Chapter 3: Observing Microorganisms Through a Microscope

Resolution

is the ability of the lenses to distinguish fine detail and structure.

Acid fast stain

binds strongly only to bacteria that have a waxy material in their cell walls.

condenser

A(n) is the lens that directs the light rays through the specimen.

endoscope

A(n) is a special resistant, dormant structure formed within a cell that protects a bacterium from adverse environmental conditions.

foreign substance

Antibodies are natural defense molecules that are produced by humans and many animals in reaction to a(n) , or antigen.

gelatinous covering

Many microorganisms contain a(n) called a capsule.

Special stains

are used to color parts of microorganisms.

colorless bacteria

Preparing against a colored background is called negative staining.

biological specimen

A mordant would increase the affinity of a stain for a(n) .

alcohol solution

A simple stain is an aqueous or of a single basic dye.

prefix micro

The indicates the unit following it should be divided by 1 million.

light rays

When pass through the two materials, the rays change direction from a straight path by bending or changing angle at the boundary between the materials.

darkfield microscope

A(n) is used to examine live microorganisms that either are invisible in the ordinary light microscope, can not be stained by standard methods, or are so distorted by staining that their characteristics are obscured.

objective lenses

The are the lenses closest to the specimen.

refractive index

The is a measure of the light- bending ability of a medium.

beam of electrons

The passes through the specimen and then through an electromagnetic objective lens, high magnifying the image.

Phase contrast microscopy

is useful because the internal structures of a cell become more sharply defined, permitting detailed examination of living microorganisms.

Confocal microscopy

is a technique in light microscopy used to reconstruct three- dimensional images.

electromagnetic projector

The electrons are focused by a(n) lens onto a viewing screen and saved as a digital image.

ocular lens

The is the eyepiece.

Differential interference contrast microscopy

uses differences in refractive indexes.

color of basic dyes

The is in cation.

Differential stains

react differently with different kinds of bacteria and can be used to distinguish them.

electron microscope

The scanning overcomes the sectioning problems associated with a transmission .

Differential interference contrast microscopy

has prisms that split each light beam, adding contrasting colors to the specimen.

Differential interference contrast microscopy

uses two beams of light.