Elements in biological molecules
Elements Carbohydrates C H O Simple sugars Longer = Starch Proteins C H O N Amino Acids Proteins Lipid C H O Fats = animals, oils = plants
Sugars Starch Glycogen
Amino acids Protein
Glycerol Fatyacids lipid
Test for Starch and Glucose
Test for Starch
Dilute iodine solution reacts with starch, forming a very dark blue colour. This test will work on a solid sample of food, such as potato, or a suspension of starch on water.
Test for Glucose
Glucose is called a reducing sugar. This is because the test for glucose involves chemically reducing an alkaline solution of copper sulphate to copper(I) oxide.
The test for glucose is called the Benedict’s test. Simply add a few drops of Benedict’s solution, which contains alkaline copper sulphate, to some glucose. Add enough to turn the mixture blue. Then heat the mixture in a boiling water bath. The clear blue solution will gradually change colour, forming a cloudy orange or brick red precipitate of copper(I) oxide. All ‘single’ sugars such as fructose are reducing sugars, as well as some ‘double’ sugars, such as the milk sugar
Enzymes are biological catalyst which increases the rate of reation without being udes up in the reation. Enzymes that are folded into compex chapes that allow smaller substnces to fit into the active site. The place where the substrate fits in is called the active site.
Lock and Key Theory
The lock and key theory compares the substrate to a key and the active site to a lock. Only one specific key can open one specific lock. If that lock was denatured – it would change shape. Now if the lock changed shape, it wouldn’t be able to fit into the key anymore.
Temperature and enzymes
As the temperature increases, so does the rate of reaction. But very high temperatures denature enzymes.
Enzymes in Digestion
The enzymes involved in respiration, photosynthesis and protein synthesis work inside cells.