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Chapter 18 and GHW#8 Questions Carbohydrates Carbohydrates Organic compounds containing many -OH groups (polyhydroxy), and aldehydes or ketones functional groups. They are called sugars. Aldoses: Aldehyde sugars are called aldoses. Ketoses: Ketone sugars are called ketoses. Formula for Cabohydrates: CnH2nOn or Cn(H2O)n (hydrates of C) n= number of atoms Monosaccharides They consist of one sugar containing 3,4,5,6 and 7 carbon atoms Disaccharides Polysaccharides Drawing Sugar Molecules Linear structure-Fischer projection CHO Aldehyde H HO OH H CH2 OH O HO Ketone H H OH H OH H OH H OH CH2 OH Glucose Polyhydroxy aldehyde CH2 OH Fructose Polyhydroxy ketone Types of sugars Number fo carbon atoms • Triose sugar units containing three carbon atoms • Tetroses sugar units containing four carbon tomsa • Pentoses sugar units containing five carbon atoms • Hexoses sugar units containing six carbon atoms Chirality: Handedness in Molecules Most monosaccharaides exist in two forms: a “left handed” and “right handed” form due to chiral carbon atoms CHO CHO HO H H OH C C CH2OH CH2OH CHO CHO HO H CH2OH H OH CH2OH Chirality and Optical Activity D L L isomers D isomers Polarimeter assigns D and L isomers D-rotated to right L-rotates to left Cyclic anomeric forms: a- and b- forms Fischer structure Haworth structures ALDEHYDE sugar or aldoses + alcohol --- hemiacetal (cyclic ring) 1) Give names of the following carbohydrates. Identify the chiral carbon atoms with * 2) Circle the correct classifications that apply to the following carbohydrates. 2) Circle the correct classifications that apply to the following carbohydrates. 2) Complete the names, circle carbon atom numbers of the OH group which is on the left and the structure for following aldohexoses. 2) Complete the names, circle carbon atom numbers of the OH group which is on the left and the structure for following aldohexoses. 2) Complete the names, circle carbon atom numbers of the OH group which is on the left and the structure for following aldohexoses. 2) Complete the names, circle carbon atom numbers of the OH group which is on the left and the structure for following aldohexoses. How you get cyclic hemiacetal form of the ketohexose sugar Dfructofuranose with b-anomeric. How you get cyclic hemiacetal form of the ketohexose sugar D-glucopyranose with banomeric. 4) a) Complete the following diagram to get the cyclic hemiacetal form of the aldohexose sugar Dglucopyranose with b-anomeric configuration. 4) b) Draw the structure of b-D-mannopyranose 4) c) What is the difference between pynanose and furanose types of sugars? d) What is the difference between a and b forms of cyclic hemiacetal forms of sugars? 5) Convert the hemiacetal cyclic structures (Haworth Projections) for following carbohydrates to Fischer Projections. a) Use the procedure we used in problem 4 to get linear form of the hexoketose sugar from cyclic D-fructofuranose with b-anomeric 5) b) Use the procedure we used in problem 4 to get linear form of the hexoaldose sugar from cyclic D-sugarpyranose with a-anomeric Glycosidic bonds • Glycosidic bond- covalent bond between a hemiacetal or hemiketal and an alcohol. 6) What are the following? What is/are glucosidic linkage found in them? a) Starch: b) Amylopectin: c) Glycogen: d) Cellulose 7) Answer following question about glycosidic bond of the di-, oligo- and polysaccharides. a) Name of the following glucoside 8) b) Name of the following N-Glycoside c) Name of the following glucoside. 8) d) The following is a part of a cellulose polymeric chain. What is the type of glucosidic linkage? Nucleic Acids phosphate-group+pentose-sugar+Base D-Ribos D-deoxyribose • Deoxysugar or D-deoxyribose: ribose-derivative with an oxygen missing on C-2. Nucleic Acids Bases Purines pyrimidines 8) e) What is DNA? Describe the components. 8) f) What is RNA? Describe the components.