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Carbohydrates (part 2) - Coggle Diagram
Carbohydrates (part 2)
Polysaccharides
A polysaccharide is formed when more than two monosaccharides are joined together by condensation reactions.
The three main polysaccharides are: starch, glycogen and cellulose.
Starch
Energy storage in plants
Cells get energy from glucose. Plants store excess glucose as starch and breaks it down when the plant needs glucose for energy.
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Amylose - long, unbranched chain. Coiled structure form glycosidic bonds. Compact and good for storage.
Amylopectin - long, branched chain of α-glucose. Side branches allow enzymes to break down the glycosidic bonds easily so glucose can be released.
It is insoluble and doesn't affect water potential (doesn't cause water to enter cells by osmosis). This makes it good for storage.
Iodine test
Just add iodine dissolved in potassium iodide solution to the test sample. If there is starch present the sample will change form brown/orange to blue/black.
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Cellulose
β-glucose molecules bond, they form straight cellulose chains.
Chains linked together by hydrogen bonds to form strong fibres called microfibrils. These strong fibres provide structural support for the cell wall in plants.
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