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A Handbook of Biology
STËPS ØF GLÝÇØLÝSÏS
It includes 10 steps under the control of different enzymes.
ATP is utilized at 2 steps:
–
In the conversion of glucose into glucose 6-phosphate. In the
conversion of fructose 6-phosphate to fructose 1, 6-bisphosphate.
–
Fructose 1, 6-bisphosphate is split into dihydroxyacetone phosphate
and 3- phosphoglyceraldehyde (PGAL).
PGAL is oxidized and with inorganic phosphate get converted to 1, 3-
bisphosphoglycerate (BPGA). During this, 2 redox equivalents (2 H atoms)
are removed from PGAL and transferred to NAD+ forming NADH + H+.
BPGA becomes 3-phosphoglyceric acid (PGA) yielding energy. This
energy is trapped by the formation of ATP.
ATP is also formed when PEP converts to pyruvic acid.
In glycolysis, 4 ATP molecules are directly synthesized from one glucose
molecule.
Pyruvic acid is the key product of glycolysis
Metabolic fate of pyruvate depends on the cellular need.
THËRË ÅRË THRËË MÅJØR WÅÝS :
Lactic acid fermentation
Alcoholic fermentation
Aerobic respiration
(Krebs’ cycle)
FËRMËÑTÅTÏØÑ (ÅÑÅËRØBÏÇ RËSPÏRÅTÏØÑ)
It is the incomplete oxidation of glucose under anaerobic condition.
It occurs in many prokaryotes and unicellular eukaryotes, and in
germinating seeds.
It is of 2 types: