2.2 Test for biological Molecules Flashcards
steps to reducing sugar test
1) Add benedict’s solution to sample
2) Stir it & place in a water bath at 80 degrees for 3 minutes
3) Note colour change
why is there a colour change when testing for reducing sugars
- Reducing sugars gives electrons
- Reducing sugars give electrons to the Cu2+ ions, turning them into Cu which forms orange/red colour
How to carry out carbohydrate test
1) take iodine and add a few drops to the sample
2) If turns black starch is present
why does iodine cause colour change in starch
- The iodine ions forms a triiodide
- It then slips into helix of amylose and causes colour change
what is the steps for testing for non-reducing sugars
- First test for RS
- Take a separate sample & boil it with HCL to hydrolyse sucrose into glucose + fructose
- Cool Solution
- Add Soduim Hydrogen Carbonate to neutralise it
- Test for RS
How to carry out test for lipids
- Take a sample & mix throughly with ethanol & shake
- Filter & add water
- Cloudy precipitate indicates presence of lipids
How to carry out test for Proteins
- Add buiret solution
- Forms liliac colour
why does colour change in protein test
The colour change is formed due to a complex being formed by the Nitrogen atom in peptide chain and the Cu2+
calorimetry
Piece of equipment used to quantitatively measure absorbance or transmission of light by a colored solution.
6 steps to calorimetry
Filter is placed in colorimeter.
Calorimeter is then calibrated using distilled water.
Benedict’s test is performed on a wide range of known concentrations of glucose.
Solutions are filtered to remove precipitate
% transmission of each solution is measured.
The calibration curve is then plotted.
what is a biosensor
Using biological components to determine the presence and concentration of molecules such as glucose.
3 steps to biosensor
1) Molecular recognition: Single strand of DNA or protein which are complementary to test sample is immobilised. When sample is added, it will bind to DNA/protein
2) Transduction: This binding causes change in a transducer, resulting in an electronic current.
3) Display: This current is processed to determine the concentration of sample present.
what is Thin Layer Chromotography
Technique used to seperate the individual components of mixture
what is the stationary phase
Silicia gel is applied to chromotography paper & then amino acids are then added to one end
what is the mobile phase
organic solvent moves up chromotography paper resulting in amino acids moving different distances