This document provides an overview of carbohydrate metabolism. It begins with an introduction to carbohydrates and their classification. It then discusses specific carbohydrate metabolic pathways in more detail, including glycolysis, glycogenolysis, glycogenesis, the citric acid cycle, and the pentose phosphate pathway. It also covers topics like glycogen storage disorders, the role of these pathways in energy production, and their regulation of blood glucose levels. Clinical implications and examples are provided throughout.

1. V.Umakanth NaikV.Umakanth Naik
DBT-BIF-TRAINEEDBT-BIF-TRAINEE
Svims universitySvims university
TirupatiTirupati

2. Introduction
Classification of Carbohydrates
Glycolysis
Glycogenolysis
Glycogenesis
Citric acid cycle
Pentose phosphate pathway
Applied aspects
Regulation of Blood glucose

3. Nutrition is defined as “the sciencethe science
of how the body utilizes food toof how the body utilizes food to
meet requirements for developmentmeet requirements for development
growth, repair and maintenance”growth, repair and maintenance”

4. FATS
PROTEINS
VITAMINS
MINERALS
WATER
CARBOHYDRATES

5. In plants,
Carbondioxide+water
Glucose
(stored as starch or
converted to cellulose)
In Animals,
Fat + protein
carbohydrate

6. Glucose is a major carbohydrate
It is a major fuel of tissues
It is converted into other carbohydrates
 Glycogen for storage.
 Ribose in nucleic acids.
 Galactose in lactose of milk.
 They form glycoproteins & proteoglycans
 They are present in some lipoproteins (LDL) .
 Present in plasma membrane:glycocalyx.
 Glycophorin is a major intergral membrane glycoprotein
of human erythrocytes.

7. Most abudant organic molecules in nature.
Composition-carbon,oxygen,hydrogen
Also called as hydrates of carbon
Formula [CH20]n
Definiton;it is defined as polyhydroxy aldehydes or ketones
,compounds which produce them on hydrolysis .aslo called
as sugars
 soluble in water and sweet to taste.
Ex:glucose,fructose,sucrose,maltose etc.

8. Abundant dietary source of energy 4cal /g for all
organisms
Precursors for many organic compounds {fats,aa}.
Present in cell membrane as glycoproteins and
glycolipids .
Helps in cell growth,cell adhesion & fertilization.
Storage form of energy for immediate energy
demands [glucose is stored as glycogen]
In plants its is present as a cellulose (fiber content

9. Carbohydrates
Monosaccharides
Soluble in water.
Simple sugars
Sweet to taste
Formula Cn(H2o)
Disaccharides
Reducing free aldehydes r
keto group present :mal,lac
Non reducing:sucrose
Trisacharide
Oligosaccharides
Polysaccharide
Held together by
glycosidic bonds.
Homopolysacharide
Heteropolysacharide
Aldoses:CHO
GLU,Glycerade
hyde
Ketoses :C=O
Fructose,dhap

10. Depending on carbon
atoms
Depending on aldehyde or
ketone group
•Trioses: Glycerose-Aldo
Dihydroxyacetone-Ketone
•Tetroses Erythrose (A)
Erythrulose (K)
•Pentoses: Ribose (A)
Ribulose (K)
•Hexoses: Glucose (A)
Fructose (K)
•Aldoses
•Ketoses

11. •Disaccharides
•Maltose
•Sucrose
Oligosaccharides
•Maltotriose
Polysaccharides
•Linear - Starch
•Branched- Dextrin

12.  Stereoisomerism:same structural formula but different in
arrangement around one carbon atom .
Ex;D-glucose,l-glucose
 Enantiomers:mirror images of each other .
Ex:D-&L-glucose.
 Epimers:Two monosacharides differ from each other
around a single specific carbon atom .
Ex:glu,galactose around C11.
Mutarotation:specific optical rotation of aplha nd beta form
of D-glucose to an quilibrium mixture.
Aplha-d glucose:+112.2
Equilibrium mixture:+52.7
Beta d gluscose :+18.7

13. The entire spectrum of chemical reactions,
occuring in the living system are referred as
“Metabolism”.“Metabolism”.
Types of metabolic pathways
 Anabolic pathways: Protein synthesis.
 Catabolic Pathways: Oxidative phosphorylation.
 Amphibolic pathways: Citric acid cycle.

14. Food molecules simpler molecules
Amphibolic pathway
Anabolic Catabolic
Proteins, carbohydrates, CO2+H2O
lipids, nucleic acids etc.
2H
P

15. Metabolic pathways may be studied at different levels
of organisation.
 At tissue level
 At subcellular level

16. Overview of
Carbohydrate
Metabolism
Overview of
Carbohydrate
Metabolism

17. Glucose
Glucose-6-P
Pyruvate
Hexokinase
Pentose
Phosphate
Shunt
glycolysis
Serve as primary source of energy in the cell
Central to all metabolic processes
Glc-1- phosphate
glycogen
Cytosol - anaerobic

18. Pyruvatecytosol
Acetyl CoA
mitochondria
(aerobic)
Krebs
cycle
Reducing
equivalents
Oxidative
Phosphorylation
(ATP)
AMINO
ACIDS
FATTY ACIDS

19. GLYCOLYSIS

20. Defn: It is defined as sequence of reactions of glucose
to lactate & pyruvate with the production of ATP.
It is derived from greek word glycose -sweet or sugar,
lysis- dissolution.
Site: Cytosolic fraction of cell

21. Glycolysis
 EmbdEn-mEyErhof pathwayEmbdEn-mEyErhof pathway
 (or)(or)
 E.m.pathwayE.m.pathway
Definition:
Glycolysis is defined as the sequence of
reactions converting glucose (or glycogen)
to pyruvate or lactate, with the production
of ATP

22. Reactions of Glycolysis
1) Energy Investment phase (or) priming phase
2) Splitting phase
3) Energy generation phase

24. STAGE III

25. STAGE III

26. STAGE III

27. Bioenergetics in Glycolysis:
Total of 8 ATP is formed in glycolysis.
Oxidation of glucose in aerobic condition:38 ATP
Anaerobic condition: 2 ATP

28. Hemolytic Anaemias: Inherited aldolase A & pyruvate
kinase deficiencies.
Skeletal muscle fatigue
Inherited Pyruvate dehydrogenase deficiency-Lactic
acidosis
Fast growing cancer cells glycolysis proceeds at faster
rate – increased acidic environment-implication in
certain types of cancer.

29. Major storage form of carbohydrate.
Glycogenesis: occurs in muscle & liver.

30. Liver glycogen largely concerned with transport &
storage of hexose units.
For maintenance of blood glucose mainly between
meals.

31. Type of disorder
Type I (Von Gierke’s
disease)
Type II (Pompe’s disease)
Type III (Cori’s disease)
Type IV (Andersen’s
disease)
Type V (Mcardle’s disease)
Cause of disorder
Glucose-6-phosphatase
deficiency.
Acid maltase deficiency.
Debranching enzyme
deficiency.
Branching enzyme
deficiency.
Muscle phosphorylase
deficiency.

32. Type VI (Her’s disease)
Type VII (Tarui’s
disease)
Type VIII
Liver phosphorylase
deficiency.
Phosphofructokinase
deficiency
.
Liver phosphorylase
kinase.

34. 1) Formation of citrate : Condensation of acetyl CoA and
oxaloacetate  catalysed by citrate synthase.
2) & 3) Citrate is isomerized to isocitrate  aconitase
(two steps).
4) & 5) Formation of ᾀ-ketoglutarate : enzyme isocitrate
dehydrogenase.
6) Conversion of ᾀ-ketoglutarate to succinyl CoA :
through oxidative decarboxylation, catalysed by ᾀ-
ketoglutarate dehydrogenase complex.

35. 7)Formation of succinate : enzyme succinate
thiokinase
GTP + ADP  ATP + GDP (nucleoside
diphosphate kinase)
8)Conversion of succinate to fumarase : enzyme
succinate dehydrogenase
9)Formation of malate : enzyme fumarase
10)Conversion of malate to oxaloacetate : enzyme
malate dehydrogenase.

36. CITRIC ACID
CYCLE

37. Final common pathway for oxidation of
carbohydrates, lipids , & proteins.
Major role in gluconeogenesis, transamination,
deamination & lipogenesis.
Vitamins play a key role in this cycle
Eg; Riboflavin – FAD.
Niacin – NAD.
Thiamine.
Pantothenic acid as a part of co-A.
Bioenergetics :12 ATP per cycle.

38. • TCA cycle is strictly aerobic in contrast to glycolysis.
• Total of 12 ATP are produced from one acetyl CoA :-
 During the process of oxidation of acetyl CoA via citric acid
cycle  3 NADH & 1 FADH2.
 Oxidation of 3 NADH by electron transport chain coupled with
oxidative phosphorylation results in 9 ATP, FADH2  2 ATP.
 One substrate level phosphorylation.

39. Alternative route for metabolism of glucose
It occurs in cytosol
Sequence of reactions occur in two phases
1.Oxidative non reversible phase-Forms NADPH
2. Non oxidative reversible phase.- Forms ribose
precursors for nucleotide synthesis.

42. Glutathione peroxidase protects erythrocytes against
hemolysis.
Pentose useful in synthesis of DNA & RNA.
NADPH is required for reductive biosynthesis of fatty
acids & steroids.
NADPH is required in synthesis of amino acids.
Microsomal cytochrome P450 system brings
detoxification of drugs & foreign compounds.

43. Erythrocyte hemolysis
Impairment of generation of NADPH manifests as
hemolysis when given drugs like
Antimalarial- Primaquine aspirin or sulfonamides.
(G6 PD) Deficiency:
 It makes red cells susceptible to hemolysis
 X linked inheritance
 Onset of Anaemia is rapid
 Mild jaundice

44. Defects in Fructose metabolism
Lack of hepatic fructokinase causes Fructosuria.
Absence of Hepatic aldolase-Hereditary fructose
intolerance.
 Hypoglycemia, vomiting, sweating.
 Albuminuria, aminoaciduria.
 Reduced caries incidence.
.
Fructose & sorbitol in lens asssociated with
diabetic cataract.

45.  Starch
 Dextrins
 Inulin
 Glycogen
 Dextrans
 Cellulose
 chitin

46. Starch:carbohydrate reserve of plants .
Presents in cereals ,roots,vegertables ,tubers etc, consists of
repeated units of D-glucose units by alpha glycosidic
bonds
2 polysacaride components –water soluble amylose (15-20%)
Water insoluble amylopectin (80-85%)
Amylose –long unbranched chain (alpha 1-4 linkages)
Amylopectin –branched chain (alpha 1-6 linkages )
Starch -> dextrins->maltose &glucose

47. Agar:present in sea weeds
Not digested
Dietary fiber
Used in microbial culture (agarose)
Pectin :
Present in apples & citrus fruits
Not digested
Used as dietary fibers
Used in preparation of jellies .

48. Seven glycosaminoglycans(GAG)
1 Hyaluronic acid
2 Chondriotin sulfate
3 Keratan sulfate
4 hyaluronidase
5 Heparin
6 Dermatan sulfate

49. Mucopolysaccharides:there also called as
heteropolysacharides or heteroglycans.
Consisting of repeating units of sugars derivatives .
They are amino sugars,uronic acids –knowns as GaG.
Acetylated amino groups are present ,sulfate,,carboxyl
groups are also prsent in GAG structure
Present of sulfate & carbonyl groups ---acidity of molecule
Mucopolysacharide +protein ---------mucoproteins or
mucoids r proteoglycans.
mucopolysacharide ------essential component of tissue
structure.
Present in extracellular spaces of tissues seen in connective
tissue ,cartilage ,bone,skin,tendon,blood vessels .
Present in collagen,& elastic fibers in ground substance
concsits of mainly GAG.

50. Hyaluronic acid :important GAG found in ground substance
of synovial fluid of joints & vitreous human or eyes.
Present as ground substance in conective tissues
Present as gel aroundhe ovum.
Function:lubrication,shock absorber in joints
Structure:alternate units of D-glucorinic acid & n acty D-
Glucosamine units .
It consists 250-25000 disacharide units with beta 1->4
bonds.
Hyalourindase :present in testes ,seminal fluid ,snake &
insect venoms .
Enzyme that’ breaks beta 1->4 bonds of hyaluronic acid.
Hyaluronidase prsent in semen play an important role in
fertlization .by cleaning the hyaluronic acid present around
the ovum & helps inn better penetrations of sperm into
ovum.

51. Heparin;anticoggulant ,present in blood ,liver ,lung
,kidney spleen etc,
Helps in releade of enzyme lipoprotein lipase ->clearing
the turbidity of lipemic plasma
Chondrotin 4 sulphate:prsent in various tissues
9bone,cartilage ,tendons,heart values ,skin,cornea,0in
human beings.
Structure:comparbile same as hyaluronic acid ,consists of
repeating disacharide units of D-GLUCORINIC ACID,& n-
acetyl ,d galactosamine 4 sulphate .

52. MPS
MPS I (Hurler syndrome)
MPS II (Hunter syndrome)
MPS IIIA (Sanfilippo A)
MPS IIIB (Sanfilippo B)
MPS IIIC (Sanfilippo C)
Defect
Alpha-L-Iduronidase
Iduronate sulfatase
Heparan sulfate N sulfatase
Alpha-Acetylglucosaminidase
Acetyl transferase

53. MPS IVA (Morquio A)
MPS IVB (Morquio B)
MPS VI (Maroteaux
Lamy syndrome)
MPS VII (Sly)
Galactose-6-sulfatase
Beta galactosidase
N acetylgalactosamine 4
sulfatase
Beta glucoronidase

54. Hunter’s syndrome

55. Structural components of extracellular matrix.
Act as sieves in extracellular matrix.
Facilitate cell migration.
Corneal transparency.
Anticoagulant (Heparin).
Components of synaptic & other vesicles.

56. Thank you