1. Lab 2: Cells

2. Which one of the following substances is not a lipid?
A) wax  
B) cholesterol  
C) cellulose  
D) steroids  
E) triglycerides  

3. You now know that the old cliche "oil and water don't mix" is true. Why?
A) Oil exhibits polarity and water does not.  
B) Water exhibits polarity and oil does not.  
C) Oil is hydrophilic.  
D) Water is hydrophobic.  
E) Oil is an organic compound and water is not.  

4. A molecule with the formula C55H110O55 is probably a(n)
A) oil.  
B) steroid.  
C) wax.  
D) protein.  
E) polysaccharide.

5. All living things are made of cells
Cells are the basic unit of living things
All cells come from other cells
This is the classical cell theory

6. Cells are small Most bacteria are .5-2µm in size
Light microscope’s limit= ~500nm=.5µm
Single eukaryotic cells are larger, but still to small to see without magnification

7. Microscopes allow us to see the world of cells
Microscopes use multiple lenses to magnify small things

8. Measuring the world of the small
We use the metric system
The metric system uses powers of 10
Major metric prefixes are 1000-fold apart
English-Metric conversions:
1 meter = 1.09 yards
1 centimeter = .4 inches
Metric interconversions
1 m = 100 cm
1 cm = _____m

9. The Metric System Decimal system (powers of 10)
Base units (meter, gram) modified by prefixes:
kilo = thousand
centi (c) = hundredth 0.01
milli (m) = thousandth 0.001
micro (µ) = millionth
nano (n) = billionth

10. The Metric System How do you convert from one metric unit to another?
Each decimal place represents one power of 10.
1.0 meter =
100 or 102 centimeters (cm)
1000 or 103 millimeters (mm)
1,000,000 or 106 micrometers (µm or microns)
1,000,000,000 or 109 nanometers (nm)

11. The Metric System Example: 1.0 cm = ? m
Since a centimeter is a hundredth of a meter, it is 10x10 or 2 decimal places smaller than a meter.
So, move the decimal point 2 places to the left: 1.0 cm = 0.01 m

12. The Metric System Example: 1.0 cm = ? mm
First put both in terms of meters:
1.0 m = cm = mm
How many powers of ten (decimal places) are there between cm and mm?
If cm = mm, then
1.0 cm = 10.0 mm
So to convert from cm to mm, you must multiply by 10 (move the decimal point one place to the right).

13. Using a Light Microscope
Get microscope from cabinet
Carry with one hand holding arm and the other supporting the base
Arm
Base

14. Using a Light Microscope
1. Ocular (eyepiece)
6. Nosepiece
2. Arm
7. Objectives
8. Stage
3. Coarse focus knob
9. Stage clips
10. Diaphragm
4. Fine focus knob
11. Light source
5. Base

15. Calculating Magnification
Ocular lens (10X) x Objective lens

16. Field of View Actual diameter of microscope image at a certain mag.
As magnification increases, field of view _______.

17. Using a Light Microscope
Letter “e”
Practice steps for observing specimens
Draw what you see at different powers
Calculate total magnification
Silk threads
Get a sense of ‘depth of field’ (how deep can lenses focus at different powers)
Try to determine relative positions of threads (top, middle, bottom)

18. Cells can be placed into two categories
Prokaryotic and eukaryotic
Prokaryotic- smaller and simpler
Eukaryotic- larger and more complex
Eukaryotic- containing membrane-bound organelles

19. Observing Cells Onion Cells Cheek cells Elodea cells
Elodea cells (in salt water)
Pond water

20. Cell structures- Animal cell

21. Cell structures- Plant cell

22. Your instructions for the lab
1. Draw each subject in detail. Label 2 organelles.
2. Using field of view, estimate size of specimens.
3. On back of paper, compare and contrast:
Onion vs. elodea
Elodea in salt vs. elodea in fresh water
Plant vs. animal cells
4. Describe drawn pond water organism. What does it look like? Size? What do you think it is? Categorize it. Unicellular? Plant or animal? Etc.

23. Using a Light Microscope
Cleaning up:
Remove and return your slides.
Put the scanning objective in place and lower it all the way down.
Roll up the lamp cord neatly.
Carefully return your microscope to the shelf where you got it. .