BISC 133 Laboratory: Microscopes and Microorganisms – 2026 Final Study Guide

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BISC 133 LAB-MICROSCOPES AND ORGANISMS FINAL
STUDY ACTUAL MOTES SPECIFIC TO 2026 EXAM

Microscopes:

Parts of a microscope:
- Base
- Arm
- Stage
- Slide holder
- Course focus
- Oculars (10x)
- Nose piece
- Objectives (4x, 10x, 40x, 100x)
- Condenser
- Light source
- Light switch


What are the steps of focusing a
compound light microscope?

1. Click power switch to turn on light
2. Adjust light to appropriate brightness
3. Focus at 4X using coarse focus knob
4. Adjust ocular lenses to view one image
5. Focus using fine focus knob
6. Adjust the stage to move the slide to the center of microscope view
7. Put 10X objective in place
8. Focus using fine focus knob
9. Put 40X objective in place
10. Adjust using fine focus knob


Cladograms: a branching tree diagram
that shows ancestral relationships
among organisms. These diagrams show
evolutionary relationships between
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different branches referred to as clades.



Bacteria/Groups of Bacteria:

● Escherichia coli
- Gram negative
- bac shaped
- Can lead to E. coli: which causes diarrhea,
transmitted by fecal-oral route
- Model organism for gram negative bacteria.




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● Rhizobium spp.
- Gram negative
- Bacillus morphology
- Important for nitrogen fixation
- Live in root nodules of legume family of plants
● Nostoc spp.
- Gram negative
- Various cell shaped but mostly form long filaments
- Photosynthetic
- Can form macroscopic colonies
- Under low nitrogen conditions, it will form heterocysts.
● Treponema pallidum
- Gram negative
- Spirillum morphology
- Motile (moves in corkscrew motion)
- Causes syphilis
● Borrelia burgdorferi
- Gram negative
- Spirillum morphology
- Moves in corkscrew motion
- Causes Lyme disease
● Chlamydia trachomatis
- Gram negative
- Coccus morphology
- Obligate intracellular
parasites of humans
- Can cause a sexually
transmitted genital tract infection called chlamydia
- Can affect the eye causing a disease called trachoma.
● Bacillus spp.
- Gram positive
- Bacillus morphology
- Can produce endospores
- Model organism for gram positive
- Can cause disease anthrax
- Can be found in some soils, almost all are thermophiles.
● Staphylococcus aureus
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- Gram positive
- Coccus morphology, divide to form grape like clusters
- Part of microbial flora on skin and nose
- Under skin can cause pimples or boils, pneumonia,
meningitis, toxic shock syndrome. Infections can be
treated with antibiotics
● Streptomyces spp.
- Gram positive




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