Cells Observed in Lab Exercise 2 Cheek Cells Low power High power Onion Epidermis Scanning power Low power High power High power with labels Elodea Sprig, cells, organelles, etc. -   Cells  -  high magnification cyclosis -  mpg movie http://www.pearson-college.uwc.ca/pearson/biology/cyclos3.mpg

Microscopy

• Microscope -- images + discussion silk thread, letter e
• Preparing microscope slides Onion and cheek
• Cyclosis in Canadian Pondweed   gif   http://www.microscopy-uk.org.uk/mag/artnov00/dwelodea.html
• Cyclosis measurement mpg- http://www.pearson-college.uwc.ca/pearson/biology/cyclosis.htm
• Animations and videos - http://www.fed.cuhk.edu.hk/~johnson/animations/animations.htm
• Microscope slide images    Botany
• Letter e  air bubbles, etc.
• Scale and Magnification.
• Virtual microscopy
• Microscopy primer
• Microscopy & Imaging  WWW Resources including advanced techniques
• Microscopy Resources on the Web

 

Our Microscope

 


	The image at the left shows one  of the microscopes used in  Principles of Biology  Laboratory.
Bio. 1000 Microscope
	Nosepiece and objective lenses    Scanning Power 4 X Low Power 10 X High Power 43 X
Lamp and iris diaphragm  beneath stage of microscope
	Slide clipped on stage
Adjusting light with iris  diaphragm
Clean eyepiece	Clean Objective Lenses

Cells - Background Information

• Cell biology Problem sets and tutorials
• Cell organelles - Shockwave
• Cell  U. Maryland - lecture
• Virtual cell -- Check it out!
• Dictionary of Cell Biology  also
• Cells Alive Images and animation : Bacteria, HIV, Parasites
• Electron Microscope Gallery Virus, bacteria, fungi, algae, plants, animals
• Inside a Eukaryotic Cell
• Online Biology book - cell
• Virtual library of cell biology -

Questions

 

1. What characteristics did all of the cells which you observed have in common?

Hint: Consider things such as appearance (size, color, shape, organelles, etc.), behaviors (movements, responses to stimuli, growth, etc.), metabolic processes (anabolic and catabolic processes, energy transformation) chemical composition and other characteristics of life and living.

2. In what respects do animal cells (e.g., human mouth epithelium) differ from plant cells (onion root and Elodea leaf epidermis)?

Hint: Try to distinguish general differences between cells of the animal kingdom and the plant kingdom rather than specific differences of the one animal cell (human cheek cell) and two plant cells (leaf epidermis of onion and of Elodea. You may wish to check your text to learn what characteristics do distinguish Animalia from Plantae.

3. Do you think that most plant and animal cells are similar to those we observed today?

Hint: All three cells observed were from tissues at the surface (epidermis, epithelium) and both plant cells were from kinds of leaves. Would you expect cells of wood, roots, muscle, bone, blood, and nerve to be constructed in any particular way to allow them to perform specialized functions. Would you expect cells of more primitive organisms (sponges, mosses) to be similar?

4. What disadvantages might there be to studying cells which have been treated with dyes or stains?

Hint: Think of aspects of cells that might be different in cells treated with dyes or stains.

5. What are the advantages of studying cells that have been treated with dyes or stains?

Hint: Contrast the appearance of nuclei and cytoplasm of cheek cells, unstained vs stained with methlene blue. Consider also the stains used in electron microscopy

Tips

1. be prepared
• Read exercise 2 prior to lab
• Bring slides, coverglasses, ruler, and a calculator to lab
• Review the images on this page as well as those in your text
2. follow the directions when making microscope slide
• Clean the slide and coverglass
• Do not allow cells to dry even for a brief time
• Keep the sample specimen thin (a few cell layers at most)
• After you add the coverglass adjust the amount of fluid. Liquid should reach all edges of the coverglass, yet the coverglass should not float nor move with vibrations of the table
3. follow the directions when using the microscope
• Clean the lenses with lens paper
• Always -- this means every time -- start at the lowest magnification
• Never go to a higher power until you locate the specimen first at the lower power
• Center the specimen by moving the slide on the stage before you go to a higher magnification
• Adjust the fine focus while you observe the specimen.

Assignment

Check with your own instructor to learn the assignment for your section. The instructions here apply to students in sections 01, 02, 03 and 04 taught by Dr. Reid.

Do the exercise as written. Record all observations, make all measurements, and draw all cells and structures as directed in lab exercise 2.

In addition, show me each of the items listed on the handout that I will distribute in lab once you have the specimen in view and at the magnification requested. The actual list may vary slightly, but will probably include the following items:
 
 

Biology 1000                 Name    ______________________________


Lab #2                       Sect.  ____________________





                    CELL LAB





                          


A.  Use your microscope and follow the suggested procedures
    from the laboratory manual.   Locate each of the items listed
    below.  Show each item to me as described below.  I  will 
    initial the blanks to indicate you have shown it to me.

_________ 1. Letter slide (Right side up and filling field of view)

_________ 2. Silk thread sequence  Code on label =  A  B  C  D  E  F  

                    Top color      =    __________

                    Middle color   =    __________

                    Bottom color   =    __________

_________ 3. Cheek cell nucleus (Make two slides, one with no
            stain, one with methylene blue stain. Show 
            me the unstained nucleus at high power)

_________ 4. Onion cell cytoplasm (Don't cut, instead snap
             onion bulb leaf and peel a small (1 cm2) piece 
             of epidermis from inner leaf surface. Mount in drop of
             water on glass slide. Make sure the leaf
             surface is up.)  I may ask you to sketch what you are 
             viewing to so that I can be sure you know
             which part is cytoplasm, which part is cell wall, and 
             which part is vacuole.

_________ 5. Either the nucleus of an Elodea cell or cytoplasmic 
             streaming of the chloroplasts in an Elodea cell.


B.   Make an outline sketch of one onion cell or one Elodea
     cell on the back of this page. Make your sketch at least
     10 cm long. Just outline the cell, include no cell contents.

     Follow the steps on page 23-24 of the lab manual and
     also record the information below:


     III.      A  ______________________   mm

               B  ______________________   cells

               C  ______________________   mm

               D  ______________________   µm


              
      Based on your answers above, calculate how many times
      larger the sketch of the cell is than the actual cell.


Answer =  the sketch is ___________ times larger than the actual cell.


     NOTE AND CALCULATE THE INFORMATION REQUESTED BELOW


1.  Ocular magnification used for observation    =  ____________ times

2.  Objective magnification used for observation =  ____________ times

3.  Microscope magnification used for observation=  ____________ times

4.  How much larger (or smaller) is your drawing
    of the cell than the image of the cell you
    observe in the microscope?                   =  ____________ times

5.  How much larger is your drawing of the cell
    than the actual size of the cell observed?   = ____________ times

6.  Use a ruler and measure and record the length of your drawing
    of the cell and measure and record the width of your drawing of the
    cell.

   drawing length  =   ________ mm        


   drawing width  =    ________ mm


7.  Calculate the actual size of the cell you observed.  Calculate
both the length and the width of the actual cell.  Express the
length in millimeters, then convert that length to micrometers.  Express
the width in millimeters, then convert that width to micrometers.

actual length of


cell you observed  = __________ millimeters      = __________ micrometers

actual width of

cell you observed  = __________ millimeters      = __________ micrometers

Microscope Slides

	Label and coverglass up
Prepared Slide

Fresh mount

Add drop of water to clean slide
Add coverglass