Organic and biochemistry Assistance Lecturer Amjad Ahmed Jumaa  Carbohydrates; mono saccharides.  Osazone formation.  Disaccharides; poly saccharides.  amino acids and proteins  Properties of amino acids. 1

Carbohydrates: The Latin word for sugar is (saccharum). (+)-Glucose, cellulose, starch, and glycogen all belong to the class of organic compounds known as carbohydrates. Carbohydrates are polyhydroxy aldehydes, polyhydroxy ketones. A carbohydrate that cannot be hydrolyzed to simpler compounds is called a monosaccharide. A carbohydrate that can be hydrolyzed to two monosaccharide molecules is called disaccharide. And this in which can be hydrolyzed to many monosaccharide molecules is called a polysaccharide. Monosaccharide: Monosaccharide is also classified into:

1-aldose, if it contain aldehyde group. 2-ketose, if it contains a keto group. A monosaccharide is known as a triose, tetrose, pentose, and hexose. For example:

A) An aldohexose: is a six-carbon monosaccharide containing an aldehyde group. For example, (+)-Glucose, has the molecular formula (C 6 H 12 O 6 ). A six-carbon, straight-chain, pentahydroxy aldehyde that is (+)-glucose is an aldohexose.

B) A ketopentose: is a five-carbon monosaccharide containing a keto group. For example, L-Xylulose has the molecular formula (C 5 H 10 O 5 ). A five-carbon, straight-chain, butahydroxy keto, and thus L-Xylulose is a ketopentose.

Osazone formation: As aldehydes, aldoses react with phenyl hydrazine to form phenyl hydrazones. By uses excesses of phenyl hydrazine the products known as osazones. Osazones contain two phenyl hydrazine residues per molecule. Disaccharides: Disaccharides are carbohydrate that are made up of two monosaccharide units, on hydrolysis a molecule of disaccharides yields two molecules of monosaccharide.

1-(+)-Maltose: 1-Can be obtained by partial hydrolysis of starch in aqueous acid. 2-has molecular formula (C 12 H 22 O 11 ). 3-it reduces Tollens' and Fehling's reagents and hence is a reducing sugar. 4-It reacts with phenyl hydrazine to yield an osazone (C 12 H 20 O 9; = NNHC 6 H 5 ) 2. 5-It is oxidized by bromine water to a monocarboxylic acid, (C 11 H 21 O 10 ) COOH, maltobionic acid.

2-(+)-Sucrose: 1-Is our common table sugar, obtained from sugar cane and sugar beets. 2-It has the molecular formula (C 12 H 22 O 11 ). 3-it does not reduce Tollens' or Fehling's reagent. It is a non reducing sugar, and in this respect it differs from other disaccharides. 4-(+)-Sucrose dose not form an osazone.

Polysaccharides: 1-made up of many-hundreds or even thousands-monosaccharide units per molecule. 2-Polysaccharides are naturally occurring polymers, which can be considered as derived from aldoses or ketoses by condition polymerization. 3-A polysaccharides derived from hexoses, for example, has the general formula (C 6 H 10 O 5 ) n. 4- In general starch contains 20% of a water-soluble fraction called amylose, and 80% of a water-insoluble fraction called amylopection.

Amino acid and proteins: 1-proteins are taken from the Greek"proteios", which means first. 2-They are the substance of life. 3-They make up a large part of the animal body, they hold it together, and they are run it. 4-They are found in all living cell, they are principle material of skin, muscle, tendons, nerves, and blood; of enzymes, antibodies, and many hormones. 5-Chemically proteins are high polymers. amino acids they are carboxylic acids that contain an amine function.

An amide bond between the carboxylic acid function of one amino acid and the amino nitrogen of another is called a peptide bond. Look at the following. A dipeptide is a molecule consisting of two amino acids joined by a peptide bond.

Properties of the amino acids: Some amino acids in addition to the carboxyl group and the amino group alpha to it, they contain a second carboxyl group, example, (aspartic acid or glutamic acid.).And other may contain a second basic group, example, (lysine). Also we see amino acids as dipolar ions, let us take some physical and chemical properties: 1) The amino acids are non-volatile crystalline solids. 2) They are insoluble in non-polar solvent like petroleum ether. 3) Their aqueous solutions behave like solutions of substance of high dipole moment.

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