Scientific Tools
&
Techniques
Compound Light Microscope
• Uses light
• Image appears upside down and backwards
• Under Low Power field of view is larger (4 times)
• Under High Power field of view is smaller (4 times)
How will the f appear in the field of
view of a compound microscope?
Upside Down and Backwards
FOV in Low Power:
4 cells are visible
How many cells will be visible in
high power?
FOV in High Power:
1 cell is visible!
Microscope Rules:
• Always start with low power
– Field of view is large and bright
– Helps you find specimen
– Use the coarse adjustment knob to focus
• Switch to High Power to see detail
– Adjust diaphragm (light) for smaller field of view
– Field of view is smaller and darker
– Helps see fine detail
– Only use fine adjustment knob to focus
Total Magnification:
Eyepiece # X Objective # = Total Magnification #
• What is the highest total
magnification in this
diagram?
• Answer:
10 X 40 = 400x
Eyepiece 10x
40x
10x
What is the total magnification
under low power in the diagram?
Eyepiece 10x
Answer:
40x
10 X 10 = 100x
10x
Electron Microscope
• A major breakthrough because they can magnify
250,000 x’s
• Shows much more detail than compound light
microscopes
• Shows great detail of inner structures
Ex) The inside of mitochondria in a cell!
Microdissection
tools/instruments
• Special micro-tools (very tiny)
• Used to take apart cells
• Ex) Removing a nucleus from one cell and putting
inside another cell!
• Used in genetic engineering
Use of Staining
• Staining allows for cell parts to be seen
• The nucleus for example becomes more visible
under the microscope when a stain is used
• Iodine is often used to stain cells
Centrifuge (Ultracentrifuge)
• Spins at high speeds to separate substances
by density
• Heavier particles end up in the bottom of
the test tube
Chromatography
• Separates colors
• Chromatography paper is used
• Ex) Plant pigments can be separated using
chromatography
Gel Electrophoresis
• Used to separate bands of DNA
• DNA bands of different sizes move at different
rates
– DNA bands move because of the charge
• Used in forensic investigation (CSI)
• Also used to determine paternity
Gel Electrophoresis
• How do you know these samples are from
different people?
• What’s responsible for the movement of
DNA?
Which two species of bear are most
similar?
How do you know?
Which direction should the slide be
moved to center the cell?
The diagram below shows the letter h
under low power, which diagram
shows the high power field of view?
1.
2.
3.
4.
How many micrometers in diameter
does each cell measure?
How many millimeters in diameter
does each cell measure?
In which direction should the slide be
moved to center the cell?
Name 2 unsafe practices shown below.
Which lab technique was used to
separate the substances in the test
tube?