Monosaccharides are joined together by Glycosidic Bonds
Examples of monosaccharides are Alpha glucose and Beta glucose
Test for reducing Sugars
- 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.
"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
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