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Glycosidic bond |
Peptide bond |
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(1) Join monosaccharide units. (2) Forms by the reaction between aldehyde or ketone group and alcohol groups. (3) Links two carbon atoms through an oxygen atom.
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(1) Join amino acid units. (2) Forms by reaction between amino acids and carboxyl groups. (3) Links carbon and nitrogen atoms. |
pleated sheet structure of a protein.
pleated sheet is a type of secondary structure It consists of polypeptide chains arranged in an anti-parallel or parallel fashion. They are joined by hydrogen bounds between CO and NH groups of adjacent chains. Examples. Silk fibrolin.β-pleated sheets of polypeptides
1. Reserve food-materials. Some of the polysaccharides reserve food in animal and plant cells. The reserve food material in animals is glycogen whereas starch is of the plants.
2. Fuel. They are used as fuel. These polysaccharides are converted into monosaccharides and are oxidized for the release of energy.
3. Structural component. Some of the polysaccharides are structural component of the cells. For example some polysaccharides are involved in the formation of biomembranes. Cellulose and chitin are the main structural components.
4. Protective coat. Cell membrane made up of polysaccharides protects the cell.
(2) They have sweet taste and char on heating.
(3) Most of them are reducing in nature.
(1) They give shape to the cell.
(2) They provide protection.
(3) They prevent bursting of cells in water.
(4) They form fibres for mechanical support.
(5) They are a major contituent of the cell wall.
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