Question
Explain various steps involved in cellular respiration.
✓
Answer
Steps of cellular respiration:
i. Glycolysis: Glycolysis is the first step in cellular respiration. During glycolysis, glucose undergoes partial oxidation to form pyruvic acid. From 1 molecule of glucose, 2 molecules of pyruvic acid is formed.
ii. Aerobic or Anaerobic respiration:
• In the absence of oxygen pyruvic acid is converted into lactic acid or ethanol.
• Citric Acid Cycle: Under aerobic conditions, the pyruvic acid enters citric acid cycle NADH +$H ^{+}$ and FADH2 which enter into the ETS.
Pyruvic acid + $CoA + NAD ^{+} \xrightarrow{ Mg ^{2+}}$ Acetyl $CoA + NADH + H ^{+}$
iii. Electron Transport System (ETS) and Oxidative Phosphorylation
• Energy stored in $NADH + H ^{+}$ and FADH2 is utilised to form ATP. This is accomplished when they are oxidised through the electron transport system and the electrons are passed on to $O _2$ resulting in the formation of $H _2 O$.
• When the electrons pass from one carrier to another in the electron transport chain, they are coupled to ATP synthase for the production of ATP from ADP and inorganic phosphate.
i. Glycolysis: Glycolysis is the first step in cellular respiration. During glycolysis, glucose undergoes partial oxidation to form pyruvic acid. From 1 molecule of glucose, 2 molecules of pyruvic acid is formed.
ii. Aerobic or Anaerobic respiration:
• In the absence of oxygen pyruvic acid is converted into lactic acid or ethanol.
• Citric Acid Cycle: Under aerobic conditions, the pyruvic acid enters citric acid cycle NADH +$H ^{+}$ and FADH2 which enter into the ETS.
Pyruvic acid + $CoA + NAD ^{+} \xrightarrow{ Mg ^{2+}}$ Acetyl $CoA + NADH + H ^{+}$
iii. Electron Transport System (ETS) and Oxidative Phosphorylation
• Energy stored in $NADH + H ^{+}$ and FADH2 is utilised to form ATP. This is accomplished when they are oxidised through the electron transport system and the electrons are passed on to $O _2$ resulting in the formation of $H _2 O$.
• When the electrons pass from one carrier to another in the electron transport chain, they are coupled to ATP synthase for the production of ATP from ADP and inorganic phosphate.
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