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Carbohydrates Structure and functions- Biochemistry PPT for Students & Educators
Welcome to this comprehensive SlideShare presentation on carbohydrates, one of the most fundamental and essential topics in biochemistry. Whether you’re a medical student, biology enthusiast, nursing student, or allied health science learner, this PowerPoint offers a complete breakdown of carbohydrate chemistry, types, structures, metabolic roles, and biological significance. This educational content is highly suitable for academic presentations, exam preparation, and quick conceptual revisions. 📘 What Are Carbohydrates? Carbohydrates are organic compounds composed of carbon (C), hydrogen (H), and oxygen (O), usually with the general formula Cn(H2O)n. They are also known as saccharides, a term derived from the Greek word for sugar. Carbohydrates play critical roles in providing energy, structural support, and cell signaling in all forms of life. In biochemistry, carbohydrates are considered macronutrients and serve as the body's primary energy source, particularly glucose. In plants, they serve as energy storage (starch) and structural material (cellulose). 🧬 Classification of Carbohydrates (Types) Carbohydrates are broadly classified into four main types: 1. Monosaccharides (Simple Sugars) These are the basic units of carbohydrates that cannot be hydrolyzed into simpler sugars. They include: Glucose Fructose Galactose Ribose Monosaccharides are characterized by the presence of an aldose or ketose group and vary in the number of carbon atoms (triose, tetrose, pentose, hexose). 2. Disaccharides Disaccharides are formed when two monosaccharides are linked by a glycosidic bond. Examples include: Sucrose = Glucose + Fructose Lactose = Glucose + Galactose Maltose = Glucose + Glucose Disaccharides are water-soluble, sweet, and commonly found in our diet. 3. Oligosaccharides These are chains containing 3 to 10 monosaccharide units. They are involved in cell recognition and immune response, often found on cell surfaces. 4. Polysaccharides (Complex Carbohydrates) These are long chains of monosaccharide units. Based on function and composition, polysaccharides are divided into: Storage polysaccharides (e.g., starch in plants, glycogen in animals) Structural polysaccharides (e.g., cellulose in plant cell walls, chitin in fungi and arthropods) Polysaccharides are generally insoluble in water, non-sweet, and serve critical structural and energy storage roles. ⚛️ Structure of Carbohydrates Carbohydrates exhibit different structures based on the number of sugar units and the type of glycosidic linkages. Key structural elements include: Linear and branched chains α (alpha) and β (beta) glycosidic bonds Pyranose (6-membered) and furanose (5-membered) ring structures Isomerism (stereoisomers, enantiomers, epimers)
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Carbohydrates Structure and functions- Biochemistry PPT for Students & Educators
- 1. 08/06/2025 1 Carbohydrates Sajid Afridi BSAnesthesia Khyber Medical University
- 2. 08/06/2025 2 Carbohydrates • Carbohydrates-Carbon hydrates ( C- H20) • Polyhydroxy aldehyde or ketones. • Many, but not all, carbohydrates have the empirical formula (C- H20)n • Most abundant biomolecules on the earth • Three major classes of carbohydrates: • Monosaccharides, oligosaccharides, and polysaccharides • (The word “saccharide” is derived from the Greek sakcharon, meaning “sugar”).
- 3. 08/06/2025 3 Monosaccharides • Monosaccharidesare the simplest carbohydrates. • They are colorless, crystalline solids that are freely soluble in water but insoluble in nonpolar solvents. • The simplest monosaccharides are the two three-carbon trioses: glyceraldehyde and dihydroxyacetone.
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- 5. 08/06/2025 5 Monosaccharides • Monosaccharideswith four, five, six, and seven carbon atoms in their backbones are called, respectively, tetroses, pentoses, hexoses, and heptoses. • The D-glucose and D-fructose are the most common monosaccharides in nature. • The aldopentoses, D-ribose and 2-deoxy-D-ribose are components of nucleotides and nucleic acids.
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- 7. 08/06/2025 7 Asymmetric orChiral Centers • Carbon to which four different atoms or groups are attached is called asymmetric. • All the monosaccharides except dihydroxyacetone contain one or more asymmetric (chiral) carbon atoms and thus occur in optically active isomeric forms- Enantiomers or Mirror images. • To represent three-dimensional sugar structures on paper, we often use Fischer projection formulas.
- 8. 08/06/2025 8 Epimers • Twosugars that differ only in the configuration around one carbon atom are called epimers. • D-glucose and D-mannose, which differ only at C-2 and D-glucose and D- galactose (which differ at C-4) .
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- 10. 08/06/2025 10 Tautomerism • Tautomersare constitutional isomers of a compound which differ only in the position of the protons and electrons. • The carbon skeleton of the compound is unchanged. • A reaction which involves simple proton transfer in an intramolecular fashion is called a tautomerism. • Keto-enol tautomerism is a very common process, and is acid or base catalyzed
- 11. 08/06/2025 11 Hemiacetals andhemiketals • They are formed when an alcohol oxygen atom adds to the carbonyl carbon of an aldehyde or a ketone.
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- 13. Cyclization of glucoseto its hemiacetal form 08/06/2025 13
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- 15. 08/06/2025 15 Anomers andring structure • Isomeric forms of monosaccharides that differ only in their configuration about the hemiacetal or hemiketal carbon atom are called anomers, and the carbonyl carbon atom is called the anomeric carbon. • Pyranose is a six-membered ring with Oxygen bridge between C no.1 and 5. • Furanose is a five-membered ring with oxygen bridge between C no.1 and 4. • The systematic names for the two ring forms of D-glucose are therefore alpha-D-glucopyranose and beta-D-glucopyranose.
- 16. 08/06/2025 16 Pyranose andFuranose ring structure Pyranoses and furanoses. The pyranose forms of D-glucose and the furanose forms of D-fructose are shown here as Haworth perspective formulas. The edges of the ring nearest the reader are represented by bold lines. Pyran and furan are shown for comparison.
- 17. 08/06/2025 17 Glycosides • Whenthe hydroxyl group of one monosaccharide reacts with the hydroxyl group of another monosaccharide, it forms glycosidic linkage. • Glycosides are compounds in which a monosaccharide is attached at the anomeric carbon to an alcohol residue of non-carbohydrate. • The non-carbohydrate residue is called aglycon.
- 18. 08/06/2025 18 Physiologically importantglycosides 1. Glucovanillin (vanillin-D-glucoside) is a natural substance that imparts vanilla flavor. 2. Cardiac glycosides (steroidal glycosides): Digoxin and digitoxin contain the aglycone steroid and they stimulate muscle contraction. 3. Streptomycin, an antibiotic used in the treatment of tuberculosis is a glycoside. 4. Ouabain inhibits Na+ –K+ ATPase and blocks the active transport of Na+.
- 19. 08/06/2025 19 Reducing Sugars •All sugars having a free aldehyde group in open chain form (solution) • Monosaccharides can be oxidized by relatively mild oxidizing agents such as cupric (Cu2) ion. The carbonyl carbon is oxidized to a carboxyl group. • All Monosaccharides such as Glucose, fructose, glyceraldehyde, galactose etc. and disaccharides lactose and maltose can reduce cupric ion and are called reducing sugars. • Cupric ion oxidizes glucose and certain other sugars to a complex mixture of carboxylic acids. This is the basis of Fehling’s reaction.
- 20. 08/06/2025 20 Ring structure-Haworth formula • Cyclic structures of sugars are more accurately represented in Haworth perspective formulas than in the Fischer projection commonly used for linear sugar structures. • In Haworth projections the six-membered ring is tilted to make its plane almost perpendicular to that of the paper, with the bonds closest to the reader drawn thicker than those farther away and numbering of the carbons is done in a clockwise direction beginning with the anomeric carbon.
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- 22. 08/06/2025 22 Disaccharides • Disaccharides(such as maltose, lactose, and sucrose) consist of two monosaccharides joined covalently by an O-glycosidic bond, which is formed when a hydroxyl group of one sugar molecule, typically cyclic, reacts with the anomeric carbon of the other . • Because maltose has a free OH group at C-1 of glucose, it is a reducing sugar.
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- 25. 08/06/2025 25 Sucrose nota reducing substance
- 26. 08/06/2025 26 Polysaccharides • Mostcarbohydrates found in nature occur as polysaccharides • Polysaccharides, also called glycans, differ from each other in the identity of their recurring monosaccharide units, in the length of their chains, in the types of bonds linking the units, and in the degree of branching. • Homopolysaccharides contain only a single monomeric species • Heteropolysaccharides contain two or more different kinds
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- 29. 08/06/2025 29 Glycogen branches every 8-12glucose units Amylopectin branches about every 24-30 linear linkages
- 30. 08/06/2025 30 Heteropolysaccharides • Theseheteropolysaccharides, the glycosaminoglycans, are a family of linear polymers composed of repeating disaccharide units. They are unique to animals and bacteria and are not found in plants. • Hyaluronic acid forms clear, highly viscous solutions that serve as lubricants in the synovial fluid of joints and give the vitreous humor of the vertebrate eye its jellylike consistency (the Greek hyalos means “glass”.
- 31. 08/06/2025 31 Heteropolysaccharides • Hyaluronanis also a component of the extracellular matrix of cartilage and tendons, to which it contributes tensile strength and elasticity. • Hyaluronidase, an enzyme secreted by some pathogenic bacteria, can hydrolyze the glycosidic linkages of hyaluronan, rendering tissues more susceptible to bacterial invasion.
- 32. 08/06/2025 32 Chondroitin Sulfate •Chondroitin sulfate (Greek chondros, “cartilage”) contributes to the tensile strength of cartilage, tendons, ligaments, and the walls of the aorta. • Dermatan sulfate (Greek derma, “skin”) contributes to the pliability of skin and is also present in blood vessels and heart valves.
- 33. 08/06/2025 33 Agar • Agaris a complex mixture of polysaccharides. • The remarkable gel-forming property of agarose makes it useful in the biochemistry laboratory. • Agarose gels are used as inert supports for the electrophoretic separation of nucleic acids, an essential part of the DNA-sequencing process. • Agar is also used to form a surface for the growth of bacterial colonies. • Another commercial use of agar is for the capsules in which some vitamins and drugs are packaged.
- 34. 08/06/2025 34 Biomedical Importanceof Carbohydrates • Chief source of energy. • Constituents of compound lipids and conjugated proteins. • Certain carbohydrate derivatives are used as drugs like cardiac glycosides/antibiotics. • Lactose principal sugar of milk—in lactating mammary gland. • Degradation products utilized for synthesis of other substances such as fatty acids, cholesterol, amino acid, etc.
- 35. 08/06/2025 35 Biomedical Importanceof Carbohydrates • Constituents of mucopolysaccharides which form the ground substance of mesenchymal tissues. • Inherited deficiency of certain enzymes in metabolic pathways of different carbohydrates can cause diseases, e.g. galactosemia, glycogen storage diseases (GSDs), lactose intolerance, etc. • Derangement of glucose metabolism is seen in diabetes mellitus. • Seminal fluid is rich in fructose and sperms utilise fructose for energy. Fructose is formed in the seminiferous tubular epithelial cells from glucose.
- 36. 08/06/2025 36 Biomedical Importanceof Carbohydrates • Various food preparations, such as baby food are produced by hydrolysis of grains and contain large amounts of maltose. • From nutritional point of view they are thus easily digestible. • In lactating mammary gland, the lactose is synthesised from glucose by the duct epithelium and lactose present in breast milk is a good source of energy for the newborn baby.
- 37. 08/06/2025 37 Biomedical Importanceof Carbohydrates • Glycosides are found in many drugs, spices and in the constituents of animal tissues. • Cardiac glycosides- digitalis • Agar • In human: Used as laxative in constipation. Like cellulose, it is not digested, hence add bulk to the faces (“roughage” value) and helps in its propulsion. • In microbiology: Agar is available in purified form. It dissolves in hot water and on cooling it sets like gel. It is used in agar plate for culture of bacteria.