For UG and PG (Botany) students

1. RESPIRATION IN PLANTS
Dr. Vishal R. Marathe
Assistant Professor in Botany,
N. E. S. Science College, Nanded (Maharashtra)
Email ID: dr.vishalmarathe@gmail.com
Image source: www.google.com

2. INTRODUCTION
 The process in which complex organic substances like
carbohydrates, proteins, fats were broken down to release
energy, CO2 and Water.
 In many ways, respiration is opposite of photosynthesis.
 It helps plants to produce their own food to survive and to
create energy.
 Plants breathe for 24 X 7.
 They consume O2 and released CO2
 Plants produces more amount of O2 than they consume
during respiration
 Plants need energy for their growth and development,
reproduction, absorption of nutrients, healing damage
tissues etc. 2

3. One molecule of Glucose on complete oxidation
yields 686 kcal (kilocalories) of energy
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4. Types of Respiration
1. Aerobic Respiration:
 This type of respiration leads to a complete oxidation of stored
food (organic substances) in the presence of oxygen, and releases
carbon dioxide, water and a large amount of energy present in
respiratory substrate.
 Such type of respiration is generally found in higher organisms.
 The overall equation is:
C6H126O2 6CO2 + 6H2O + Energy
 Occus in three stages: 1) Glycolysis, 2) Citric Acid cycle and 3)
Electron Transport system
Enzymes
oxidation (2870 KJ) or (686 K cal)
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5. What happens when Oxygen is
not available?
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6. 2. Anaerobic respiration:
 occurs in complete absence of oxygen.
 It occurs in many tissues of higher plants, seeds in storage, fleshy
fruits, and succulent plants, such as cacti temporarily take to a kind
of respiration, generally occurs in lower organisms like bacteria
and fungi.
 This results in incomplete oxidation of stored food and formation
of carbon dioxide and ethyl alcohol, and sometimes also various
organic acids, such as malic, citric, oxalic, tartaric, etc.
 Very little energy is released
 The equation:
C6H126O2 2C2H5OH + 2CO2 + Energy
 This process of oxidation in microbes is known as fermentation.
 It is quite similar to anaerobic respiration in case of higher plants.
(247 KJ) or (28 K cal)
Enzymes
Fermentation
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7. Anaerobic Cellular Respiration
In anaerobic cellular respiration, the only step of
this process that occurs is glycolysis.
Glycolysis
Electron
Transport
System
Kreb Cycle
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8. Types of Respiration
Anaerobic Respiration Aerobic Respiration
Occurs in absence of oxygen Occurs in presence of oxygen
Occurs at cells cytoplasm (cytosol) Occurs at cells’ Mitochondria
Yields small amount of ATP (2
Molecules) per molecule of glucose
Yields large amount of ATP (38
Molecules) per molecule of glucose
Energy released in small quantity Energy released in large quantity
Respiratory substrate (Glucose) is
partially oxidised
Respiratory substrate (Glucose) is
completely oxidised
Final products are Lactic acid/ Ethyl
alcohol, CO2 and 2 ATP
Final products are CO2 , H2O and 38
ATP
Involves fermentation of pyruvate to
lactate in Muscle cells and Co2 &
Ethanol in plants and yeast
Does not involves fermentation
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9. Image source: www.google.com
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10. Fermentation
 Derived from the Latin verb ‘fervere’ meaning ‘to boil’
 Louis Pasteur in the 19th century used the term
 Traditional fermentation technology is more than 3000
years old
 It is supposed to have evolved first and is considered the
most ancient pathway for obtaining energy.
 Process by which the living cell is able to obtain energy
through the breakdown of glucose and other simple
sugar molecules without requiring oxygen
 Fermentation results in the production of energy in the
form of two ATP molecules, and produces less energy
than the aerobic process of cellular respiration .
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11. 1. Alcoholic fermentation
 Yeast cells obtain energy under anaerobic conditions
called alcoholic fermentation.
 used in baking and brewing for centuries.
 It is identical to glycolysis except for the final step.
 In this, pyruvic acid is broken down into ethanol and
carbon dioxide.
 The last enzyme of glycolysis, lactate dehydrogenase, is
replaced by two enzymes in alcoholic fermentation.
 These two enzymes, Pyruvate decarboxylase and
alcoholic dehydrogenase, convert pyruvic acid into
carbon dioxide and ethanol in alcoholic fermentation.
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12. Alcohol Fermentation
Pyruvate
decarboxylase
Alcoholic dehydrogenase
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13. 2. Lactic Acid Fermentation
In this, the pyruvic acid from glycolysis is
reduced to lactic acid by NADH, which is
oxidized to NAD+.
This commonly occurs in muscle cells.
It allows glycolysis to continue by ensuring that
NADH is returned to its oxidized state (NAD+).
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14. Image source: www.google.com
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15. Importance of fermentation process
 Commercially important fermentations for the
production of microbial cells (or biomass), microbial
enzymes, microbial metabolites, recombinant products
 Lactic acid and lactate from many bacteria, fungi,
protists, and animals cells (muscle cells in the body)
 Production of ethyl alcohol from yeast and plant cells
 Food products: from milk (yogurt, kefir, cheeses), fruits
(wine, vinegar), vegetables (pickles, soy sauce)etc.
 Industrial chemicals: (solvents: acetone, butanol, ethanol,
enzymes, amino acids)
 Specialty chemicals (vitamins, pharmaceuticals)
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