This is the citric acid cycle that is explained in a very easy and good manner,will be understood in one time only.

2. Introduction
 The citric acid cycle — also known as the
tricarboxylic acid cycle (TCA cycle), the Krebs
cycle — is a series of enzyme-catalysed chemical
reactions, which is of central importance in all
living cells that use oxygen as part of cellular
respiration.

3. Introduction

4. Introduction

5. Introduction

6. Introduction

7. Introduction

8. Introduction

11. Net reaction of citric acid cycle
• The reactions of the
citric acid cycle
oxidize acetyl-CoA’s
acetyl group to two
molecules of carbon
dioxide.
• During the reaction
cycle, electrons are
transferred from
acetyl-CoA to
electron carriers.

12. • Once an electron carrier accepts an electron, it is referred to
as “reduced.”
• Ultimately, reduced electron carriers participate in
downstream reaction pathways that generate ATP

17. • In the case of higher eukaryotes, a
cell most commonly acquires
glucose in two ways—by breaking
down complex carbohydrates into
simple sugars and by mobilizing
glucose from glycogen, the body’s
storage system for glucose.
• In the cytosol, glucose is broken
down to two, 3-carbon pyruvate
during glycolysis.
• Pyruvate is transported across the
mitochondrial membrane where
it is broken down to a 2-carbon
compound called acetyl-CoA plus
carbon dioxide.

18. • Remaining carbon skeleton is broken down to acetyl-CoA or
to pyruvate, which is then converted to acetyl-CoA.
• Alternatively, a citric acid cycle intermediate such as α-
ketoglutarate may result
• An amino acid consists of an
amino and a carboxyl group at
opposite ends, plus an attached
side chain.
• Amino group of an amino acid is
removed in a deamination
reaction

19. • Fatty acids - carboxylic acid with a long, hydrocarbon tail
• Palmitate is an example of a sixteen-carbon fatty acid

20. • When a cell’s metabolic needs increase, free fatty acids enter
the mitochondrion where the degradative reactions called β
oxidation ensue.
• A fatty acid shortened by two carbon atoms plus a free acetyl-
CoA molecule results from each round of b oxidation.