Glycolysis
WALT
• Glycolysis takes part in the cytosol of the
cell
• Glucose is oxidised to pyruvate by a series
of reactions
• It produces a net of 2 ATP per molecule of
glucose and 2 NADH
Glycolysis
Glycolysis is a series of biochemical reactions by
which a molecule of glucose is oxidised to two
molecules of pyruvic acid.
Glycolysis serves two principal functions: generation of
high-energy molecules (ATP and NADH), and
production of a variety of six- or three-carbon
intermediate metabolites.
Glycolysis is one of the most universal metabolic
processes known, and occurs (with variations) in many
types of cells in nearly all types of organisms.
NAD and FAD
•A couple of other molecules are important as
electron-carrying molecules.
•Nicotinamide Adenine Dinucleotide (NAD) a
coenzyme derived from the vitamin niacin, or
B3. NAD can be reduced to NADH for redox
reactions
•Flavin-Adenine Dinucleotide (FAD) another
coenzyme, this one derived from riboflavin /
B2 serves a similar function. FAD can be
reduced to FADH2 and carry hydrogens /
electrons between reactions
Overview of Glycolysis
Glucose
Glycolysis
in
2 ATP
2 NADH
cytoplasm
2 NADH
2 Pyruvate
4 ATP
To mitochondria
2 Pyruvate
ATP
For use in the cell for work
Sugars are not very reactive
so to start the process 2ATP’s
are used to add 2 phosphates
to glucose in a series of three
reactions generating Fructose
1,6 - bisphosphate
The phosphorylated sugar then breaks down into
two 3 carbon molecules, one is glyceraldehyde
phosphate the other is quickly converted into
glyceraldehyde phosphate
1st stage of glycolysis
2 ATP
2 ADP + 2 Pi
Glycolysis
• The two molecules of glyceraldehyde 3-phosphate
will now go through each of the remaining steps in
glycolysis producing two molecules of each
product.
• As each of the two molecules of glyceraldehyde 3phosphate are oxidized, the energy released is
used to add an inorganic phosphate group to ADP
to form two molecules of ATP per GALP ( 4 in total)
. During these oxidations a molecule of NAD+ is
reduced to form NADH + H+ (2 in total)
2nd Stage of Glycolysis
2 ADP + 2 Pi
2ATP
NADP
2 ADP + 2 Pi
NADP
2 NADP
2ATP
2 NADP
The Link Reaction
• Pyruvate easily enters the matrix of the
mitochondria where it enters a circular pathway
(Krebs cycle) which occurs within the matrix of
the mitochondria.
• The first step is to convert pyruvate into a twocarbon fragment, then attach it to another
coenzyme known as coenzyme A or CO-A.
• This is called the link reaction
• 2 molecules of NADH are also produced
The Link Reaction
Glycolysis
• Use all of the information today and the
text book pages 11,12 and 13 to draw out
the reactions of glycolysis with clear
explanations of what is happening at each
stage
• Hand in next lesson
•
• http://science.nhmccd.edu/biol/glylysis/glyl
ysis.html
In Animals
In the presence of oxygen pyruvate is transported into the mitochondria where it
enters the next major metabolic pathway for the production of ATP energy. The
citric acid cycle. Aerobic.
If there is no oxygen present then the pyruvate is converted to a substance called
lactate.