inorganic compounds
When an oxidation other then oxygen is involved, the process is called anaerobic respiration.
In aerobic respiration, oxygen is involve, e.g, eucaryotes.

3. Overall respiration is divided in two phases
In the most common forms of respiration, an organic compound is oxidized using oxygen
Overall respiration is divided in two phases
Organic compounds are oxidized to CO2 and a pair of hydrogen atoms are transferred to NAD
The hydrogen atoms are passed through a sequence of reactions, during which ATP is generated from ADP. At the end hydrogen atom will combine with oxygen to give water.

4. TCA OR KREB’S CYCLE

5. TCA Cycle
Additional reducing power is generated from pyruvate by converting it to an acetic acid derivative (acetyl CoA)
CH3COCOOH + NAD+ + CoA-SH
CH3CO-S-CoA + CO2 + NADH + H2
Acetyl CoA is a key intermediate in the catabolism of amino acid and fatty acids
Pyruvic dehydrogenase complex

6. Three classes of biomolecules can be oxidized through acetyl CoA.
The first phase of this oxidation is carried out in cyclic reaction sequence called the tricarboxylic acid or TCA cycle (also Krebs cycle or citric acid cycle)
One carbon atom from pyruvate is lost as CO2 in the reaction of acetyl CoA.

7. Two carbon atom from pyruvate are lost as CO2 through out the TCA circle. The overall stoichiometry of the TCA cycle is
C3H4O3 + ADP + Pi + 2H2O + FAD + 4NAD+
3CO2 + ATP + FADH2 + 4(NADH + H+)

8. TCA CYCLE Occurs within mitochondrial matrix
Multi-step metabolic pathway
Remnants of glucose completely oxidized
Products:
2 ATP
6 NADH
2 FADH2
4 CO2

9. The TCA cycle

10. The TCA Cycle: Overview
Input: 2-carbon units
Output: 2 CO2, 1 GTP,
& 8 high-energy
electrons

11. Guanosine-5'-triphosphate (GTP)
GTP is involved in energy transfer within the cell. For instance, a GTP molecule is generated by one of the enzymes in the citric acid cycle. This is tantamount to the generation of one molecule of ATP, since GTP is readily converted to ATP

12. Respiratory chain reaction
NADH + H+ +1/2 O2 + 3 ADP + 3Pi
NAD+ + 4 H2O + 3 ATP
and
FADH2 + ½ O2 + 2 ADP + 2Pi
FAD + 3 H2O + 2 ATP
Overall reaction
Glucose + 6 O2
6 CO2 + 6 H2O DGo’= -696 kcal/mol

13. Overall reaction of glucose oxidation
EMP reaction + two times TCA cycle + ten times [oxidation of all NADH + H+ generated in EMP (two) and TCA reactions (four)] and two FADH2 oxidation gives
C6H12O ADP + 38 Pi
6 CO ATP + 44 H2O