BY1-biological molecules-carbohydrates
- Created by: Izzy
- Created on: 11-02-14 08:52
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- Carbohydrates
- Mono-saccharides
- Building blocks for larger proteins. eg. glucose used to make starch, glycogen, cellulose.
- (CH2O)n. Name determined by number of carbon atoms. Triose, hexose.
- Ring structure when dissolved in water.
- Source of energy in respiration. C-H bonds broken (releases energy.) Transferred to make ATP from ADP.
- Disaccharides
- Two monomers linked together. Glycosidic bond- elimination of water (condensation reactio)
- Glucose + fructose= sucrose Glucose + galactose= lactose
- Used for transport and storage.
- Testing for presence of sugars
- Benedict's reagent used to test for presence of glucose
- Equal volume reagent added to solution. Heat in boiling water bath.
- Reducing sugar present: green-yellow-orange-brick red.
- Some disaccharides are non reducing sugars eg. sucrose
- Sucrose can only be detected if broken down by heating with HCL. Needs neutralising. Add Benedicts asn before.
- Polysaccharides
- Starch
- alpha glucose. Amylose- linear, coils into helix. Amylopectin- branched, fits inside amylose.
- Glucose storage. Glucose dissolves and would increase concentration. Water drawn in by osmosis.
- Compact molecule
- 1,4 linkages cause the chain to turn and coil
- Glycogen (animal storage) Similar to amylopectin but more brached.
- Readily hydrolysed to alpha glucose (soluble and transportable)
- Test: Add iodine solution. Blue black.
- Cellulose
- Structural polysaccharide. In plant cell walls
- Long parallel chains of beta glucose. H bond= structural stability.
- Adjacent b glucose molecules rotated 180. H bonds between hydroxyl groups of adjacent chains.
- 60-70 cellulose molecules become tightly cross linked to form bundles called microfibrils. These are held together in bundles (fibres)
- Freely permeable
- Chtitin
- Found in insects.
- Similar to cellulose but has amino acids added to form a mucopolysaccharide
- Strong, waterproof, lightweight. Forms exoskeleton of insects.
- Starch
- Mono-saccharides
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