Microscopy
Outline of the day
1. Turn in your lab reports at the front
–
More than 10 minutes late = bad
Any questions on last week’s lab?
Quiz
Introduction to the lab
Lab!
Check out
2.
3.
4.
5.
6.
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Get a stamp
Make sure I mark you down for attendance
Quiz
• Ends 8 minutes after it’s started
– Ends at: ____
Lab this week!
• Using the microscope to explore microscopic structures!
– Learning how to use a scope
• Parts of the scope
• Measuring the diameter of the field
– Plants
• Leaf cells
– Seeing chloroplasts, observing the results of osmosis
• Onion cells
– Seeing nuclei (with a stain)
– Animals
• Looking at your own cheek cells
– Mitosis
• Plant cells undergoing mitosis
• Animal cells undergoing mitosis
Our microscopes
• Bincocular, compound microscopes
– Expensive!
• Three lenses
– 4x (low power)
• ALWAYS start on this lens
– 10x
– 40x (high power, used last, if at all)
– (The eyepieces have a 10x lens in them as well, so
the total magnification is 10x greater than the amount
stated on the lens)
Parts of the scope
Missing image:
Labeled drawing of a scope.
Using the scope
1.
2.
3.
Put the scope on the 4x objective
Move the stage all the way to the bottom
Put the slide on the stage
•
4.
Using the coarse focus knob, slowly raise the stage until
the slide comes into focus
Use the fine focus knob to fine-tune the focus, and scroll
around on the slide to find the structure(s) you’re looking
for
If necessary, increase the scope to the 10x objective, and
use the fine focus to adjust the focus
If necessary, increase the magnification to the 40x
objective, using ONLY the fine focus to adjust the focus
5.
6.
7.
•
8.
A little clip should hold it in place
If the slide is in focus on the 10x objective, it should be in focus on
the 40x.
Remove the slide, put scope on 4x objective, and move
the stage to the bottom
Using a microscope
• A few key points
– You can run the stage into the lens; this is bad
• (you can break both the slide and the lens)
– Always start out on the lowest power possible,
get the item in focus there, and then slowly
increase magnification
First thing to do: look at a ruler
Examples
• Measure the width of the
field of view for each lens
CC licensed image: http://flickr.com/photos/merceblanco/209232584/
Elodea leaf
• This is approximately what you should see:
• Once you’ve seen that, put some salt-water
onto the slide, and observe the change
CC licensed images from: http://flickr.com/photos/zachdurland/369427527/
Onion cell
• Should look something like this:
• Nucleus is the large purple circle
– Nucleolus is the small dark circle inside this
CC licensed image: http://flickr.com/photos/faberitius/310545116/
Onion mitosis
• You’re looking at a
growing onion root tip
• Find a cell in each
stage of the cell cycle
– Most cells are in
interphase
– A few of the cells are
undergoing mitosis
CC licensed image: http://flickr.com/photos/uafcde/2233758/
Animal mitosis
• You’re looking at a
growing fish
embryo
• Find a cell in each
stage of the cell
cycle
– Most cells are in
interphase
– A few of the cells
are undergoing
mitosis
CC licensed images from: http://flickr.com/photos/uafcde/2233964/in/set-95396/; http://flickr.com/photos/uafcde/2257963/
Key points
• Take your time using the scope
– Be careful not to break anything!
– Always start on the 4x objective!
• When you put the scopes away
– Turn the light intensity all the way down, then turn it
off
– Wrap the cord around the base
– Be sure there are no slides on the stage
– Put the scope on the lowest objective
– Lower the stage all the way down
– Cover the scope with its plastic cover
Microscopes!
• Each table has its own set of slides
• You’ll need to find the structures on the slides
– Use your lab manual to figure out what you should look
at.
• Microscopes are in the cabinet in the back
• When you put the scopes away
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Turn the light intensity all the way down, then turn it off
Wrap the cord around the base
Be sure there are no slides on the stage
Put the scope on the lowest objective
Cover the scope with its plastic cover
Before you leave
• Clean up your work area
– Turn in your slide set (show me that they’re all there)
– Store your microscope
•
•
•
•
•
Turn the light intensity all the way down, then turn it off
Wrap the cord around the base
Be sure there are no slides on the stage
Put the scope on the lowest objective
Cover the scope with its plastic cover
• Show me your lab report so I can stamp it
– Need to have all data fields filled in
– Complete at home and then turn in at the beginning of next lab
• Remember that we’ll have a quiz at the beginning of the
next class
– 6-7 questions on today’s lab
– 3-4 questions on the lab we’ll do next week
Notes for the instructor:
• As these students are beginners at using a scope, I
show examples of all the structures during the
introduction. My goal here is to help them know what
they should be seeing. However, as I don’t want
students just copying what I’ve shown (the point is for
them to learn to use the scope and see the structures for
themselves), I _never_ go back to show those slides
again, even if asked. Instead, I help the students find
the structures on their own. Telling the students that this
is your policy up front will likely help.
• I hand out a copy of the “using the scope” slide to each
group before going over it in class; that way they can
keep it while using the scopes.
License information
• This work is licensed under the Creative Commons AttributionNonCommercial-ShareAlike 3.0 License. To view a copy of this
license, visit http://creativecommons.org/licenses/by-ncsa/3.0/us/ or send a letter to Creative Commons, 171 Second
Street, Suite 300, San Francisco, California, 94105, USA.
• The slides in this presentation were originally created by Marc
C. Perkins (http://faculty.orangecoastcollege.edu/mperkins).
• You are free to use, modify, and distribute these slides
according to the terms of the Creative Commons license (e.g.,
you must attribute the slides, no commercial uses are allowed,
and future distributions must be licensed under a similar
license).
• Attribution should be given to Marc C. Perkins (and any later
editors), including a link back to Marc’s current website. This
applies both while distributing the slides and during use of the
slides; attribution during use can be satisfied by, for instance,
placing small text on at least one of the slides that has been
shown (see below for an example).
History
• August 2007: Marc Perkins released first
version.
http://faculty.orangecoastcollege.edu/mperkins
(If you modify these slides and redistribute them, add your information to the list)