Carbohydrates
- Created by: kim.a.r
- Created on: 24-03-14 15:00
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- Carbohydrates
- Monosaccharides
- Have a general formula CH2O
- Glucose exists as two isomers
- Alpha Glucose
- Beta Glucose
- Function: a source of energy in respiration. C-H bonds broken to release energy
- Function: act as building blocks for larger molecules
- Disaccharides
- 2 monosaccharide units linked together with the formation of glycosidic bonds and the elimination of water
- The elimination of water is also referred to as the condensation reaction
- Glucose + Glucose = Fructose
- Glucose + Fructose = Sucrose
- Glucose + Galactose = Lactose
- Function: For storage and transport
- 2 monosaccharide units linked together with the formation of glycosidic bonds and the elimination of water
- Polysaccharides
- Starch
- The main source of energy in cells. Starch is insoluble which prevents water being drawn into a cell
- Starch is found in plant cells in the form of starch grains.
- Starch is made up of alpha glucose and consists of two polymers, amylose and amylopectin. Amylose is linear whereas amylopectin is branched
- The 1-4 linkages causes the chain to turn and coil. the main storage product in animals is called glycogen
- Both starch and glycogen are readily hydrolysed to alpha glucose which is soluble and can be transported to areas in need of energy
- Cellulose
- A structural polysaccharide, it is present in the cell walls of plant cells
- Long parallel chains of beta glucose cross-linked to each other by hydrogen bonds
- The chain has adjacent glucose molecules rotated by 180 degrees
- The hydrogen bonds form between the hydroxyl groups of the adjacent parallel chains
- Gives cellulose its structural stability
- 60 to 70 cellulose molecules can become tightly cross-linked forming microfibrils
- Chitin
- A polysaccharide found in insects
- Similar to cellulose but has amino acids added to it
- It is strong, waterproof and light weight
- Forms the exoskeleton of insects
- Starch
- Monosaccharides
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