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Lab 1 Objectives
Microbiology Laboratory Safety:
Some unique demands will be placed on you regarding safety.
Microbiology requires the use and handling of microorganisms, some of which are
opportunistic pathogens. It is imperative that you learn how to handle cultures
so as not to contaminate lab materials, yourself, or others. Therefore,
learning and practicing aseptic techniques and other special safety procedures
is vital. Be sure you know the common rules or regulations of lab as
discussed at the beginning of your lab manual. Some of these procedures
are highlighted below.
Biosafety Levels:
Based upon the types of microbes used, and their associated
risks of infection, four primary levels of biosafety have been designated.
A laboratory assigned a particular level is expected to implement the Standard
Laboratory Practices recommended for that level. The
guidelines to biosafety are documented in a couple of informative manuals.
One is called
Biosafety in
Microbiological and Biomedical Laboratories. This publication is
provided by the U.S. Department of Health and
Human Services, the Centers for Disease Control and Prevention, and the National
Institutes of Health. The second publication is called
Laboratory Biosafety Manual sponsored by the World Health Organization.
If you wish to view either of these manuals online you may need to download a
.PDF reader to your computer such as the one provided by
Adobe.
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To compare and
contrast the four levels of biosafety, click the biohazard symbol
below. This symbol warns of the presence of potentially infectious
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Lab Precautions:
To alert you of a specific safety hazards or other precautions
involving methods and techniques, the symbol shown below will be used
throughout this web site. Pay close attention to these precautions!
Brightfield Microscopy:
This type of microscopy is routinely used in beginning biology courses,
including microbiology laboratories. The observed specimen is placed on a
stage that lies directly over a condenser. A light source from below is
directed through the condenser to illuminate the specimen. This results in
objects appearing dark in a bright field.
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The compound light
microscope: Microscopes that use two or more lenses to magnify objects are
called compound microscopes. The total
magnification is determined by multiplying the power of the ocular lens by
the power of the objective lens. Use your lab manual as a source of
information to help you to identify the major parts of a microscope and how
these parts function in the operation of this instrument.
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Wet Mount Slides
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Background and Purpose: Wet mount slide preparations are used to view living cells. This procedure
is ideal for evaluating the actual size and shape of cells, as well as their
motility. In contrast, other slide techniques may use heat to prepare
stained specimens. This heat not only kills cells, but may also alter
their natural size and shape.
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General Procedure:
Slides are prepared by transferring a drop of suspended organisms (e.g.,
pond water, bacterial culture) onto the surface of a clean microscope slide. A cover glass
(slip) is then placed over the drop to spread the water suspension into a thin
film. The wet mount slide can then be examined through the microscope by
using the scanning, low, or high power objectives.
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Materials:
Microscope slides, cover glasses (slips), pipettes, forceps, pond
water, slowing-agent (optional)
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The Protozoa,
Algae, Cyanobacteria, and Microscopic Invertebrates
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Protozoa:
These organisms are unicellular or colonial eukaryotes.
Generally, these heterotrophic protists usually possess some means of
movement and are unpigmented. Based largely on their
form of locomotion, these microbes are
divided into four groups: flagellates, amoebae, ciliates,
and apicomplexa.
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Algae:
The algae are photosynthetic protists.
These organisms are unicellular, colonial, or filamentous eukaryotes which have
chloroplasts
containing chlorophyll a and other pigments. Algae are classified into
several groups. The most common algal members include
the euglenoids, the green algae (flagellated,
filamentous,
and nonfilamentous/nonflagellated forms), the fire algae (dinoflagellates), and the
diatoms.
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Cyanobacteria:
Appearing in colors of black, purple, red, and various shades of green, the
cyanobacteria are members of the Domain Bacteria.
Similar to algae, these prokaryotes are photosynthetic by
utilizing chlorophyll a and other pigments.
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Microscopic Invertebrates:
Representing a portion of Kingdom Animalia, the microscopic invertebrates
include a diverse assemblage of multicellular, eukaryotic organisms.
Some of the common members include hydra, flatworms, roundworms,
gastrotrichs, rotifers, oligochaetes, water bears, and
crustaceans.
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For Practice
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