Carbohydrate metabolism involves the breakdown of carbohydrates like glucose to produce energy. There are three main types of carbohydrates: monosaccharides like glucose and fructose, oligosaccharides containing a few sugar units like sucrose, and polysaccharides like starch, glycogen, and cellulose. Glycolysis is the first step of carbohydrate metabolism, breaking down glucose into pyruvate while producing a small amount of ATP. Glycolysis occurs in ten steps through two phases and produces two ATP and two NADH per glucose molecule broken down. The pyruvate produced can then be used for cellular respiration to produce more energy.

1. Carbohydrate Metabolism
Presented by
Prof.(Dr.)Kirtimaya Mishra

2. Function of carbohydrate

3. Carbohydrate, (C-H2O)n = “Carbon + Water”
What are Carbohydrates (saccharides)?
Carbohydrate is an organic compound with the
general formula Cm(H2O)n, which consists of carbon,
hydrogen and oxygen, the last two in the 2:1 atom ratio.
Carbohydrates are hydrates of carbon, hence their name.

4. Where are Carbohydrates?
Function of Carbohydrates ?

5. Upland cotton produces the most widely used
natural fibers, cellulose (polysaccharide)
Cellulose:
 the most abundant organic
compounds in the biosphere
 1015 kg of cellulose is
synthesized and degraded
on earth each year

6. Carbohydrates in food are important
sources of energy.

7. Cell wall
Energy sources
Energy sources and structural elements

8. Energy sources and structural elements

9. Bioactive substance——Glycoproteins and Glycolipids

10. Function of Carbohydrates
 Source of energy
 Structure (cotton fibers: cellulose )
 Building blocks
 Cellular recognition

11. The classification of carbohydrates
（Saccharides ）

12. • The generic name of the simplest carbohydrates.
• Monosaccharides can not be hydrolysised to give
smaller carbohydrates.
1 Monosaccharide

13.  Triose 3 carbons
 Tetrose 4 carbons
 Pentose 5 carbons
 Hexose 6 carbons
 Heptose 7 carbons
Monosaccharides can be classified
according to the number of carbons:

14. Important hexose :
Glucose , fructose , galactose, mannose

15.  Pentose：
D-Ribose

16. 2 Oligosaccharide
Any molecule that contains a small number (2 to
about 20) of monosaccharide residues
connected by glycosidic linkages.

17. Maltose
Oligosaccharide
1 4

18.  Sucrose
It is formed by plants
but not by animals.
2
1
1 2

19.  Lactose
Lactose occurs naturally in milk but rarely in plants.

20. Cellobiose

21. 3 Polysaccharide
 An alternative name for glycan ;
 Any linear or branched polymer consisting of
monosaccharide residues. Important polysaccharides
include glycogen, starch and cellulose .

22. Starch
 Energy store of plants

23.  Amylose
It can be made of several thousand glucose units.
In amylose, the 1st carbon on one glucose
molecule is linked to the 4th carbon on the next
glucose molecule (α(1→4) bonds).
Amylose is soluble in water.

24.  Amylopectin
Glucose units are linked in a linear way with α(1→4)
glycosidic bonds. Branching takes place with α(1→6)
bonds occurring every 24 to 30 glucose units.
It is not soluble in water.

25. Muscle:
energy (ATP)
production.
Liver: balance
blood glucose
levels.
Glycogen
Glycogen is found mainly in the
liver and skeletal muscle.

26. Cellulose
 A linear, unbranched β l-4 glucan molecular

27. Glycolysis

28. In glycolysis, a molecule of glucose is broken down in a
series of enzyme-catalyzed reactions to yield two
molecules of the three-carbon compound pyruvate .
During the sequential reactions of glycolysis, some of
the free energy released from glucose is conserved in
the form of ATP and NADH.

29.  First stage of carbohydrate metabolism.
 Glycolysis was first discovered by Gustav Embden and
Otto Meyerhof and Parnus. Glycolysis is named as
EMP
 Simple sugars are broken down to pyruvate
 No oxygen needed.
 All life uses this process.
 There are 10 steps in glycolysis.

30. 1 The Reaction of the glycolysis (Two Phases)
 Preparatory phase（step①-⑤）：
Phosphorylation of glucose and its
conversion to glyceraldehyde 3-
phosphate
 Payoff phase（step⑥-⑩）：
Oxidative conversion of glyceraldehyde 3-
phosphate to pyruvate and the coupled
formation of ATP and NADH

31. (1) Phosphorylation of Glucose
or glucokinase
Transfer of a phosphoryl group from ATP to glucose

32. (2) Isomerization :Conversion of Glucose 6-
Phosphate to Fructose 6-Phosphate

33. (3) Phosphorylation of Fructose 6-Phosphate to Fructose
1,6-Bisphosphate

34. (4) Cleavage of Fructose 1,6-Bisphosphate

36. （5）Interconversion of the Triose Phosphates

37. (6) Oxidation of Glyceraldehyde 3-Phosphate to
1,3-Bisphosphoglycerate
Oxidation and phosphorylation, yielding a high-energy
mixed-acid anhydride

38. (7) Phosphoryl Transfer from 1,3-bisphosphoglycerate
to ADP
Transfer of a high-energy phosphoryl group to ADP, yielding ATP

39. (8) Conversion of 3-Phosphoglycerate to 2-Phosphoglycerate

40. (9) Dehydration to an energy-rich enol ester
PEP

41. (10) Transfer of the Phosphoryl Group from
Phosphoenolpyruvate to ADP
Transfer of a high-energy phosphoryl group to ADP, yielding ATP

44.  For each molecule of glucose that passes
through the preparatory phase (a), two
molecules of glyceraldehyde 3-phosphate are
formed; both pass through the payoff phase
(b), Pyruvate is the end product of the
second phase of glycolysis.

45.  For each glucose molecule, two ATP are
consumed in the preparatory phase and four
ATP are produced in the payoff phase, giving
a net yield of two ATP per molecule of
glucose converted to pyruvate.

46.  The glycolytic breakdown of glucose is the
sole source of metabolic energy in some
mammalian tissues and cell types
(erythrocytes, renal medulla, brain, and
sperm, for example).
 Many anaerobic microorganisms are
entirely dependent on glycolysis.

47. Significance
Glycolysis is the first metabolic pathway of cellular respiration to
produce energy in the form of ATP.
It represents the important set of biochemical catabolic reactions in
all living cells.
It is the only source of energy in erythrocytes.
The pyruvate (3-c) is produced as end product of gycolysis that is
available in the cell for further respiratory breakdown or for use in
various other metabolic process.
The pathways provides carbon skeletons for synthesis of non-
essential amino acids as well as glycerol phosphate pathway.
Most of the reaction steps are reversible which are used for
gluconeogenesis.

48. Thank you