2 examples = Maltose and Sucrose
Maltose = 2 glucose molecules produced when amylase breaks down starch
Sucrose = Form in which sugar is transported around the plant
The monomers which make up disaccharides =
- Glucose joined to glucose forms maltose
- glucose joined to fructose forms surcose
- glucose joined to galactose forms lactose
Disaccarides need to be digested before they can produce energy sugars are often stored in this form.
Oil rig = oxidation is lost reduction is gain (of electrons)
The Benedicts test= shows the relationship between the concentration of reducing sugars.
The differences in colour mean that the benedicts test is semi-quantitative.
colours for the benedicts test=
green =none, yellowish green = very low, yellowish brown= low, dark brown = medium, red= high
Benedicts reagent turns red when heated with a reducing sugar beacuse the sugar gains more electrons making the bonds stronger.
another way of testing this is the starch test
Gulcose = Main sugar used for respiration starch and glycogen are polymers of glucose is absorbed and transported in the blood in the blood stream to cells
Galactose = mainly in our diet as part of lactose of lactose disaccharide
fructose = sugar found naturally in fruit, honey and some vegetables
Carbohydrates - polysaccharides
carbohydrates and polysaccharides
monosaccharides = glucose, glactose,fuctose
Disaccharides = maltose, lactose, sucrose
polysaccharides = starch, glycogen, cellulose
ploysaccharides are polymers containing many monosaccharides linked y glycosiolic bonds. like disaccharides polysaccharides are formed by condensation reactions
the major polysaccharides are starch and cellulose in plants and glycogen in animal.
As polysaccharides are very large they are insoluble =used for storage
Test for starch
starch is easily detectable by its ability to change colour of the iodine in a potassium iodine solution from yellow to blue- black the test is carried out at room temperature
Place 2cm cubed of the sample being tested into a test tube (or 2 drops on a spotting tray)
Add 2 drops of iodine solution and shake or stir
The presence of starch is indicated by a blue- black coloration