Chapter 3: Cell Structure Flashcards
What is a cell?
the basic unit of life
What is a microscope?
instruments that produce a magnified image of an object
What is the object in microscopy?
The material place under the microscope, that is being magnified.
What is the image in microscopy?
the magnified appearance of the material viewed under the microscope
What is the magnifcation?
How many times bigger the image is compared to the object.
How do you calculate the magnification?
magnification= image/ object
How many meters in Kilometers?
1x10^(3); 1000
How many metres in a millimetre?
1x10^(-3) ; 0.001
How many meters in a micrometre?
1x10^(-6); 0.000001
How many metres in a nanometre?
1x10^(-9); 0.000000001
What is the rule with the magnification equation?
the image size and object size have to be in the same units
What is the resolution/ resolving power?
the minimum distance apart two objects can be in order for them to appear as separate items
What is the resolving power of a light microscope?
0.2μm
What is the benefit of a greater resolution?
it has a greater clarity making the image produced clearer and more precise
What is Cell fractionation?
the process where cells are broken up and the different organells they contain are separated out.
Why is cell fractionation needed?
to obtain large numbers of isolated organells so the function and structure can be studied.
What solution does tissue have to be placed in before cell fractionation?
a cold, buffered solution of the same water potential.
Why does the solution the tissue is place in for cell fractionation have to be cold?
to reduce enzyme activity that might break down the organells.
Why does the solution the tissue is place in for cell fractionation have to be buffered?
so that the pH doesn’t fluctuate, which could alter the organells structure.
Why does the solution the tissue is place in for cell fractionation have to be the same water potential?
to prevent organells from bursting or shrinking as a result of osmotic gain or loss of water
What are the two stages of cell fractionation?
Homogenation and ultracentrifugation
What is Homogenation?
When the cells are broken up by a homogeniser (blender), releasing organells from the cell resulting homogenate which is filtered to remove debris.
What is ultracentrifugation?
the process by which the fragments in filtered homogenate are separated by a centrifuge.
How does the centrifuge separate the organells in the homogenate?
the centrifuge spins the homogenate at a slow speed, the heaviest organells are forced to the bottom of the tube forming a sediment separate to the remaining fluid (supernatant). the supernatant is separated and spun again at a higher speed.