RESPIRATION IN PLANTS

K C MEENA

PGT BIOLOGY

DEFINATION

• In physiology, respiration is defined as the transport of oxygen from the outside air to the cells within tissues, and the transport of carbon dioxide in the opposite direction.
•  Cellular respiration: the metabolic process by which an organism obtains energy by reacting oxygen with glucose to give water, carbon dioxide and ATP (energy). 
• Breathing (which in organisms with lungs is called ventilation and includes inhalation and exhalation) is a part of physiologic respiration.

RESPIRATION

• The phenomenon of release energy by oxidation of various organic molecules for cellular use is known as respiration.
• The compound that are oxidisedduring tis process are known as respiratory substrate.

2870 kj

247 KJ

RESPIRATORY QUOTIENT

• RQ

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• RQ for carbohydrates will be 1

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• fats are used in respiration, the RQ is less than 1

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• RQ for Protien about 0.9
• RQ for Organic Acids more than 1
• RQ for anarobic Respiration-

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• RQ = 2 CO_{2 = INFINITY}
• 0O₂

STEPS IN CELLULAR RESPIRATION

• There are mainly four steps involve in cellular respiration

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• GLYCOLYSIS
• LINK REACTION
• KREB CYCLE
• ELECTRON TRANSPORT SYSTEM

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GLYCOLYSIS�(glyco = sugar; lysis = breaking)

• The scheme of glycolysis was given by Gustav Embden, Otto Meyerhof, and J. Parnas, and is often referred to as the EMP pathway
• Glycolysis occurs in the cytoplasm of the cell and is present in all living organisms
• break glucose down to form two pyruvates.
• 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
• 2 NADH = 3 ATP
• SO total ATP release in Glycolysis = 8

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The Preparatory Phase – in which ATP is consumed

The Pay Off Phase – in which ATP is produced.

GLYCOLSIS STEPS

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overall process of glycolysis

The overall process of glycolysis is:

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Glucose + 2 NAD⁺ + 2 ADP + 2 P_i →

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2 Pyruvate + 2 NADH + 2 H⁺ + 2 ATP + 2 H₂O

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LINK REACTION

• This reaction is very common in most organisms as a link between glycolysis and the citric acid cycle. In organisms that perform aerobic respiration the reaction is usually catalyzed by the pyruvate dehydrogenase complex .
•  Takes place exclusively inside the mitochondrial matrix,
• The acetyl CoA then enters a cyclic pathway, tricarboxylic acid cycle,

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Tricarboxylic Acid Cycle

• Elucidated by the British biochemist Hans Krebsin 1937
• This is also known as ticarboxlic acid cycle(TCA Cycle) or Kreb Cycle.
• For this pioneering workHans Krebs was awarded the coveted Nobel Prize in 1953.
• The TCA cycle starts with the condensation of acetyl group with oxaloacetic acid (OAA) and water to yield citric acid

GLUCOSE

GLYCOLYSIS

LINK REACTION

TOTAL ATP FORMATION�

Electron Transport Chain (ETS)�

• NADH2 and FADH2 are oxidised to release the energy stored in them in the form of ATPs.
• Electrons are passed from one carrier to another, and finally to oxygen,resulting in the formation of water.
• Oxidation of 1 NADH produces 3 ATPs.
• Oxidation of 1 FADH2 produces 2 ATPs.

Oxidative Phosphorylation

• Respiratory Balance Sheet

Glucose + 6O2 + 36ADP + 36Pi → 6CO2 + 6H2O + 36ATP

Amphibolic Pathway�

Respiratory Quotient (RQ)�

• It is the ratio of the volume of CO2 evolved to the volume of O2 consumed during respiration.
• RQ = 1 (When carbohydrate is used as substrate)
• C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy
• RQ is less than 1 for fats.
• 2 C51 H98 O6 +145 O2 - --> 102CO2 + 98H2O + Energy
• RQ = 102 CO2
• -------------- = 0.7
• 145 O2
• RQ is 0.9 for proteins.
• RQ is more than 1 for organic acids.
• RQ is infinite in case of anaerobic resp. because CO2 is evolved but O2 is not consumed.