Glycolysis is the metabolic pathway that converts glucose into pyruvate, producing ATP and NADH in the process. It consists of two phases: the preparatory phase where glucose is broken down into two molecules of glyceraldehyde-3-phosphate, and the energy-generating phase where those molecules are converted into two pyruvate molecules while producing ATP and NADH. The net result is the production of two ATP per glucose molecule. Glycolysis was elucidated over the course of the 19th and early 20th centuries through the work of many scientists including Pasteur, Buchner, Meyerhof, and Embden.

2. Glycolysis
KASHIF ALI 2K18/BTCH/41 (GROUP LEADER)
AKASH TUNIO 2K18/BTCH/12
SARMAD ALI 2K18/BTCH/68
Presented BY (ASK GROUP):
Prepared BY: KASHIF RANDHAWA
UNIVERSITY OF SINDH, JAMSHORO
DEPARTMENT OF BIOTECHNOLOGY
Assigned By:
MAM FAIZA MAKHDOM

3. Historical Perspective
The pathway of glycolysis as it is known today took almost 100 years to fully discover. The
combined results of many smaller experiments were required in order to understand the
pathway as a whole.
The first steps in understanding glycolysis began in the nineteenth century with the wine
industry. For economic reasons, the French wine industry sought to investigate why wine
sometime turned distasteful, instead of fermenting into alcohol.
French scientist Louis Pasteur researched this issue during the 1850s, and the results of his
experiments began the long road to elucidating the pathway of glycolysis.

4. Historical Perspective (cont…)
While Pasteur's experiments were groundbreaking, insight into the component steps of
glycolysis were provided by the noncellular fermentation experiments of Eduard Buchner during
the 1890s. Buchner demonstrated that the conversion of glucose to ethanol was possible using a
non-living extract of yeast (due to the action of enzymes in the extract).
Arthur Harden and William Young along with Nick Sheppard determined, in a second
experiment, that a heat-sensitive highmolecular-weight subcellular fraction (the enzymes) and a
heat-insensitive low-molecular-weight cytoplasm fraction (ADP, ATP and NAD+ and other
cofactors) are required together for fermentation to proceed.
In the 1920s Otto Meyerhof was able to link together some of the many individual pieces of
glycolysis discovered by Buchner, Harden, and Young.
With all of these pieces available by the 1930s, Gustav Embden proposed a detailed, step-by-
step outline of that pathway we now know as glycolysis.

5. What is glycolysis?
Glycolysis (from glycose, an older term for glucose + lysis degradation) is the metabolic
pathway that converts glucose C6H12O6, into pyruvate, CH3COCOO− + H+.
The free energy released in this process is used to form the highenergy molecules ATP
(adenosine triphosphate) and NADH (reduced nicotinamide adenine dinucleotide).
Glycolysis is a sequence of ten enzyme-catalyzed reactions. Most monosaccharides, such as
fructose and galactose, can be converted to one of these intermediates.
The intermediates may also be directly useful. For example, the intermediate dihydroxyacetone
phosphate (DHAP) is a source of the glycerol that combines with fatty acids to form fat.
Glycolysis carried out in the cytosol of cells, it is unique, in that it can function either
aerobically or anaerobically, depending on the availability of oxygen and the electron transport
chain.

6. Overview:
Glycolysis consists of two phases:
• In the first phase, a series of five reactions, glucose is broken down to two molecules of
glyceraldehyde-3phosphate.(preparatory phase)
• In the second phase, five subsequent reactions convert these two molecules of glyceraldehyde-
3phosphate into two molecules of pyruvate.(energy generating phase)
• Phase 1 consumes two molecules of ATP.
• The later stages of glycolysis result in the production of four molecules of ATP .
• The net is 4 –2 = 2 molecules of ATP produced per molecule of glucose.
• Most of the details of this pathway (the first metabolic pathway to be elucidated) were worked out
in the first half of the 20th century by the German biochemists Otto Warburg, G. Embden, and O.
Meyerhof.
• In fact, the sequence of reactions in is often referred to as the Embden-Meyerhof pathway.

7. Reactions:
The overall reaction of glycolysis which occurs in the cytoplasm is represented simply as:
◦ C H O + 2 NAD + 2 ADP + 2 P —–> 2 pyruvic acid, (CH (C=O)COOH + 2 ATP + 2 NADH + 2 H

9. Perparatory Phase
Step 1: Phosophyrlation
 The first step in glycolysis is the conversion of D-glucose into glucose-6-phosphate. The
enzyme that catalyzes this reaction is hexokinase.

10. Perparatory Phase (cont…)
Step 2: Isomerization
 The second reaction of glycolysis is the rearrangement of glucose 6-phosphate (G6P) into
fructose 6-phosphate (F6P) by glucose phosphate isomerase (Phosphoglucose Isomerase).

11. Perparatory Phase (cont…)
Step 3: Phosphorylation
• Phosphofructokinase, with magnesium as a cofactor, changes fructose 6-phosphate into
fructose 1,6-bisphosphate.

12. Perparatory Phase (cont…)
Step 4: Cleavage
• The enzyme Aldolase splits fructose 1, 6-bisphosphate into two sugars that are isomers of each
other. These two sugars are dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3 phosphate
(GAP).

13. Perparatory Phase (cont…)
Step 5: Isomerazation
• The enzyme triophosphate isomerase rapidly inter- converts the molecules
dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3-phosphate (GAP). Glyceraldehyde
phosphate is removed / used in next step of Glycolysis.

14. Energy generating phase
Step 6:Oxydation
• Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) dehydrogenates and adds an
inorganic phosphate to glyceraldehyde 3-phosphate, producing 1,3-bisphosphoglycerate.

15. Energy generating phase (cont…)
Step 7: Phosphorylation
• Phosphoglycerate kinase transfers a phosphate group from 1,3-bisphosphoglycerate
to ADP to form ATP and 3-phosphoglycerate.

16. Energy generating phase (cont…)
Step 8: Isomerization
• The enzyme phosphoglycero mutase relocates the P from 3- phosphoglycerate from
the 3rd carbon to the 2nd carbon to form 2-phosphoglycerate.

17. Energy generating phase (cont…)
Step 9: Dehydration
• The enzyme enolase removes a molecule of water from 2-phosphoglycerate to form
phosphoenolpyruvic acid (PEP).

18. Energy generating phase (cont…)
Step 10: Phosphorylation
• The enzyme pyruvate kinase transfers a P from phosphoenolpyruvate (PEP) to ADP to
form pyruvic acid and ATP Result in step 10.

19. Net gain of Energy during Glycolysis
Steps 1 and 3 = – 2ATP
Steps 7 and 10 = + 4 ATP
Net “visible” ATP produced = 2