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Microscopes

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by

Phuong Nguyen

on 8 June 2015

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Transcript of Microscopes

Light Microscopes
Microscopy
Parts of Compound Light Microscope Cont...
Magnification and Resolution
Electron Microscopes
Pros:
Can magnify over 500,000 times
(125 times the magnifying power of light microscopes)
Can resolve objects that are 0.2nm apart (1000 times the resolving power of light microscopes)
Clear images
Cons:
Requires cells to be killed and chemically treated
Expensive and requires training
No color can be seen
Pros and Cons
Magnification =
measured length/ scale bar label
Actual Size=
measured length/magnification
Drawing Magnification =
drawing size/ size of specimen
Tips
1. Make all units the same
2. Round answer to nearest whole number
Calculating Microscope Problems
Actual Size given only micrograph and magnification
Actual Size given micrograph and scale bar
The Basics
Answer to previous sample
Written Style Questions
Uses a light source to produce an image of a specimen, which is called a micrograph
Micrograph produced is upside down and backwards from the specimen
Compound light microscopes magnify up to 2000x
Can study stained or living cells in color
Stains make it easier to view details of the specimen
Resolves objects 200 nm apart
Magnification: The size of the viewed object compared to its actual size
Magnification= power of eyepiece x power of objective
Resolution: The clarity of an object as a result of separating components that are close together
Video
Uses electrons that pass through a specimen in order to produce a micrograph
Magnifies over 500,000x
Have around 1,000x the resolving power of light microscopes
Micrograph are colorless (only black and white image)
Specimens must be dead


Types of Electron Microscopes
Scanning Electron Microscope (SEM)
Ideal for studying the surface of cells
Micrographs look three dimensional and are colorless
Transmission Electron Microscope (TEM)
Ideal for examining the interior of cells: organelles in detail, chromosomes, strands of cellular DNA

Enzo di Fabrizio
Paramecium
Magnification: 500x
1. Using a ruler, measure the length of the specimen at its longest point in millimeters
2. Divide measured length by magnification
3. Convert answer in mm to micrometers: multiply by 1000
4. Round to nearest whole number

Worked Calculation
of previous sample
*Length of paramecium
(41 +/- 1)
Britney Spears views an image of an
erythrocyte
that is magnified at 20,000x. The micrograph of the cell is 110mm long. What is the actual length of the specimen?
Worked Calculation for previous sample
Parts of a Compound Microscope
Eyepiece
- The lens the viewer looks through: 10x or 15x
Objective lenses
- Allow different magnification: 4x, 10x, 40x
Oil Immersion lens:
100x
Light Source
- Allows in light to see the slide
Stage
- Where the slide is placed
Stage clip
s- Holds the slide in place

IB Style Question

Courtesy of IBO
Answer to Previous Sample
a.
I. Capsid, protein coat, or capsomere
II. DNA

b.


Diaphragm
- Controls the amount of light that goes through
Coarse Adjustment
- The large knob that causes large changes in focus
Fine Adjustment
- The smaller knob that causes small changes in focus
Body Tube
- Holds eyepiece and lenses in place
Nose Piece
- Holds objective lenses and allows one to change them
Parts of Compound Microscope Cont...
Base
- Supports the microscope
Arm
- Supports the upper part of the microscope *To carry a microscope, carry it by the base and the arm
Pros and Cons
Pros:
Inexpensive
Easy to use, requires little training, and portable
Specimens require little preparation time
Can study dead or living cells in color
Objects can be magnified up to 2000x
Cons:
Cannot view small specimens, such as viruses, molecules, and atoms
Cannot magnify more than 2000x
Field of View
The diameter of the circle you see in the microscope.



If a 5x FOV is 3mm, what is the 40x FOV of that microscope?
Cheek Cell
What organelles can we see?
GAME TIME!
What part of a light microscope is this? Also, what is the function?
Which microscope is able to view chloroplasts?

If a 10x FOV is 2mm, what is the 100X FOV of that microscope?
Which type of microscope was able to capture this micrograph of pollen grains?
What microscope was able to capture this micrograph? *Look familiar?
True or False?

Micrographs
are only created by electron microscopes.
If the magnification of an eyepiece is 15x and the objective lens is 20x, what is the total magnification of the specimen viewed?
What does the Diaphragm do?
Which microscope requires a dead specimen?
FINAL QUESTION!

How do you carry a compound microscope?
Always begin examining microscope slides with what power objective?
Full transcript