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Carbohydrates (Monosaccharides (Functions (Energy in respiration, Building…
Carbohydrates
Monosaccharides
Small organic molecules with general formula (CH20)n and names determined by number of carbon atoms in the molecule.
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The carbon atoms of monosaccharaides make a ring when the sugar is dissolved in water, an they can alter their binding to make straight chains, with the rings and chains in equilibrium.
Glucose has 2 isomers (a and b-glucose) based on the positions of O and OH. These different forms result in biological differences when they form polymers, such as starch and cellulose.
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Polysaccharides
Large complex polymers formed from large number of monosaccharide units, which are their monomers, linked by glycosidic bonds.
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Starch
Starch is insoluble so has no osmotic effect, cant diffuse out of cell, is a compact molecule and can be stored In a small space and carries lots of energy in its bonds.
a-glucose molecules bonded in 2 ways, forming polymers; amylose and amylopectin.
Amylose is linear an unbranched with a a-glycosidic bond forming between first carbon atom on 1 glucose monomer and 4th carbon.
Amylopectin also has chains. Cross linked with a-1,6 glycosidic bonds and fit inside the amylose. Side branch is seen when bond forms between C1 and C6 atom.
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Cellulose
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Consists of long parallel chains of B-glucose units. The bonds allow hydrogen bonds to form between OH groups of adjacent parallel chains and contributes to its structural stability.
60/70 cellulose molecules become tightly cross-linked to form bundles called microfibrills, held in fibres.
Cellulose fibres are freely permeable because there are space between the fibres. Water and its solutes can penetrate through the spaces in the cell wall, to the cell membrane.
Glycogen
storage product in animals. has a a-1,4 and a-1,6 bonds. Branched as shorter 1,4 linked chains.
Chitin
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Long chains of B-1,4 linked monomers, but has groups derive from amino acids added, to form a heteropolysaccharide.
Strong, waterproof and lightweight.
Long chains cross-linked to each other by hydrogen bonds, forming microfibrills.
Disaccharides
Composed of 2 monosaccharide units bonded together with the formation of a glycosidic bond and elimination of water (condensation reaction).
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Some are non reducing sugars (sucrose) and give negative result in testing for presence of sugars. Solution remains blue when equal volumes of benedict reagent and solution are heated to 70 degrees.
Organic compounds containing Carbon Hydrogen and Oxygen. 2 monosaccharaides make a disaccharide and many monosaccharaides combine to form a polysaccharide.