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Methods of studying cells - Coggle Diagram
Methods of studying cells
Magnification
Magnification is how much larger an image appears to be compared to its actual size.
Actual size = Image size divided by Magnification
Resolution
An important factor determining the usefulness of a microscope is its resolving power or resolution.
Resolving power is a measure of the clarity of the image. It is the minimum distance two points can be separated and still be distinguished as two separate points.
Measuring cell sizes
To measure the size of cells on the microscope we use an eyepiece graticle.
However, this is an arbitrary scale. It needs to be calibrated for each microscope to be of ant use.
Count the number of eye piece graticle (epg) divisions = x
Count the number of micrometre divisions = y
One micrometre division is 0.1mm
Total width = y x 0.1mm
If there are x epg divisions
So x epg divisions = y x 0.1mm
Then one epg division = (y x 0.1) divided by x mm
Cell ultracentrifugation
The cells are homogenised (put in a blender) and then repeatedly centrifuged.
Each time the solution separated into a pellet and solution (supernatant).
The supernatant is then spun at a faster speed than before.
Pellet 1
Whole cells, nuclei and cytoskeletons
Pellet 2
Mitochondria and peroxisomes
Pellet 3
Microsomes, lysosomes and small vesicles
Pellet 4
Ribosomes, viruses and large macromolecules