microorganisms what are they? what do they do? what do they look like?
TRANSCRIPT
Microorganisms
What are they?
What do they do?
What do they look like?
Microbiology• Study of microorganisms
– Organisms not visible with naked eye
– Require magnifying glass or microscope
– Includes wide variety of different organisms
Microorganisms are:
• Bacteria• Viruses• Fungi• Protozoa• Animals
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
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
Microscopy: The Instruments
• A simple microscope has only one lens
• This is A. Van Leeuwenhoek’s microscope from the 1600’s
Figure 1.2b
Parts of a typical light microscope
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
Units of Length
• Light microscope can view objects measured in millimeters and micrometers
• Electron microscope can view objects measured in micrometers and nanometers
Bacteria
• Prokaryotic cells– 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
Stained Bacteria
• Average size: 0.2 -1.0 µm 2 - 8 µm• Basic shapes:
Bacterial Morphology
coccibacilli
spirals
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.
Viruses
• Tiny, nonliving particle that enters and then reproduces inside a living cell
• Most are harmful
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
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
Viruses, Bacteria, & Your Health
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
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)
Common Infectious Diseases
• Bacterial–Lyme Disease–Tuberculosis–Tetanus–Strep Throat
• Viral–The cold–The flu–Cold sores–Chicken pox–AIDS
Streptococcal Skin Infection
Anthrax Lesion
Rash From Lyme Disease
• Common Cold & The Flu Virus– Many different strains
• Round virus –Chicken pox:
causes an itchy rash on human skin
• Bullet-shaped–Rabies virus
infects nerve cells in certain animals
Viral Infection – Cold Sores
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
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
Fungi
• Eukaryotic cells• Can be multicellular
molds or unicellular yeasts
Protozoa
• Unicellular eukaryotic organisms
• Show various forms of motility– Flagella– Cilia– Pseudopodia
Animals
• Multicelluar– Worms– Small arthropods
• Serve as vectors for disease transmission
• Ectoparasites– Feed on blood by
biting
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
Measuring Microorganisms
• Microorganisms, because of their small size, require small units of measurement– Micrometer (um) – is 1x10-6 meter or 0.001
mm• Sufficient to measure bacteria, fungi, protozoa
– Nanometer (nm) – is 1X10-9 meter or 0.001um• Sufficient to measure viruses and sub cellular
particles
Units of Length
• Light microscope can view objects measured in millimeters and micrometers
• Electron microscope can view objects measured in micrometers and nanometers
TEM and SEM