Microscopy Review

Number of mm in a meter

1,000

Number of mcm (micrometers, um) in a mm

1,000

Number of nanometers (nm) in a micrometer

1,000

Amoeba

Common in freshwater, have pseudopods, protozoa, 500mcm

Paramecium

Common in freshwater, have cilia, protozoa, 250 mcm

Diatoms

Marine with silicon shells, important plankton, algae, 200 mcm

Euglena

Common in freshwater, have flagella and chloroplasts, protozoa, 130 mcm

Yeast

Fungi, 10 mcm, makes dough rise

E. Coli

Helps in digestion, one form causes severe food poisoning, bacteria, 2mcm

Lactobacillus

Used to make yogurt, aids in digestion, bacteria, 2 mcm

Cyanobacteria

Has chlorophyll, carries out photosynthesis, bacteria, 1 mcm

Staphylococcus

Causes staph infections, bacteria, 1 mcm

Small Pox Virus

Causes small pox, virus, 0.3 mcm

Rabies Virus

Causes rabies, virus, 0.15 mcm

Influenza Virus

Causes the flu, virus, 0.1 mcm

Polio Virus

Causes polio, virus, 0.03 mcm

Rinovirus

Causes common cold, virus, 0.03 mcm

Bright Field Microscope

Most widely used; image formed when light is transmitted through the specimen, specimen produces an image darker than surrounding illuminated field, can be used with live, unstained, and preserved or stained specimens; uses visible light as illumination source; up to 2000 X

Dark Field Microscopy

Created by adding a stop to the condenser of a bright-field microscope; stop blocks all light from entering objective lens except for peripheral light; specimen produces image brightly illuminated against dark field; uses visible light as illumination source; up to 2000 X

Dark Field Microscopy

Effective for visualizing living cells that would be distorted by drying or heating or that can’t be stained with usual methods; does not allow for visualization of fine internal details of cell; uses visible light as illumination source; up to 2000 X

Phase Contrast Microscope

Used for live specimens, specimen is contrasted against a gray background; good for internal cell details; uses visible light as illumination source; up to 2000 X

Differential-Interference Microscope

Allows for detailed view of live, unstained specimens; includes 2 prisms that add contrasting colors to image; image is colorful and 3-D; uses visible light as illumination source; up to 2000 X

Fluorescence Microscope

Includes UV radiation source and filter that protects viewer’s eyes; used with dyes that show fluorescence under UV rays; forms color image against black field; used in diagnosing infections caused by specific microbes using fluorescent antibodies; up to 2000 X

Confocal Microscope

Allows for viewing cells at higher magnifications using a laser beam of light to scan various depths in the specimen; uses UV rays; up to 2000 X; most often used on fluorescently stained specimens

Electron Beam Microscopes

Biologists began using in early 1930s; originally for non-biological materials, forms image w/ beam of electrons; e- travel in wavelike patters 1,000 shorter than visible light waves, increases resolving power; magnification can be very high (5,000 x - 1,000,000 for biological specimens)

Transmission Electron Microscope

Often used to view structures of cells and viruses; electrons transmitted through the specimen; specimen must be very thin (20-100 nm thick) and stained to increase image contrast; dark areas represent thicker or deeper parts

Scanning Electron Microscope

Creates detailed 3-D image of all kinds of objects; e- bombard surface of whole metal-coated specimen; e- deflected from surface are picked up by detector; e- pattern displayed as an image on tech screen; contours of specimens are very revealing; color can be added by computer

Ocular

Part of microscope: magnifies image formed by objective

Nosepiece

Part of microscope; holds the objective

Objectives

Part of microscope; lenses that receive the light from the field of view and form the first image

Stage

Part of microscope; supports the slide and the specimen

Stage Clips

Part of microscope; holds the slide in place

Base

Part of microscope; foundation which supports the scope and keeps it stable

Diaphragm

Part of microscope; controls the amount of light reaching the specimen

Illuminator

Part of microscope; source of light

Course Adjustment

Part of microscope; used for initial or low power adjustment

Fine adjustment

Part of microscope; used for fine tuning and high power focusing

Arm

Part of microscope; supports the ocular, objectives, and body tube

Body Tube

Part of microscope; tube or barrel between ocular and objectives

Inverted and reversed

How do objects appear in microscopy?

T

T or F: only a thin layer of the specimen is in focus at any level

T

T or F: Actual movement is opposite to appeared direction of movement (in microscopy)

Ocular magnification * objective magnification

How do you find total magnification?

10x or 12x

What are the two most common ocular magnifications?

4x, 5x, 6x

3 Most common scanning power magnifications (objectives)

10x or 12x

2 most common low power magnifications (objectives)

40x, 43x, 45x

3 most common high power magnifications (objectives)

low power to high power

What change in objectives will cause the following: darker field of view, decreased viewing field size, increased image size, increased resolution, decreased working distance, reduced depth of focus?