One of the key pathways in Cellular respiration- Citric acid cycle
Citric acid cycle – The biochemical hub of the cell
Mechanism of cellular respiration
The energy stored in the organic molecules of food ultimately comes from
the sun. During process of respiration, the whole of energy contained in respiratory
substrates is not released all at the time. It is released slowly in several steps
of reactions controlled by different enzymes.
As we know, important life processes,
such as synthesis of proteins, fats and carbohydrates, require a certain expenditure
of energy. Where does this energy come from, how is it stored, and how is it made
available to the living cell, are some of the questions, which are to be answered
by process of respiration. The reaction that occurs in common respiration of glucose
may be summed up as follows:
Glucose + Oxygen Carbon Dioxide + Water + Energy
In this chapter, we consider how cells harvest the chemical energy stored in organic
molecules and use it to generate ATP, the molecule that drives most cellular work.
After presenting some basics about respiration, we will focus on the three key pathways
of respiration: Glycolysis, the Citric acid cycle, and oxidative phosphorylation.