Chapter 2 - How we See the Invisible World Flashcards
What are the 5 I’s of Culturing Microbes
- Inoculation
- Isolation
- Incubation
- Inspection
- Identification
If an individual bacterial cell is separated from other cells and has space on a nutrient surface, it will grow into a mound of cells called:
A colony
A colony consists of ___ species
One
There are _____ isolation techniques
Three
Media can be classified according to what three properties
- Physical state
- Chemical composition
- Functional type
Broth; does not solidify
Liquid
Contains solidifying agent (agar or gelatin)
Semisolid
Firm surface for colony formation
- Contains solidifying agent
- Liquefiable and nonliquefiable
Solid
What are the chemical contents of media?
- Synthetic
- Complex or nonsynthetic
- General purpose media
- Enriched media
Media for special microbial groups:
- Selective media
- Differential media
Temperature-controlled chamber
Incubation
Observation; macroscopic and microscopic
- Pure culture
- Mixed cultures
- Contaminated culture
Inspection
Macroscopic and microscopic appearance, biochemical tests, genetic characteristics, immunological testing
Identification
Potentially hazardous cultures and specimens are usually disposed of in what two ways
- Steam sterilization
2. Incineration
Key characteristics of a reliable microscope are:
- Magnification
- Resolving power
__________ occurs when light passes from one medium, such as air, to another, such as glass, changing the direction of the light rays.
Refraction
Light rays passing from one medium to another may be either _________ or _________
Refracted or reflected
Occurs when light passes from one medium, such as air, to another, such as glass, changing the direction of the light rays
Refaction
When light passes through a convex lens, it is refracted ______ a focal point on the other side of the lens
Toward
The _____ ______ is the distance to the focal point
Focal length
Light passing through a concave lens is refracted ____ from a focal point in front of the lens
Away
Magnification in most microscopes results from interaction between;
Visible light waves and curvature of the lens
Angle of light passing through convex surface of glass changes
Refraction
Depending on the size and curvature of the lens, the image appears ________
Enlarged
Extent of enlargement
Magnification
Magnification occurs in what two phases?
- The objective lens forms the magnified . real image
- The real image is projected to the ocular where it is magnified again to form the virtual image
The objective lens forms the magnified ____ _____
Real image
The real image is projected to the ______ where it is magnified again to form the _______ _____
Ocular
Virtual image
A product of the separate magnifying powers of the two lenses
Total magnification
Power of objective x power of ocular =
Total magnification
Defines the capacity to distinguish or separate two adjacent objects
Resolution
Resolution defines the capacity to distinguish or separate two adjacent objects. What is this called?
Resolving power
What is the visible light wavelength?
400 nm-750 nm
_________ ________ of lens ranges from 0.1 to 1.25
Numerical aperture
Requires the use of oil to prevent refractive loss of light
Oil immersion lens
_______ wavelength and ______ numerical aperture will provide better resolution
Shorter wavelength and larger
What is the oil immersion objectives resolution?
0.2 μm
What are the variations on the optical microscope?
- Bright-field
- Dark-field
- Phase-contrast
The differential interference contrast microscope is similar to the phase contrast but has more ___________
Refinements
- Modified compound microscope with an ultraviolet radiation source and filter that protects the viewer’s eye
- Uses dyes that emit visible light when bombarded with shorter UV rays - fluorescence
- Useful in diagnosing infections
Fluorescence microscope
Forms an image with a beam of electrons that can be made to travel in wavelike patterns when accelerated to high speeds
Electron microscope
Electron waves are ______ times shorter than the waves of visible light
100,000
Electrons have tremendous power to resolve minute structures because resolving power is a function of __________
Wavelength
Oil immersion magnification is between:
40X and 2000X
Electron microscope magnification is between:
5,000X and 1,000,000X
Transmit electrons through the specimen. Darker areas represent thicker, denser parts and lighter areas indicate more transparent, less dense parts
Transmission electron microscopes (TEM)
Provide detailed three-dimensional view. Bombards surface of a whole, metal-coated specimen with electrons while scanning back and forth over it
Scanning electron microscopes (SEM)
Preparation of a slide depends on:
- Condition of specimen
- Aims of examiner
- Type of microscopy available
Allow examination of characteristics of live cells: size, motility, shape, and arrangement
Wet mounts and hanging drop mounts
Made by drying and heating a film of specimen. This smear is stained using dyes to permit visualization of cells or cell parts
Fixed mounts
Dyes create contrast by imparting a color to ____ or ____ _____
Cells or cell parts
What are the two types of dyes?
- Basic dyes
2. Acidic dyes
What are the two types of stains?
- Positive staining
1. Negative staining
What are the three types of staining?
- Simple stains
- Differential stains
- Structural
