Glycolysis is a series of enzymatic reactions that breaks down glucose into pyruvate, generating a small amount of ATP through substrate-level phosphorylation. It occurs in the cytoplasm and consists of two phases: the preparatory phase uses two ATP molecules to phosphorylate and split glucose into two three-carbon glyceraldehyde-3-phosphate molecules, while the payoff phase generates four ATP molecules from the breakdown of the two glyceraldehyde-3-phosphate molecules into two pyruvate molecules, resulting in a net production of two ATP per glucose molecule. Glycolysis also produces two NADH molecules that are used in the electron transport chain to generate additional ATP.

1. GLYCOLYSIS
PRESENTED BY:
ATUL TRIPATHI
M.Sc Biotechnology
Govt.TRS clg Rewa (m.p.)

2. METABOLISM
 Metabolism is a series of inter connected chemical reaction occuring
within a cell and the chemical compounds involved in it are termed as
metabolities.
 Metabolism is the process by which your body converts what you eat and drink into
energy.
 In this process glycolysis is the part of it.

3. GLYCOLYSIS
 Glycolysis comes from a merger of two greek word:Glysks-sweet
 Lysis-breakdown
 It is also known as EMBDEN MEYERHOF-PARNAS.
 DEFINITION:
Glycolusis is defined as the sequence of reaction converting
glucose to pyruvate Or lactate, with production of ATP(Adinosine-tri-Phoaphate).
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4. Features of glycolysis:
 Glycolysis has several important features:
1. It breaks down one molecule of glucose, a 6-carbon molecule, into two molecules of
pyruvate, a 3-carbon molecule, in a controlled manner by ten or more reactions.
The oxidation of glucose is controlled so that the energy in this molecule can be
used to manufacture other high energy com
2. It makes a small amount of ATP, a process known as substrate-level
phosphorylation. For each glucose molecule that is broken down by glycolysis, there
is a net gain of two molecules of ATP.
3. It makes NADH (reduced nicotinamide adenine dinucleotide), a high energy
molecule which can be used to make ATP in the electron transfer chain (see below).
For each glucose molecule that is broken down by glycolysis, there is a net gain of
two molecules of NADH.
4. It makes compounds which can be used to synthesize fatty acids. In particular,
some of the carbohydrate intermediates of glycolysis are used by other enzymatic
reactions to synthesize fatty acids, the major constituents of lipids, important energy
storage molecules.

5. Reaction of glycolysis
The breakdown of glucose to 2 moleculeas of pyruvate is brought about by sequence
of 10 reactions which is divided into 2 phase:
1. Preparatory phase
2. Payoff phase
 PREPARATORY PHASE:
1. It consists of the 1st 5 step of glycolysis in which the glucose is enzymatically
phosphorylated by ATP to yeild Fructose-1, 6 biphosphate.
2. This fructose-1, 6, biphosphate is then split in half to yeild 2 molecules of 3
carbon containing glyceraldehyde-3, phosphate/dihydroxy-acetone-phosphate.
Thus the first phase results in cleavage of hexose chain, this cleavage requires an
investment of 2 ATP molecules to activate the glucose mole and prepare it for its
cleavage into 3-carbon compound.

7. Payoff phase:
1. This phase constitutea the last 5 reaction of glycolysis.
2. Thsi phase makes the release of ATP molecules during conversrion of
glyceraldehyde-3-phosphate to 2 moles of pyruvate.
3. Here 4 molese of ADP are phosphorylated to ATP. Although 4 moles of ATP are
formed, the net result is only 2 moles of ATP/moles of ATP are utilized in
phase 1.

9. Stepwise explanation:
 Step 1
 The enzyme hexokinase phosphorylates or adds a phosphate group to glucose in a cell's cytoplasm. In the
process, a phosphate group from ATP is transferred to glucose producing glucose 6-phosphate or G6P. One
molecule of ATP is consumed during this phase.
 Step 2
 The enzyme phosphoglucomutase isomerizes G6P into its isomer fructose 6-phosphate or F6P. Isomers
have the same molecular formula as each other but different atomic arrangements.
 Step 3
 The kinase phosphofructokinase uses another ATP molecule to transfer a phosphate group to F6P in order
to form fructose 1,6-bisphosphate or FBP. Two ATP molecules have been used so far.
 Step 4
 The enzyme aldolase splits fructose 1,6-bisphosphate into a ketone and an aldehyde molecule. These sugars,
dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3-phosphate (GAP), are isomers of each other.
 Step 5
 The enzyme triose-phosphate isomerase rapidly converts DHAP into GAP (these isomers can inter-
convert). GAP is the substrate needed for the next step of glycolysis.

10. • Step 6
The enzyme glyceraldehyde 3-phosphate dehydrogenase (GAPDH) serves two
functions in this reaction. First, it dehydrogenates GAP by transferring one of its hydrogen
(H⁺) molecules to the oxidizing agent nicotinamide adenine dinucleotide (NAD⁺) to form
NADH + H⁺.
Next, GAPDH adds a phosphate from the cytosol to the oxidized GAP to form 1,3-
bisphosphoglycerate (BPG). Both molecules of GAP produced in the previous step
undergo this process of dehydrogenation and phosphorylation.
• Step 7
The enzyme phosphoglycerokinase transfers a phosphate from BPG to a molecule
of ADP to form ATP. This happens to each molecule of BPG. This reaction yields two
3-phosphoglycerate (3 PGA) molecules and two ATP molecules.
• Step 8
The enzyme phosphoglyceromutase relocates the P of the two 3 PGA molecules
from the third to the second carbon to form two 2-phosphoglycerate (2 PGA)
molecules.
• Step 9
The enzyme enolase removes a molecule of water from 2-phosphoglycerate to form
phosphoenolpyruvate (PEP). This happens for each molecule of 2 PGA from Step 8.
• Step 10
The enzyme pyruvate kinase transfers a P from PEP to ADP to form pyruvate and
ATP. This happens for each molecule of PEP. This reaction yields two molecules of
pyruvate and two ATP molecules.