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?

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 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

Stained Bacteria

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