Download Change of Venue - Higher Education Academy

Cells
Available through the Centre for Bioscience
www.bioscience.heacademy.ac.uk/resources/projects/tierney.aspx
Anne Tierney, University Teacher
Room 938, Boyd Orr Building
[email protected]
Intended learning outcomes
• Know what constitutes a cell
• Describe a typical cell
– Prokaryote
– Eukaryote
• Animal
• Plant
• Calibrate a light microscope
• Measure cells using a light microscope
What is a cell?
• Get into groups of two or three
– You have five minutes to think of everything
you can that defines what a cell is
– Feed back to the class
Types of cell - prokaryote
• Prokaryote
The most
common
shapes of
prokaryotes
a. Cocci – round
b. Bacilli – rod-shaped
c. Spiral
Types of cell - eukaryote
• Eukaryote
A eukaryotic cell - animal
A eukaryotic cell - plant
How do we measure cells?
• Cells are (usually) too small to see with the
naked eye
• Visualised with a microscope
• How can we measure with a microscope?
– Done indirectly
– Comparing a known scale with a scale that can
be calibrated
Measuring cells
• eyepiece graticule
• stage micrometer
How do we do it?
• We compare the known scale (stage
micrometer) to the scale that is to be
calibrated
Calibrating the eyepiece graticule
• The eyepiece scale is UNKNOWN
• The stage scale is KNOWN
– 100 stage divisions = 10mm
• Calibration must be done for every
magnification
Calibrating the eyepiece graticule
•
•
•
•
•
•
100 eyepiece divisions = ____ *stage divisions
We know that 100 stage divisions = 10mm
1 stage division = ____mm
____ *stage divisions = ____mm
100 eyepiece divisions = ____mm
1 eyepiece division = ____ mm or ____μm
• Repeat this for each magnification