1. What are they? What do they do? What do they look like?
Microorganisms
What are they?
What do they do?
What do they look like?

2. Microbiology Study of microorganisms
Organisms not visible with naked eye
Require magnifying glass or microscope
Includes wide variety of different organisms

3. Microorganisms are:
Bacteria
Viruses
Fungi
Protozoa
Animals

4. Microorganisms are Ubiquitous
Found virtually everywhere
Most are harmless
Some are beneficial
Used in research
Used to make foods (yeast, mold)
Used to make antibiotics

5. Light Microscope
Allows one to view most types of microorganisms (not most viruses)
Magnifies 40x – 1000x
Works by passing light through a series of glass lenses that bend or refract light rays
Microorganisms viewed may be living or fixed and stained to enhance visibility

6. Microscopy: The Instruments
A simple microscope has only one lens
This is A. Van Leeuwenhoek’s microscope from the 1600’s
Figure 1.2b

7. Parts of a typical light microscope

8. Electron Microscopes
Use beam of electrons, instead of light to magnify
Magnify up to 100,000X or more
Allow us to look inside cells and even see molecules

9. Units of Length
Light microscope can view objects measured in millimeters and micrometers
Electron microscope can view objects measured in micrometers and nanometers

10. Bacteria Prokaryotic cells Appear as different shapes
The genetic material in their cells is not contained in a nucleus
Appear as different shapes
Bacilli (rod-shaped)
Cocci (round)
Spirilla (spiral)
Most ubiquitous microorganism

11. Stained Bacteria

12. Bacterial Morphology Average size: 0.2 -1.0 µm  2 - 8 µm
Basic shapes:
bacilli
cocci
spirals

13. Usefulness of Bacteria
Decomposers: (“nature’s recyclers”) break down dead matter
Clean up the Earth’s land & water
Help with digestion
Make vitamins your body needs
Used to make medicines (insulin)
Food production: cheese, yogurt, sour cream, sauerkraut, pickles, etc.

14. Viruses
Tiny, nonliving particle that enters and then reproduces inside a living cell
Most are harmful

15. Characteristics of Viruses
Does not have all the characteristics essential for life
Viruses can only multiply when they are inside a living cell
Acts like a parasite
Parasite: an organism that lives on or in a host and causes it harm
Host: an organisms that provides a source of energy for a virus

16. Usefulness of Viruses Gene Therapy
Take advantage of a virus’s ability to enter a host cell
Gene therapy allows scientists to deliver needed genetic material to cells

17. Viruses, Bacteria, & Your Health

18. Pathogenic Microorganisms
Are harmful to humans
Able to cause pathology (damage) in host
- Invade host and damage tissue
Cause infectious disease
Disease that is transmitted from one source to another
Bacteria and viruses responsible for most infectious diseases

19. Infectious Diseases Can spread through contact with:
An infected person (touching, hugging, or kissing)
A contaminated object (sharing drinks or eating utensils)
An infected animal (an animal bite)
An environmental source (eating uncooked eggs or meat)

20. Common Infectious Diseases
Bacterial
Lyme Disease
Tuberculosis
Tetanus
Strep Throat
Viral
The cold
The flu
Cold sores
Chicken pox
AIDS

21. Streptococcal Skin Infection

22. Anthrax Lesion

23. Rash From Lyme Disease

24. Common Cold & The Flu Virus
Many different strains

25. Round virus
Chicken pox: causes an itchy rash on human skin

26. Bullet-shaped
Rabies virus infects nerve cells in certain animals

27. Viral Infection – Cold Sores

28. Treating Infectious Diseases
Bacterial Diseases
Antibiotics
Antibiotic resistance
Results when some bacteria are able to survive in the presence of an antibiotic
Viral Diseases
No medications that can cure viral infections

29. Vaccines
Important tools that help prevent the spread of infectious diseases
Vaccine: a substance introduced into the body to stimulate the production of chemicals that destroy specific viruses or bacteria
Made from dead or weak or altered viruses and bacteria

30. Fungi Eukaryotic cells
Can be multicellular molds or unicellular yeasts

31. Protozoa Unicellular eukaryotic organisms
Show various forms of motility
Flagella
Cilia
Pseudopodia

32. Animals Multicelluar Worms Small arthropods
Serve as vectors for disease transmission
Ectoparasites
Feed on blood by biting

34. Microscopy Microorganisms not visible with naked eye
Only visible with some method of magnification
Most microorganisms require a microscope to view them
Light microscope – provides 40X to 1000X
Electron microscope – provides 5000X to 500,000X

35. Measuring Microorganisms
Microorganisms, because of their small size, require small units of measurement
Micrometer (um) – is 1x10-6 meter or mm
Sufficient to measure bacteria, fungi, protozoa
Nanometer (nm) – is 1X10-9 meter or 0.001um
Sufficient to measure viruses and sub cellular particles

36. Units of Length
Light microscope can view objects measured in millimeters and micrometers
Electron microscope can view objects measured in micrometers and nanometers

37. TEM and SEM