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Questions and Answers
What is the resolving power of the unaided human eye approximately?
What is the resolving power of the unaided human eye approximately?
- 0.1 mm
- 0.2 mm (correct)
- 0.3 mm
- 0.4 mm
What type of microscopes are used to observe unstained living microorganisms?
What type of microscopes are used to observe unstained living microorganisms?
- Phase-contrast microscopes (correct)
- Electron microscopes
- Simple microscopes
- Fluorescence microscopes
What is the purpose of the UV light source in fluorescence microscopes?
What is the purpose of the UV light source in fluorescence microscopes?
- To cause certain dyes and pigments to emit a longer-wavelength light (correct)
- To kill microorganisms
- To observe unstained living microorganisms
- To magnify microorganisms
What is the limitation of using electron microscopes?
What is the limitation of using electron microscopes?
What is a simple microscope?
What is a simple microscope?
What is the function of a magnifying glass?
What is the function of a magnifying glass?
What type of microscopes can observe extremely small microbes such as rabies and smallpox viruses?
What type of microscopes can observe extremely small microbes such as rabies and smallpox viruses?
What happens when UV light strikes certain dyes and pigments in fluorescence microscopes?
What happens when UV light strikes certain dyes and pigments in fluorescence microscopes?
What is the basic unit of length in the metric system?
What is the basic unit of length in the metric system?
What is the total magnification of a microscope with a x10 ocular and a x100 objective?
What is the total magnification of a microscope with a x10 ocular and a x100 objective?
What is the approximate diameter of a typical spherical bacterium (coccus)?
What is the approximate diameter of a typical spherical bacterium (coccus)?
What is the approximate magnification of a compound light microscope?
What is the approximate magnification of a compound light microscope?
Which type of microscope is the most common?
Which type of microscope is the most common?
What is the resolving power of a compound light microscope?
What is the resolving power of a compound light microscope?
What is the purpose of a darkfield condenser in a microscope?
What is the purpose of a darkfield condenser in a microscope?
What is the total magnification of a microscope with a x10 ocular and a x4 objective?
What is the total magnification of a microscope with a x10 ocular and a x4 objective?
How is the total magnification of a compound light microscope calculated?
How is the total magnification of a compound light microscope calculated?
What is the term for photographs taken through the lens system of a compound light microscope?
What is the term for photographs taken through the lens system of a compound light microscope?
What is the equivalent of 1 meter in inches?
What is the equivalent of 1 meter in inches?
What is the purpose of the light source in a compound light microscope?
What is the purpose of the light source in a compound light microscope?
What is the total magnification of a microscope with a x10 ocular and a x40 objective?
What is the total magnification of a microscope with a x10 ocular and a x40 objective?
What is the purpose of the objective lens in a microscope?
What is the purpose of the objective lens in a microscope?
What is the size of a typical rod-shaped bacterium (bacillus)?
What is the size of a typical rod-shaped bacterium (bacillus)?
What is the term for a microscope that uses a special condenser to produce an image with a dark background?
What is the term for a microscope that uses a special condenser to produce an image with a dark background?
Which type of archaea is characterized by its ability to thrive in extremely salty environments?
Which type of archaea is characterized by its ability to thrive in extremely salty environments?
What is the primary role of methanogens in their environment?
What is the primary role of methanogens in their environment?
Which scientist is credited with the development of the swan neck experiment?
Which scientist is credited with the development of the swan neck experiment?
What is the purpose of the swan neck experiment?
What is the purpose of the swan neck experiment?
Which of the following products is NOT an example of a food requiring microbial participation in the manufacturing process?
Which of the following products is NOT an example of a food requiring microbial participation in the manufacturing process?
What is the common characteristic of extremely thermophilic archaea?
What is the common characteristic of extremely thermophilic archaea?
What is the limitation of the size of objects that can be seen using a microscope?
What is the limitation of the size of objects that can be seen using a microscope?
What is the typical range of sizes of viruses that cause human diseases?
What is the typical range of sizes of viruses that cause human diseases?
What is the purpose of an ocular micrometer in a microscope?
What is the purpose of an ocular micrometer in a microscope?
What is a unique characteristic of Ebola virus?
What is a unique characteristic of Ebola virus?
What type of microscopes use special techniques to enhance the contrast of the object?
What type of microscopes use special techniques to enhance the contrast of the object?
What is the unit of measurement used to express the size of viruses?
What is the unit of measurement used to express the size of viruses?
What is the function of the objective lens in a microscope?
What is the function of the objective lens in a microscope?
What is an example of an optical instrument that is not a microscope?
What is an example of an optical instrument that is not a microscope?
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Study Notes
Archaea
- No cell wall
- Live in extreme environments
- Examples:
- Methanogens: produce methane gas
- Extremely halophilic: salt-loving
- Extremely thermophilic: heat-loving
Microbiology and Parasitology
Products Requiring Microbial Participation
- Foods:
- Acidophilus milk
- Bread
- Butter
- Buttermilk
- Chocolate
- Coffee
- Cottage cheese
- Cream cheese
- Fish sauces
- Green olives
- Kimchi (from cabbage)
- Meat products (e.g., country-cured ham)
Louis Pasteur's Swan Neck Experiment
- Filled a flask with medium, heated it to kill all life, and then drew out the neck of the flask into a long S
- Prevented microorganisms in the air from entering the flask yet allowed air to flow freely
The Microbial World
- Viewing microorganisms using microscopes
Using the Metric System to Express the Sizes of Microbes
- Metric units used to express sizes of microbes
- Basic unit of length is the meter (m), equivalent to 39.4 inches
- Sizes of bacteria and protozoa usually expressed in micrometers (μm)
- 1 μm = one millionth of a meter
- Typical spherical bacterium (coccus) approximately 1 μm in diameter
- Typical rod-shaped bacterium (bacillus) approximately 1 μm wide x 3 μm long
Compound Microscopes
- Contain more than one magnifying lens
- Illuminate samples with visible light
- Also referred to as compound light microscopes
- Magnify objects about 1,000 times
- Resolving power approximately 0.2 μm
- Calculate total magnification by multiplying ocular lens power by objective lens power
Scanner, LPO, HPO, and OIO
- Different types of magnification with corresponding objective lenses
- x10 ocular x x4 objective = x40 total magnification (scanner, red)
- x10 ocular x x10 objective = x100 total magnification (LPO, yellow)
- x10 ocular x x40 objective = x400 total magnification (HPO, blue)
- x10 ocular x x100 objective = x1,000 total magnification (OIO, white)
Photomicrographs
- Photographs taken through the lens system of the compound light microscope
- Objects observed against a bright background or "bright field"
- Compound light microscope sometimes referred to as a brightfield microscope
Darkfield Microscopes
- Use a darkfield condenser
- Illuminated objects seen against a dark background or "dark field"
- Microscope then called a darkfield microscope
Phase-Contrast and Fluorescence Microscopes
- Phase-contrast microscopes used to observe unstained living microorganisms
- Fluorescence microscopes contain a built-in ultraviolet (UV) light source
- UV light strikes certain dyes and pigments, causing them to emit a longer-wavelength light and glow against a dark background
Electron Microscopes
- Enable observation of extremely small microbes like rabies and smallpox viruses
- Living organisms cannot be observed using an electron microscope due to processing procedures that kill the organisms
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