Evans' Lesson Flashcards
(22 cards)
What is an organelle ?
A type of sub-cellular structure
Who was the first to observe cells under a microscope ?
In the 1960s Robert Hooke was the first to describe cells after he observed them under a microscope he had made
What is Magnification?
This is the degree to which the size of an image is larger than the larger the object itself. It can be expressed as x1.5, x10 etc.
What is Resolution ?
This is the degree to which it is possible to distinguish between 2 objects that very close together. The higher the resolution, the greater detail you can see.
Magnification Calculation?
Image Size / Actual Size
Total Magnification Calculation ?
Eyepiece Magnification x Objective Magnification
I = AM
What magnifications are on the light microscope?
x4, x10, x40, x100
What is the maximum magnification a light microscope can get?
x1500
What is the maximum resolution a light microscope can get?
200nm
- This means that if 2 objects are closer than 200nm they will be seen as 1 object. The limit is due to the size of the wavelength of light- w objects can only be distinguished if the light waves can pass between them
What stain is used for DNA?
Acetic Orcein
Stains DNA red
What stain is used on cheek cells ?
Methylene Blue (stains cheek cells blue)
What is Staining?
These are coloured chemicals that bind to chemicals on or in the specimen and allow it to be seen.
What is Sectioning ?
Specimens are embedded in wax and then thin sections are cut without distorting the structure. This is very useful for making sections of soft tissue the brain or lung.
What is a Graticule?
A small transparent ruler fitted in the microscope’s eyepiece
(About 1 cm)
What is the unit for the eyepiece graticule scale?
Eyepiece Units (epu) - They are Arbitrary (not of a fixed length) ~ they represent different lengths at different magnifications
What is the Cell Ultrastructure ?
The detail inside of cells seen with electron microscope
What are two types of Electron Microscopes?
Transmission Electron Microscope (TEM) and Scanning Electron Microscope (SEM)
Which Electron Microscope is the most powerful; the Transmission Microscope or the Scanning Microscope
The Transmission Microscope
What is the maximum magnification for the Transmission Electron Microscope?
x500,000
What is the maximum resolution in a Transmission Electron Microscope?
0.1nm
What is the maximum magnification in the Scanning Electron Microscope ?
x100,000
What is the maximum resolution in the Scanning Electron Microscope?
10nm
