Methods Of Studing Cells Flashcards
What are microscopes?
Instruments that produce a magnified image of an object.
What is the resolution of a light microscope?
0.2 micrometers.
What is the resolution of an electron microscope?
0.1 nanometers.
What is the magnification of an object?
How many times bigger the image is when compared to the object.
What is the equation for magnification?
Magnification = size of image/size of real object.
What is the resolution of a microscope?
The minimum distance apart the two objects can be for them to appear separate.
What does the resolution depend on?
The wavelength or form or radiation used.
What does it mean if a microscope goes beyond its limit of resolution?
Increasing the magnification will not reveal more detail to an object.
What is cell fractionation?
The process where cells are broken up and their different organelles are separated.
Why is the tissue placed in a cold solution before cell fractionation can begin?
To reduce enzyme activity that might break down organelles.
Why is the tissue placed in a buffered solution before cell fractionation can begin?
So the pH does not fluctuate and alter the structure of the organelles or functioning of enzymes.
Why is the solution in cell fractionation the same water potential as the tissue?
To prevent osmosis resulting in organelles bursting.
What are the two stages of cell fractionation?
Homogenation and ultracentrifugation.
What are cells broken up by?
A homogeniser (blender).
What does the homogeniser do?
Releases the organelles from the cell.
What is the homogenate?
The resultant fluid from the homogeniser.
Why is the homogenate filtered?
To remove any complete cells and large debris.
What is ultracentrifugation?
The process where the fragments in the filtered homogenate are separated in a machine called a centrifuge.
What does a centrifuge do?
Spins tubes of homogenate at a very high speed to crate a centrifugal force.
How is the tube of filtrate in the centrifuge spun to start with?
At a low speed.
What happens to the organelles as they are spun in the centrifuge?
The heaviest organelles are forced to the bottom of the tube.
What is formed at the bottom of the tube in the centrifuge?
A thin sediment or pellet.
What is the supernatant?
The fluid at the top of the tube in a centrifuge.
Where is the supernatant transferred to?
Another tube.
What happens to the supernatant that has been transferred?
Its spun in the centrifuge at a faster speed than before.
What happens as the centrifuge increases in speed with each newly transferred supernatant?
The next heaviest organelle is sedimented and separated.
