Methods Of Studying Cells

Question 1

What is magnification

Answer 1

It’s how much bigger the image is than the specimen

Question 2

What is resolution

Answer 2

Is how detailed the image. It’s how well a microscope distinguished between 2 points that are close together

Question 3

What is the formula for magnification

Answer 3

Magnification = size of image / size of real object

M=I/a

Question 4

Before cell fractionation can take place, what must the solution be like

Answer 4

Cold- to reduce enzyme activity that might break down the organelles

Is of the same water potential as the tissue- to prevent organelles bursting or shrinking as a result of osmotic gain or loss of water

Buffered - so that the pH does not fluctuate. A change in pH could alter the structure of the organelles or affect the functioning of enzymes

Question 5

What’s the first stage in cell fractionation

Answer 5

Homogenisation - cells are broken up by a homogeniser, this releases the organelles from the cell. It is then filtered to remove any complete cells and large pieces of debris

Question 6

What is the second stage of cell fractionation

Answer 6

Ultracentrifugation- is the process by which the fragments in the filtered homogenate are separated in a machine called a centrifuge.

Question 7

What’s the process of ultracentrifugation

Answer 7

The tube of filtrate is placed in the centrifuge and spun at slow speed.

The heaviest organelles, thin nuclei, are forced to the bottom of the tube, where they form a pellet

The fluid at the top of the tube (supernatant) is removed leaving just the sediment of nuclei

The supernatant is transferred to another tube and spun in the centrifuge at a faster speed than before

The next heaviest organelles, the mitochondria, are forced to the bottom of the tube

The process is continued in this way so that, at each increase in speed, the next heaviest organelle is sedimented and separated out