A typical plant cell may be about 0.1mm in diameter and an animal cell 0.02mm in diameter. Prokaryotic cells are smaller-often about 0.002mm long.
It is not possible to see cells as separate objects using the naked eye. The ability to see two or more objects as separate objects is called resolution.
Light microscope
Developed in the late 16th century, gave greater resolution than the human eye, allowed scientists to see plant,animal and bacterial cells
Electron microscope
Passes electrons through the specimen, can give much better resolution, allows seeing sub-cellular structures in finer detail
Required practical: Use a light microscope to observe, draw and label a selection of plant and animal cells
1. Place tissue sample on slide
2. Add stain
3. Lower coverslip
4. Place slide on microscope stage
5. Focus using low power
6. Change to high power and refocus
7. Draw cells
8. Add scale line
Magnification
How many times larger the image is than the real object
Bacteria use binary fission to multiply, can do so as frequently as once every 20 minutes if they have enough nutrients and suitable temperature
In school/college, cultures should be incubated at max 25°C to reduce likelihood of harmful bacteria growth. In industry, higher temps can be used for faster growth.
Precautions to prevent bacterial culture contamination
