Fichas
Biochemical Tests for Molecules
Fichas del conjunto (22)
- 1What does the biuret test test for?Proteins
- 2What does the iodine test test for?Starch
- 3What does the emulsion test test for?Lipids
- 4What does the Benedict's test test for?Reducing and non-reducing sugars
- 5What do test strips test for?Glucose
- 6Outline the method of the biuret test1. Add NaOH solution (test solution must be alkaline)
2. Add copper (II) sulphate - 7What are the results of the biuret test?POSITIVE = purple
NEGATIVE = blue - 8Outline the method of the iodine testAdd iodine dissolved in potassium iodide solution
- 9What are the results of the iodine test?POSITIVE = dark, blue-black
NEGATIVE = browny-orange - 10Outline the method of the emulsion test1. Shake the test substance with ethanol for a minute
2. Pour the solution into water - 11What are the results of the emulsion test?POSITIVE = milky solution
NEGATIVE = clear solution - 12Outline the method of the Benedict's test for reducing sugars1. Add Benedict's reagent (blue)
2. Heat in a water bath - 13What are the results of the Benedict's test for reducing sugars?POSITIVE = green --> yellow --> orange --> brick red precipitate
NEGATIVE = blue (non-reducing sugar may be present) - 14Outline the method of the Benedict's test for non-reducing sugars1. Add dilute HCl (breaks non-reducing sugar down to monosaccharides)
2. Heat in water bath
3. Add NaHCO₃ (neutralises solution)
4. Add Benedict's reagent
5. Heat in water bath - 15What are the results of the Benedict's test for non-reducing sugarsPOSITIVE = green --> yellow --> orange --> brick red precipitate
NEGATIVE = blue (no non-reducing or reducing sugar present) - 16Outline the method of using test strips1. Strips are dipped in test solution
2. Compare colour change to a chart - 17Complete the sentences: A ____________ is a device that measures the strength of a coloured solution by seeing how much _______ passes through it. It measures _______ (the amount of light absorbed by the solution). The more _______ the colour of the solution, the _______ the absorbance is.A COLORIMETER is a device that measures the strength of a coloured solution by seeing how much LIGHT passes through it. It measures ABSORBANCE (the amount of light absorbed by the solution). The more CONCENTRATED the colour of the solution, the HIGHER the absorbance is.
- 18Outline the method to find the glucose concentration of an unknown solution1. Make up several solutions of known glucose concentrations
2. Measure the absorbance of these solutions
3. Plot these absorbances on a graph to make a calibration curve - 19Outline the method of serial dilution (using 40mM sucrose solution)1. Line up 5 test tubes
2. Add 10 cm³ of the initial 40 mM sucrose solution tot he first test tube and 5 cm³ of distilled water to the other four test tubes
3. Using a pipette, draw 5 cm³ of the solution from the first test tube, add it to the second test tube and mix thoroughly
4. Repeat this process to create solutions of 10 mM, 5 mM and 2.5 mM - 20Outline the method for measuring the absorbance of known solutions1. Do a Benedict's test on each solution (plus a negative control of pure water)
2. Remove any precipitate (centrifuge or leave for 24 hours)
3. Switch the colorimeter on and allow 5 mins to stabilise
4. Set up the colorimeter with a red filter
5. Add distilled water to a cuvette
6. Put the cuvette into the colorimeter
7. Calibrate the machine to zero
8. Use a pipette to transfer a sample of the solution from the first test tube to a clean cuvette
9. Put the cuvette in the colorimeter and measure absorbance
10. Repeat steps 8-9 for the remaining solutions - 21What is a biosensor?A device that uses a biological molecule (e.g. enzyme) to detect a chemical
- 22How does a biosensor work?The biological molecule produces a chemical signal, which is converted to an electrical signal by a transducer.
The electrical signal is processed and can be used to work out other information.
Información
- Descripción
- El usuario ha eliminado su información de asignaturas Fichas sobre Biochemical Tests for Molecules, creado por Usuario eliminado el 05/03/2018.
- Creado por
- Usuario eliminado · mar 2018
- Actualizado
- 5 mar 2018
- Visitas
- 43
- Historial
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- Creado por Yinka F · 24 ene 2018
- Copiado por Yinka F · 5 mar 2018
- Valoración