Required practicals 3 and 4 Flashcards
Potassium permanganate experiment, gel electrophoresis, acids and bases.
Calculate the molecular weight of KMnO4.
K = 39 g/mol
Mn = 55 g/mol
O = 16 g/mol
158g/mol
Calculate the number of moles required to make 250 ml of 100 mM KMnO4.
Give your answer in moles, to two significant figures.
0.025 mol
Now that you know how many moles of KMnO4 are required and you know the molecular mass of KMnO4 you should use your answers to the previous questions to calculate what mass of KMnO4 you require to make 250 ml of 100 mM solution.
3.95 g
How much 100 mM stock solution is required to make 100ml of 100 micromolar solution?
Give answer to 2.s.f. in ml.
0.10 ml
How do you dilute a concentrated acid?
Add the acid to the water.
When diluting a concentrated acid, what happens to the solution?
It will get hot.
When preparing a solution from NaOH pellets, what happens to the solution?
It will get hot.
What volume of concentrated (11.64 M) HCl is required to make 100 ml of 1 M HCl?
Give answer to one decimal place in ml.
8.6 ml
What should you do if you spill concentrated acid?
Rinse thoroughly with water.
What was the electrophoresis gel made of?
Agarose.
Why did we wear gloves to deal with KMnO4?
It is a powerful oxidising agent and will react quickly on skin. This will leave an insoluble brown stain of MnO2 which is not dangerous but will take a couple of days to fade.
Why is the weighing boat rinsed into the beaker?
To ensure all KMnO4 is transferred.
Why are the beaker and funnel also rinsed with distilled water?
To ensure complete transfer of MnO4.
How was the stock solution/dilutions of KMnO4 solution disposed of?
Stock = waste bottle.
Dilutions = down the sink with the tap running (to make waste as inert as possible).
Give the equation relating volume and concentration in terms of dilutions.
C1V1 = C2V2
(initial concentration x initial volume = new concentration x new volume)
What must be done before making/modifying corrections to the electrophoresis tank?
The power supply is switched off.
What must the buffer not spill over?
Leads and connections to the power supply.
Name the components of a gel electrophoresis tank.
Sample wells
Anode
Cathode
Power supply
Buffer solution
Agarose gel
Why is gel electrophoresis commonly used in molecular biology?
To separate DNA molecules, RNA molecules and protein molecules in complex mixtures according to their size and charge properties.
How are the sizes of the separated molecules estimated?
When molecular weight markers are run alongside samples.
When is agarose gel electrophoresis commonly used?
To separate DNA molecules.
How are the DNA molecules separated?
Negative DNA molecules pulled through agarose matrix within an electric field.
Shorter molecules move faster than longer ones.
List a property, other than the length of DNA molecules that is an important factor in migration rate.
The conformation (shape) of the DNA.
(Circular plasmids migrate the slowest and supercoiled move the fastest).
The voltage applied to the gel.
(Higher voltages give faster migration).
How are small DNA molecules separated?
Increasing the concentration of agarose gel so the migration speed is reduced.