3.1 Investigating the Structure of Cells Flashcards
What are microscopes?
Instruments that magnify the image of an object.
How do you calculate magnification?
size of image ÷ size of object
How do you calculate size of object?
size of image ÷ magnification
What is the resolution/resolving power of a microscope?
The minimum distance apart that two objects can be in order for them to appear as separate items.
What is the relationship between resolution and clarity?
Great resolution gives greater clarity.
What is cell fractionation?
The process where cells are broken up and the different organelles they contain are separated out.
What is the cell tissue placed in before cell fractionation?
A cold, isotonic, buffered solution.
Why is the solution cold?
To reduce enzyme activity that might break down the organelles.
Why is the solution isotonic?
To prevent organelles bursting or shrinking as a result of osmotic gain or loss of water.
What is an isotonic solution?
A solution that has the same water potential as the original tissue.
Why is the solution buffered?
To maintain a constant pH.
What are the two stages of cell fractionation?
Homogenation
&
Ultracentrifugation
What is homogenation?
When cells are broken up by a homogeniser, releasing the organelles from the cell. The resultant fluid is then filtered to remove complete cells and debris.
What is the name of the resultant fluid from homogenation?
Homogenate
What is ultracentrifugation?
The process whereby the fragments in the filtered homogenate are separated in an ultracentrifuge.
