Carbohydrates

Monosaccharides are joined together by Glycosidic Bonds

Examples of monosaccharides are Alpha glucose and Beta glucose

• Add 2 Cm^3 of the food sample to a test tube (if not liquid already; grind up in water)
• Add an equal volume of Benedict's Reagent
• Heat the mixture in an 80^C water bath

If a red precipitate forms then a reducing sugar is present

If the mixture stays blue then a reducing sugar is not present

Disaccharides are two monsaccharides joined together during a condensation reaction to form a glycosidic bond.

It is called a condensation reaction because a molecule of water is removed during the reaction

When water is added to the disaccharide, it breaks the glycosidic bond and releases its constituent monosaccharides- this is called hydrolysis

To remember the difference between condenstation and hydrolysis.

"Hydro"- water

"lysis "- Breaking/ bursting 

water breaking- hydrolysis

Made of Alpha glucose- when hydolysed it release alpha glucose which is transported and released easily for respiration

Insoluble- so water is not drawn in by Osmosis

Large Molecule- so it does not diffuse out of the cell

1,4 glycosidic Bonds

Compact molecules- so can be stored in a small place

Amylose - Coils

Amylopectin- Branches

Made of Alpha Glucose

Insoluble in Water- does not draw water into the cells by Osmosis

Compact molecule- Lots of it can be stored in a small place

Highly branched- more ends to be acted on by enzymes. More readily broken down into monomers which are used in respiration. 

Made of Beta Glucose

Flips to make glycosidic bonds

Insoluble- does not draw water into the cell by Osmosis

Straight, unbranched chains- Allows hydrogen bonds to make cross linkages between adjacent chains.

The flipping makes it stronger and so used in cell walls