Online Counseling Resource YCMOU ELearning Drive… School of Architecture, Science and Technology Yashwantrao Chavan Maharashtra Open University, Nashik – , India

SEP-SBI072-CP1-01 Introduction Programmes and Courses SEP –SBI072- CP1- UN01

School of Science and Technology, Online Counseling Resource… Credits  Academic Inputs by Sonali Alkari Faculty YCMOU Nagpur Centre, Faculty LAD college P.G. D of Biotechnology Research officer Ankur Seeds Pvt Ltd 3© 2008, YCMOU. All Rights Reserved.

School of Science and Technology, Online Counseling Resource… © 2008, YCMOU. All Rights Reserved.4 How to Use This Resource  Counselor at each study center should use this presentation to deliver lecture of minutes during Face-To-Face counseling.  Discussion about students difficulties or tutorial with assignments should follow the lecture for about minutes.  Handouts (with 6 slides on each A4 size page) of this presentation should be provided to each student.  Each student should discuss on the discussion forum all the terms which could not be understood. This will improve his writing skills and enhance knowledge level about topics, which shall be immensely useful for end exam.  Appear several times, for all the Self-Tests, available for this course.  Student can use handouts for last minutes preparation just before end exam.

School of Science and Technology, Online Counseling Resource… © 2008, YCMOU. All Rights Reserved.5 Learning Objectives  After studying this module, you should be able to: Describe carbohydrates, Discuss stereoisomerism Describe enantiomers Discuss empirical formula Describe Fisher and Haworth formula Discuss annomeras

School of Science and Technology, Online Counseling Resource… Carbohydrates-1  Carbohydrates are polyhydroxyaldehydes or ketones,or substances that yield such compounds on hydrolysis.  Many, but not all, carbohydrates have the empirical formula (CH 2 O) n ; some also contain nitrogen,phosphorus, or sulfur. Carbohydrates are the most abundant biomolecules on Earth.  Each year, photosynthesis converts more than 100 billion metric tons of CO 2 and H 2 O into cellulose and other plant products.  Certain carbohydrates(sugar and starch) are a dietary staple in most parts of the world. © 2008, YCMOU. All Rights Reserved.6

School of Science and Technology, Online Counseling Resource… Carbohydrates-2  The oxidation of carbohydrates is the central energy-yielding pathway in most non photosynthetic cells.  Insoluble carbohydrate polymers serve as structural and protective elements in the cell walls of bacteria and plants and in the connective tissues of animals.  Other carbohydrate polymers lubricate skeletal joints and participate in recognition and adhesion between cells.  Carbohydrate make up most of the organic matter on Earth because of their extensive roles in all forms of life. © 2008, YCMOU. All Rights Reserved.7

School of Science and Technology, Online Counseling Resource… © 2008, YCMOU. All Rights Reserved.8 Carbohydrates-3

School of Science and Technology, Online Counseling Resource… Carbohydrates-4  More complex carbohydrate polymers covalently attached to proteins or lipids act as signals that determine the intracellular location or metabolic fate of these hybrid molecules, called glycoconjugates.  Carbohydrates in food are important sources of energy. Starch, found in plant-derived food such as pasta, consists of chains of linked glucose molecules.  These chains are broken down into individual glucose molecules for eventual use ingeneration of ATP and building blocks for other molecules.  Carbohydrates are aldehyde or ketone compounds with multiple hydroxyl groups. © 2008, YCMOU. All Rights Reserved.9

School of Science and Technology, Online Counseling Resource… Carbohydrates-5  Carbohydrates serve as energy stores, fuels, and metabolic intermediates.  Ribose and deoxyribose sugars form part of the structural framework of RNA and DNA.  Polysaccharides are structural elements in the cell walls of bacteria and plants.  In fact,cellulose, the main constituent of plant cell walls, is one of the most abundant organic compounds in the biosphere.  Fourth, carbohydrates are linked to many proteins and lipids, where they play key roles in mediating interactions among cells and interactions between cells and other elements in the cellular environment. 10© 2008, YCMOU. All Rights Reserved.

School of Science and Technology, Online Counseling Resource… Emprical Formula  Carbohydrates are defined as polyhydroxy aldehydes or ketones.  Many carohydrates have the emprical formula (CH 2 O) n where n is 3 or large.  This formula contributed to the belief that carbohyrates could be represented as hydrates of carbons.  But this definition is not suitable when the compounds have general properties of carbohydrates but contained nitrogen or sulphur in addition to carbon,, hydrogen and oxygen. © 2008, YCMOU. All Rights Reserved.11

School of Science and Technology, Online Counseling Resource… Isomerism  The isomerism is divided into structural isomerism and stereoisomerism.  Structural isomers have the same molecular formula but differ from each other by having different structures.  Stereoisomers have the same molecular formula and the same structure but differ in configuration, that is arrangement of atoms in space.  Structural isomeras can be of three types, chain isomers, position isomers annd functional group isomers. © 2008, YCMOU. All Rights Reserved.12

School of Science and Technology, Online Counseling Resource… Stereoisomerism  The stereoisomerism can be divided into optical isomerism and geometric isomerism.  Optical isomerism commonly found in carbohydrates, it is usually encountered when a molecule contains one or more chiral or asymmetric carbon atom.  When four different groups are attached to the carbon atom in the centre of the molecule is said to be chiral centre.  These groups are arranged in space in two different ways so that two different compounds are formed. © 2008, YCMOU. All Rights Reserved.13

School of Science and Technology, Online Counseling Resource… Enantiomeric Pair  The mirror image isomerase constitutes an enantiomeric pair.  one member of the pair is said to be enantiomer of the other.  Pairs of stereoisomers that are not mirror images of each other are called diastereomers. © 2008, YCMOU. All Rights Reserved.14

School of Science and Technology, Online Counseling Resource… Optical Activity  Almost all the properties of the two members of an enantiomeric pair are identical- they have same boiling point, same melting point, the same solubility in various systems.  They exhibit optical activity, in this property they differ in one important manner.  One member of the enatiomeric pair rotate a plan of polarized light in clockwise direction and therefore said to be dextrorotatory.  Its mirror image isomer or enatiomer rotate a plan of polarized light in countervclockwise direction and said to be levorotatory. © 2008, YCMOU. All Rights Reserved.15

School of Science and Technology, Online Counseling Resource… Enantiomers  These molecules have multiple asymmetric carbons, they exist as diastereoisomers, isomers that are not mirror images of each other, as well as enantiomers.  In regard to these monosaccharides, the symbols d and l designate the absolute configuration of the asymmetric carbon farthest from the aldehyde or keto group. © 2008, YCMOU. All Rights Reserved.16

School of Science and Technology, Online Counseling Resource… Projection and Perspective Formula  In the study carbohydrates many examples of optical isomerism encountered and it is necessary to have a means for representing the different possible isomers.  In projection formula the bonds are represented by simple lines, the horizontal bonds are understood to be in front of the plane of paper while vertical bonds are behind.  In perspective formula dashed lines indicates bonds extending behind the plane of the page while solid wedges identigy bonds standing in front of the plane of page. © 2008, YCMOU. All Rights Reserved.17

School of Science and Technology, Online Counseling Resource… Fischer Projection Formula  In a Fischer projection of a molecule, atoms joined to an asymmetric carbon atom by horizontal bonds are in front of the plane of the page, and those joined by vertical bonds are behind  Fischer projections are useful for depicting carbohydrate structures because they provide clear and simple views of the stereochemistry at each carbon center. © 2008, YCMOU. All Rights Reserved.18

School of Science and Technology, Online Counseling Resource… Furanose and Pyranose Rings-1  An aldehyde can react with an alcohol to form a hemiacetal. The resulting cyclic hemiacetal, a six- membered ring, is called pyranose because of its similarity to pyran.  Similarly, a ketone can react with an alcohol to form a hemiketal. The C-2 keto group in the open-chain form of a ketohexose, such as fructose, can form an intramolecular hemiketal by reacting with either the C-6 hydroxyl group to form a six-membered cyclic hemiketal or the C-5 hydroxyl group to form a five- membered cyclic hemiketal  The five-membered ring is called a furanose because of its similarity to furan. © 2008, YCMOU. All Rights Reserved.19

School of Science and Technology, Online Counseling Resource… Furanose and Pyranose Rings-2 © 2008, YCMOU. All Rights Reserved.20

School of Science and Technology, Online Counseling Resource… Haworth Projections-1  W.H. Haworth proposed the first five carbon atoms of the aldohexoses and oxygen atom of the ring better represented as a hexagonal ring in a plane perpendicular to the plane the paper.  When this is done, the substituents on the carbon atom then will extend above or below the plane of the six membered ring.  Carbon atom 6, a substitute on C-5 will therefore be above the plane of the ring. © 2008, YCMOU. All Rights Reserved.21

School of Science and Technology, Online Counseling Resource… Haworth Projections-2  In Haworth projections the carbon atoms in the ring are not explicitly shown.  The approximate plane of the ring is perpendicular to the plane of the paper, with the heavy line on the ring projecting toward the reader.  Like Fischer projections, Hawort projections allow easy depiction of the stereochemistry of sugars. © 2008, YCMOU. All Rights Reserved.22

School of Science and Technology, Online Counseling Resource… Anomers-1  Isomeric forms of monosaccharides that differ only in their configuration about the hemiacetal or hemiketalcarbon atom are called anomers. The hemiacetal (or carbonyl) carbon atom is called the anomeric carbon.  The alpha and ß anomers of D-glucose interconvert in aqueous solution by a process called mutarotation.  Thus, a solution of -D-glucose and a solution of -D-glucose eventually form identical equilibrium mixtures having identical optical properties. © 2008, YCMOU. All Rights Reserved.23

School of Science and Technology, Online Counseling Resource… Anomers-2 © 2008, YCMOU. All Rights Reserved.24

School of Science and Technology, Online Counseling Resource… Epimers  Note that d-glucose and d-mannose differ in configuration only at C- 2.  Sugars differing in configuration at a single asymmetric center are called epimers.  Thus, d glucose and d- mannose are epimeric at C-2; d-glucose and d- galactose are epimeric at C-4. © 2008, YCMOU. All Rights Reserved.25

School of Science and Technology, Online Counseling Resource… What You Learn-1…  You have learnt :  Carbohydrate make up most of the organic matter on Earth because of their extensive roles in all forms of life.  Structural isomers have the same molecular formula but differ from each other by having different structures.  Stereoisomers have the same molecular formula and the same structure but differ in configuration, that is arrangement of atoms in space.  The mirror image isomerase constitutes an enantiomeric pair. 26© 2008, YCMOU. All Rights Reserved.

School of Science and Technology, Online Counseling Resource… What You Learn-2…  You have learnt :  Cyclic hemiacetal, a six-membered ring, is called pyranose because of its similarity to pyran.  A ketone can react with an alcohol to form a hemiketal.  Isomeric forms of monosaccharides that differ only in their configuration about the hemiacetal or hemiketalcarbon atom are called anomers.  Sugars differing in configuration at a single asymmetric center are called epimers. 27© 2008, YCMOU. All Rights Reserved.

School of Science and Technology, Online Counseling Resource… Critical Thinking Questions 1.What is isomerism? Describe its different types explain with example? 2. Why carbohydrates important ? 3.What are epimerse and annomers? 4.Describe projection and perspective formula in details? © 2008, YCMOU. All Rights Reserved.28

School of Science and Technology, Online Counseling Resource… Hints For Critical Thinking Question 1.Similarity and structural isomerism and stereoisomerism. 2.Organic matter on Earth. 3.Difference in configuration at a single asymmetric center and difference in configuration about the hemiacetal or hemiketalcarbon atom 4.a means for representing the different possible isomers, open chain and cyclic structures © 2008, YCMOU. All Rights Reserved.29

School of Science and Technology, Online Counseling Resource… Study Tips:1  Book1 Title: Molecular Cell Biology Author: Harvey Lodish, David Baltimore Publisher: W. H. Freeman and Company  Book2 Title: Principles of Biochemistry Author: AlbertL Lehninger Publisher:CBS Publishers & Distributors

School of Science and Technology, Online Counseling Resource… Study Tips:2  Book3 Title: Biochemistry Author: Lubert stryer Publishers: Freeman International  Book4 Title: Biochemistry Author: Keshav Trehan Publishers: Wiley Eastern

School of Science and Technology, Online Counseling Resource… Study Tips Microsoft Encarta Encyclopedia Wikipedia the free encyclopedia

School of Science and Technology, Online Counseling Resource… End of the Presentation Thank You ! 33© 2008, YCMOU. All Rights Reserved.