STATE LEVEL TRAINING FOR DISCTRICT RESOURCE GROUP

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XI Std. Bio-Botany & Botany – Vol. II

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Venue: Sri SaiRam College of Engineering, Chennai

Date: 30.11.18 & 01.12.18

STATE COUNCIL OF EDUCATIONAL RESEARCH AND TRAINING, CHENNAI – 06

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Chapter 14

RESPIRATION�

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Chapter outline

• Gaseous exchange
• Structure of ATP
• Redox reactions
• Types of Respiration
• Stages of Respiration
• Respiratory Quotient
• Anaerobic Respiration
• Factors affecting Respiration
• Pentose phosphate pathway

Plant and animal interdependence

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• To differentiate plant and animal respiration

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• Respiration is a biological process need to sustain life

Gaseous exchange in plants

During day – both absorption of O₂, CO₂ and

removal of O₂, CO₂ are taken place.

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During night CO₂ is removed and O₂ is absorbed.

Gaseous Exchange

According to Blackman, respiration is divided into

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• Floating respiration- carbohydrate, fat & organic acid
• Protoplasmic respiration - protein

Overall equation of Respiration

C₆H₁₂O₆ + 6O₂ 6CO₂+6H₂O+ Energy

(686 Kcal or 2868 KJ)

Compensation point

• The point at which CO₂ released exactly compensated by CO₂ fixed

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• C₃ plants -40 to 60 ppm
• C₄ plants -1 to 5 ppm

Structure of ATP

• Karl Lohman(1929)
• 7.3 Kcal or 30.6KJ.
• Universal energy currency of the cell.
• Energy transformation concept by Lipman(1941).
• Other higher energy
• Compounds-GTP & UTP.

Redox reactions

NAD⁺ + 2e^- +2H⁺ NADH+ H⁺

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FAD + 2e^- +2H⁺ FADH₂

Types of Respiration

Overall stages of Respiration

Glycolysis

• Three scientists
• Gustav Embdon (German)
• Otto Mayerhoff (German)
• J Parnas (Polish)
• Divided into two phases

1. preparatory phase or endergonic phase

2. pay off phase or exergonic phase

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• substrate phosphorylation or direct phosphorylation or trans phosphorylation
• Enolation

1. Glycolysis-preparatory phase

Glycolysis –pay off phase

Energy Budget

4ATP + 2NADH+H⁺ - 2ATP= 2ATP + 2NADH+H⁺

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Overall Net Reaction of Glycolysis

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C₆H₁₂ O₆ + 2ADP + 2Pi+ 2NAD⁺

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2xCH₃ COCOOH + 2ATP + 2NADH+2H⁺

2. Pyruvate oxidation

• Also called transition reaction or Link reaction

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2xCH₃COCOOH + 2NAD⁺ +2Co A

Pyruvate dehydrogenase complex/Mg⁺⁺

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2XCH₃CO.CoA + 2NADH + 2H⁺ + 2CO₂

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• _{Pyruvate dehydrogenase enzyme consists of}

_{three different enzymes and five different coenzymes}

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Pyruvate dehydrogenase complex consist of three distinct enzymes, such as

1. Pyruvate dehydrogenase

2. Dihydrolipoyil transacetylase

3. Dihydrolipoyil dehydrogenase and five different coenzymes, TPP (Thymine Pyro Phosphate), NAD1, FAD, CoA and lipoate.

3. Krebs cycle

Significance of Krebs cycle

• It provides energy in the form ATP
• It provides carbon skeleton
• Intermediates used for amino acid, protein and nucleic acid metabolism
• Succinyl CoA is raw material for synthesis of chlorophyll, cytochrome, phytochrome .
• a ketoglutarate and oxaloacetate involved in amino acid formation be reductive amination
• Acts as metabolic sink.

Alternative substrates for Respiration

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• Amphibolic pathway

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Electron transport chain

Electron transport chain

1. Complex –I

NADH dehydrogenase

2. Complex-II

Succinic dehydrogenase

3. Complex –III

Cyt-bc₁

4. Complex –IV

Cyt-c oxidase

Peter Mitchel’s Chemiosmotic theory

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Complex I NADH dehydrogenase

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• FMN and Non heme iron sulphur protein
• Passing electrons and H⁺ from mitochondrial NADH to UQ(internal NADH dehydrogenase)
• In plants additional (External) NADH dehydrogenase is present

Complex II Succinic dehydrogenase

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• FAD and Non heme iron sulphur protein
• Receives electrons and protons from succinate converted into fumarate and passes to UQ.

Peter Mitchel’s Chemiosmotic theory

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Complex III Cytochrome bc₁

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• Passing electrons from reduced UQ(ubiquinol) to Cyt c through Cyt bc₁ complex
• Cyt c found in outer surface of inner membrane
• Cyt c act as mobile carrier between complex III to complex IV

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Complex IV Cytochrome oxidase

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• It contains two copper centre and cytochrome a

and a3

• It is terminal oxidase and reduce ½ O₂ to H₂O

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Peter Mitchel’s Chemiosmotic theory

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Oxidative phosphorylation

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Transfer of electrons from NADH to oxygen via Complex I to IV coupled to synthesis of ATP from ADP and Pi .

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Net products gained during aerobic Respiration

Net products gained during aerobic Respiration-Recent view

Electron transport chain inhibitors

• 2,4 DNP(Dinitrophenol)
• Cyanide
• Rotenone
• Oligomycin

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Respiratory Quotient(RQ)

In succulents

• Carbohydrate is partially oxidised to organic acid as malic acid
• O₂ is consumed but CO₂ is not released
• RQ value will be zero

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Some other substance RQ value

Proteins : 0.8-0.9

Oleic acid : 0.71

Tartaric acid : 1.6

Oxalic acid : 4.0

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Anaerobic Respiration

Fate of glucose in HMP shunt and glycolysis

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Starch

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Glucose

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Ribulose-5-phosphate pyruvic acid

Pentose phosphate pathway(HMP Shunt)

Evolution of Respiration

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