Respiration

Respiration:
Cell needs energy in order to perform cellular function like growth, Reproduction etc. The energy is available from Glucose which is oxidized in presence or absence of oxygen. During the process CO2 + Water are liberated as by product. Along with synthesis of ATP.

The catabolic process in which Glucose is oxidized in order to liberated energy is called respiration. Which may or may not need oxygen.

Depending on requirement of oxygen Respiration is of 2 types: aerobic and anaerobic.

1. Aerobic respiration (cell)
2. Anaerobic respiration

1) Aerobic respiration:

The respiration which need oxygen oxidised glucose is called Aerobic respiration. Which is feature of higher Organism.
In this process Glucose is Completely Oxidised and liberates CO2 and water along with energy. One molecule of Glucose after aerobic respiration liberate 686 Kcl. this energy is stored in 38 ATP molecule.

2) Anaerobic respiration:

Respiration which take place in absence of Oxygen is called Anaerobic respiration.
It is a charastices of microorganism & also Occurs in involuntary muscles during heavy exercise.

During anaerobic respiration Glucose molecule is partially oxidised into Ethanol form lactic acid and CO2 along with energy. Therefore anaerobic respiration also called partially oxidation and fermentation.

Depending on nature of end product anaerobic respiration is a 2 types: alcoholic fermentation & lactic acid fermentation.

i) Alcoholic fermentation:

When glucose molecule is mixed with fungi it partially oxidises and produces ethanol + CO2. This kind of fermentation is called Alcoholic fermentation. It is widely use brewing industry manufacture alcohol. In this process Glucose molecule produce 54 kcal.

ii) Lactic acid fermentation:

When bacteria respire anaerob it produces lactic acid + Carbondioxide. This kind of fermentation is called lactic acid fermentation. When O2 is difficent volutary muclues respires anaerob and produces latic which Stop Contration & relaxation of musclus.
This Condition is called muscle cramping.

Mechanism of aerobic respiration:

Aerobic respiration needs O2 and Completely Oxidizes Glucose into CO2 & H2O.

The reactions of aerobic respiration take place in 2 region;
Cytoplasm and mitochondria. The rxn are studied under following phases:

1) Glycolysis:

The splitting of Glucose in cytoplasm in absence of oxygen is called Glycolysis. It is a common phase to both aerobic & anaerobic respiration. In this Case Glucose molecules is splitted into 2 molecules of 3 carbon compound named pyruvic acid.
The mechanism of Glycolysis was explained by Embden, meyer-hoff and parnas. Therefore Glycolysis is also called EMP pathway. Which can be represented as:

Mnemonic for Steps:

• Good ⇒ Glucose
• Girl ⇒ Glucose - 6 - phosphate (6C)
• Friend ⇒ Fructose - 6 - Phosphate (6C)
• Fills ⇒ Fructose - 1, 6 - biphosphate (6C)
• Glass ⇒ Glyceraldehyde - 3 - phosphate (3C)
• Daily ⇒ Dihydroxy acetone - phosphate (3C)
• By ⇒ 1, 3 - biphosphoglyceric acid (3C)
• 3 - Peg ⇒ 3 - phosphoglyceric acid (3C)
• 2 - Peg ⇒ 2 - phosphoglyceric acid
• Ploy ⇒ Phosphoenol pyruvic acid
• PUBG ⇒ Pyruvic acid

Pathway Diagram:

Glucose (6C)
↓ Hexokinase (ATP → ADP)
Glucose-6-phosphate (6C)
↓ phosphogluco isomerase
Fructose-6-phosphate (6C)
↓ Phosphofructo kinase (ATP → ADP)
Fructose-1,6-biphosphate (6C)
↓ Aldolase
Glyceraldehyde-3-phosphate (3C) ↔ (Isomerase) ↔ Dihydroxy acetone phosphate (3C)
↓ (2NAD → 2NADH)
1,3-biphosphoglyceric acid (3C)
↓ (2ADP → 2ATP)
3-phosphoglyceric acid (3C)
↓ phosphoglycero mutase
2-phosphoglyceric acid (3C)
↓ Enolase (-H2O)
Phosphoenol pyruvic acid (3C)
↓ Pyruvate kinase (2ADP → 2ATP)
Pyruvic acid (3C)

Phases of Glycolysis:
Glycolysis has two phases: preparatory & pay off phase. Preparatory phase utilizes 2 ATP & Pay off phase releases 4 ATP & 2 NADH. Thus there is net profit of 2 ATP + 2 NADH.

2) Oxidative Decarboxylation:

Pyruvic acid Decarboxylate in presence of pyruviate decarboxylase & produces 2 carbon compound called acetaldehyde. During the process 2 molecules are released.

Acetaldehyde in presence of acetaldehyde dehydrogenase & co-enzymes A produces acetal co-enzyme A. During the process NADH is synthesis.

2x Pyruvic acid → (decarboxylase / 2 CO2) → 2x Acetaldehyde
2x Acetaldehyde → (2NAD+ → 2NADH / Acetaldehyde dehydrogenase) → 2x Acetyl Co-A

Oxidative decarboxylation is also called link rxn betn Glycolysis & Kreb cycle.

3) Kreb Cycle:

When Oxygen is aviable Kreb cycle Occurs in mitochondria. The reaction for this cycle where identify by Hans Krab. There fore cycle is called Krab cycle.
The first stable Product of the Cycle is 6 Carbon compound name Citric acid which has 3 carboxylic acid groups. Therefore Krab cycle is also called Citric acid cycle or TCA cycle (Tricarboxylic acid cycle).

In this cycle Oxidation & isomeration rxn take place & liberates Energy rich electron which are used in synthesizing ATP, NADH & FADH2.

Mnemonic for Kreb Cycle Intermediates:
"Oh citric acid is of course a silly Stupid funny molecule"

• Oh ⇒ Oxaloacetic acid (4C)
• Citric ⇒ Citric acid (6C)
• Acid ⇒ Aconitic acid (6C) (Cis-aconitic)
• Of course ⇒ Oxalosuccinic (6C)
• Silly ⇒ Succinyl CoA (4C)
• Stupid ⇒ Succinic acid (4C)
• Funny ⇒ Fumaric acid (4C)
• Molecule ⇒ Malic acid (4C)

The Flow Chart for this cycle can be presented as:

• Oxaloacetic acid (4C) + Acetyl Co-A (2C) → Citric acid (6C) [Enzyme: Citrate synthase]
• Citric acid → Aconitic acid (6C) [Enzyme: Aconitase]
• Aconitic acid → Isocitrate acid (6C) [Enzyme: Aconitase]
• Isocitrate → Oxalosuccinic → Alpha-ketoglutarate (5C) [Enzyme: Isocitrate dehydrogenase, Releases 2NADH + CO2]
• Alpha-ketoglutarate → Succinyl Co-A (4C) [Enzyme: Alpha-ketoglutarate dehydrogenase, Releases 2NADH + CO2]
• Succinyl Co-A → Succinic acid (4C) [Enzyme: Succinate thiokinase, Releases 2 GTP/ATP]
• Succinic acid → Fumaric acid (4C) [Enzyme: Succinate dehydrogenase, Releases 2 FADH2]
• Fumaric acid → Malic acid [Enzyme: Fumarase]
• Malic acid → Oxaloacetic acid [Enzyme: Malate dehydrogenase, Releases 2 NADH]

Mnemonic for Enzymes/Steps: "Disco Devil Directly Sipped drinks For Darling"

After Complection of Kreb cycle 6 NADH, 2 FADH2 & 2 GTP molecules are synthesized. GTP molecule Isomerises into ATP molecules.

4) Election Transport chain system (ETC):

Complexes:

• Complex I → NADH dehydrogenase
• Complex II → Succinate dehydrogenase
• Complex III → Cytochrome c reductase
• Complex IV → Cytochrome c oxidase
• Complex V → ATP synthase

Mitochondria have Outer & inner membrance bet ween the membrance is a Space called inter membronal Space. Inner membrance have Several enzymes in a Sequences. These enzymes are represented by roman from Ist to Vth.
Each group of Enzymes Constitute Complex.
Complex I has NADH dehydrogenase, Complex II has succinate dehydrogenase, Complex III has Cytochrome C reductase, Complex IV Cytochrome C Oxidase & Complex V beside of Complex IV each an enzyme Called ATP Synthase.

NADH is Oxidase in presence of NADH dehydrogenase & form NAD+ & H+ & electron. H+ is Pump into internal membranal Space & electron are Picked of by Complex I.
Similarly FADH2 is Oxidized in presence of Succinate dehydrogenase & form FADH+, & electron, H+ & electron. H+ is Pump into intermal membranal Space & electron are Picked of by Complex II.
Due to accumulation of H+ positive charge is developed & matrix has Negative charge.

The electron from Complex I & Complex II are handed Over to Ubiquinone which transfer then to Complex III.
The electron From Complex III transfer to Complex IV & then ATP Synthase where ATP molecules are synthesized by utilizig the energy left by rxn.

At the mean time ATP synthase Permeable to H+ & enter for matrix where H+ rec electrons + Oxygen to form water. This phenomenon is Called terminal oxidation.

It is know that one molecule of NADH gives 3 ATP & Two molecules of FADH2 gives 2 ATP. This phenomenon is called oxidative phosphorylation.

Calculation Table

Difference between

Respiration vs Photosynthesis

Respiration vs Photorespiration

Aerobic vs Anaerobic Respiration