Biology

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Carbohydrates

  • Polymers 

  • Made of carbon, hydrogen and oxygen 

  • For every one carbon atom, there are two hydrogen and one oxygen 

  • Monomers made up monosaccharides

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Glucose (carb)

  • Monosaccharide with six carbon atoms (hexose monosaccharide) 

  • Two forms of glucose – alpha and beta, both have ring structure 

  • Structure related to function, its soluble and a main energy source, easily transported 

  • Chemical bonds contain a lot of energy

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Ribose (carb)

  • Pentose monosaccharide 

  • Sugar component of RNA nucleotides

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Polysaccharide formation

  • Joined together by 1,6 glycosidic bonds 

  • A hydrogen atom on one binds to a hydroxyl group on the other in a condensation reaction 

  • In hydrolysis, a molecule of water reacts with the glycosidic bond 

  • diasaccharide is formed when two monosaccharides join together

  • polysaccharide is formed when more than two monosaccharides join together
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Functions of Carbs - Starch

  • Main energy storage material in plants 

  • Cells get energy from glucose and plants store excess glucose as starch (when a plant needs more glucose for energy it breaks down starch to release glucose) 

  • Starch is insoluble in water so doesn't cause water to enter cells via osmosis which would make them swell 

  • Good for storage 

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Functions of Carbs - Starch - Amylose and Amylopec

  • Mixture of two polysaccharides of alpha glucose – amylose and amylopectin 

  • Amylose: long, unbranched. Angles of glyco bonds give it a coiled structure. Compact and good for storage. 

  • Amylopectin: long, branched. Side branches allows enzymes that break down the molecule to get the bonds easily for quick release.

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Functions of Carbs - Glycogen

  • Main energy storage material in animals 

  • Store excess glucose as glycogen – another polysaccharide of a glucose. 

  • Similar to amylopectin but more side branches 

  • Stored glucose can therefore be released quicker, important for energy release 

  • Very compact and good for storage

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Functions of Carbs- Cellulose

  • Major component of cell walls in plants. 

  • Long, unbranched chains of beta glucose. 

  • When beta glucose mols bond, they form straight cellulose chains. 

  • Chains linked together by hydrogen bonds to form strong microfibril fibres. 

  • Structural support for cells.

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