BIOLOGY
Biology Revision Notes
Biochemical Tests:
Proteins - add biurettes reagent to the sample. If protein is present, clear colour change from blue to purple.
Reducing Sugars – add Benedict’s reagent to the sample. Heat in Bunsen or water bath. If reducing sugars are present, clear colour changes from blue -> orange red precipitate.
Lipids – dissolve sample in ethanol. Slowly pour the solution into the water slowly. If lipids are present a white emulation forms on the surface.
Starch – add iodine solution to the sample. If starch is present clear colour change from orange red to blue black.
Non reducing sugars – do the reducing sugars test. Add Benedict's to the sample & heat. You get a negative result. Take a fresh sample and add heat with dilute acid. Bring to the boil. This hydrolyses it! Then, neutralise it with an alkali and test with pH paper. Add Benedict's and heat again. If non reducing sugars are present, clear colour change from blue to an orange red precipitate.
Enzymes
Enzymes are protein molecules that act as biological catalysts. An enzyme catalyses a specific reaction. They have an active site… Substrate ENZYME Products. Maltose is broken down by the enzyme maltase to glucose and glucose. The reactions enzymes catalyse can be anabolic or catabolic - Anabolic meaning building, catabolic meaning breaking down. They do not die. They are simply denatured. They are affected by temperature, pH and concentration of enzyme and/or substrate. They can be affected by inhibitors. NON COMPETETIVE ARE THINGS THAT STICK IN THE SIDE. COMPETETIVE FIT IN ACTIVE SITE AND ARE COMPLIMETRY IN SHAPE
The structure of an enzyme
Enzyme molecules tend to be 100’s of amino acid long. They are named ‘globular proteins’. They are arranged with charged ‘R’ groups pointing outwards so they dissolve in water. They have a complex tertiary structure. One region of this is where the substrate fits. This is called the active site.
The active site is complimentary
Biochemical Tests:
Proteins - add biurettes reagent to the sample. If protein is present, clear colour change from blue to purple.
Reducing Sugars – add Benedict’s reagent to the sample. Heat in Bunsen or water bath. If reducing sugars are present, clear colour changes from blue -> orange red precipitate.
Lipids – dissolve sample in ethanol. Slowly pour the solution into the water slowly. If lipids are present a white emulation forms on the surface.
Starch – add iodine solution to the sample. If starch is present clear colour change from orange red to blue black.
Non reducing sugars – do the reducing sugars test. Add Benedict's to the sample & heat. You get a negative result. Take a fresh sample and add heat with dilute acid. Bring to the boil. This hydrolyses it! Then, neutralise it with an alkali and test with pH paper. Add Benedict's and heat again. If non reducing sugars are present, clear colour change from blue to an orange red precipitate.
Enzymes
Enzymes are protein molecules that act as biological catalysts. An enzyme catalyses a specific reaction. They have an active site… Substrate ENZYME Products. Maltose is broken down by the enzyme maltase to glucose and glucose. The reactions enzymes catalyse can be anabolic or catabolic - Anabolic meaning building, catabolic meaning breaking down. They do not die. They are simply denatured. They are affected by temperature, pH and concentration of enzyme and/or substrate. They can be affected by inhibitors. NON COMPETETIVE ARE THINGS THAT STICK IN THE SIDE. COMPETETIVE FIT IN ACTIVE SITE AND ARE COMPLIMETRY IN SHAPE
The structure of an enzyme
Enzyme molecules tend to be 100’s of amino acid long. They are named ‘globular proteins’. They are arranged with charged ‘R’ groups pointing outwards so they dissolve in water. They have a complex tertiary structure. One region of this is where the substrate fits. This is called the active site.
The active site is complimentary