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culture

a medium that contains living microbes

pure culture

a culture that contains a single species

aseptic

transfer of microbes from their pure culture to a sterile medium without contamination of yourself, the environment, the source culture, or the medium being inoculated

safety practices for aseptic transfers

1) minimize the potential of contamination
2) be organized
3) place all media tubes in a test tube rack when not in use whether they are sterile or not
4) take your time
5) never hold a tube culture by it's cap
6) hold the inoculating loop or needle in your hand like a pencil in your dominate hand
7) adjust your bunsen burner so your flame has an inner and outer cone

broths

used to grow microbes when fresh cultures or large numbers of cells are required

agar slants

generally used to grow stock cultures that can be refrigerated after incubation and maintained for several weeks

plated media

typically used for obtaining isolation of species, differential testing, and quantifying bacterial densities

instruments used for transfers

inoculating loops or needles

mixed culture

a microbial culture consisting of two or more species

commonly used isolation technique

streak plate

colony-forming unit

term used to define a cell or a group of cells that grows into a colony

the basic categories of colony morphology

shape, margin (edge), elevation, texture, and color

colony shape can be described as :

circular, irregular, or punctiform (tiny)

colony margin may be described as:

entire (smooth with no irregularities), undulated (wavy), lobate (lobed), filamentous, or rhizoid (branched like roots)

colony elevations can be described as:

flat, raised, convex, pulvinate (very convex), and umbonate (raised in the center)

colony texture can be described as:

moist, mucoid, or dry

colony pigment production can be described as:

color, opaque, translucent, shiny, or dull

filiform growth

dense and opaque with a smooth edge

friable

crusty

Most species in the genus Mycobacterium produce ___ growth.

friable

2 important factors influencing bacterial growth

incubation time and temperature

What organisms were used in the colony morphology experiment?

Micrococcus luteus
Mycobacterium smegmatis
Corynebacterium xerosis
Proteus mirabilis
Bacillus subtilis
Lactobacillus plantarum

Why are growth characteristics more useful on agar plates than on agar slants?

the plates have a larger surface area for streaking to isolate

Why are agar slants better suited than agar plates to maintain stock cultures?

Slants are better suited because they can be capped, preventing the agar and culture from drying out. The cap also prevents airborne contaminates from entering the slant. Slants take up less storage space.

pigmented

produces colored growth

spreading edge

solid growth seeming to radiate outward

pellicle

surface membrane caused by organisms floating on top of the medium

sediment

organisms that sink to the bottom of the medium

inoculation

introduction of a small sample of inoculum into a container of media to produce a culture of observable growth

The 5 I's of culturing microbes

inoculation
incubation
isolation
inspection
identification

progenitor

termed a colony forming unit

2 common isolation techniques

streak plates
pour plates

incubation

temp-controlled chamber
microbe multiplies and produces macroscopically observable growth

isolation

seperating an individual bacterial cell from other cells

colony

consists of one species in a mound of cells formed from a colony formig unit

colony indicator is dependent on :

media, temp, time incubated

inspection

observation both macroscopic and microscopic appearance, biochemical tests, genetic characteristics, immunological testing

mixed culture

hold two or more identified species or organisms

contaminated culture

a once pure or mixed culture that has unwanted microbes growing

vortex mixer

small machine that mixes test tubes with broth and microbes in it

a nanometer is ____ of a meter

one billionth
(0.000000001 m)

a micrometer is ____ of a meter

one millionth
(0.000001 m)

wavelength

distance between 2 corresponding parts of a wave

wave of 400 nm

violet

wave of 650 nm

red

white light is composed of ____

many colors and an average of 550 nm

magnification results when ___

a beam of radiation refracts (bends) as it passes through a lens

curved glass refrects ___

light

magnetic fields refract ___

electron beams

Why does a lens refract light?

the lens is optically dense compared to the surrounding medium (light travels more slowly through the lens than through air)

phase

all the wave's crests and troughs are aligned - can enhance contrast

wavelength of radiation

distance between two corresponding parts of a wave

magnification

results when a beam of radiation refracts as it passes through a lens

resolution

aka resolving power - the ability to distinguish objects that are closer together

contrast

differences in intensity between two objects or between an object and its background - important in determining resolution

visible light is made up of __-

a narrow band of wavelengths of radiation

What kind of lights ae used in microscopy?

visible and ultraviolet

A lens refracts light waves that pass through its ___ more than light rays that pass through its ___.

periphery, center

What happens to light rays as they travel past the focal point?

they spread apart and produce an enlarged, inverted image

empty magnification

image is blurry and faint

Todays microscopes can distinguish objects as close together as ___.

0.2 micrometers

magnification occurs in two phases

real image, virtual image

What forms the real image?

the objective lens

What forms the virtual image?

the real image is projected to the ocular where it is magnified again

total magnification

magnification of the final image is a product of the seperate magnifying powers of the objective lens and the ocular
(power of objective times power of the ocular

visible light wavelength is

400 nm- 750 nm

numerical aperture of lens is ____

from 0.1 to 1.25

oil immersion lens

requires the use of oil to prevent the refraction of light

shorter wavelength and larger numerical aperture will provide _____.

better resolution

What is the resolution of the oil immersion lens?

0.2 micrometer

what is numerical aperture?

the ability of a lens to gather light from a specimen and use it to make the image

What is the most common light microscope?

bright field microscope

With a bright field microscope, what is illuminated?

the background (field)

contrast

differences in intensity between two objects, or between an object and the background

What is contrast important in determining?

resolution

What can increase contrast?

staining and the use of light that is in phase

What does the condensor lens do?

directs light through the specimen as well as one or more mirrors or prisms that deflect the path of the light rays from an objective lens to the ocular lens

What are the 2 types of bright field microscopes?

simple and compound

Simple Bright-field microscope

has a single magnifying lens, is similiar to a magnifying glass, capable of 300x magnification

Compound Bright-light microscope

has a series of lenses for magnification
light passes through specimen into objective lens
oil immersion lens increases resolution
have one or two ocular lenses
most have a condenser lens

What is the limit of useful magnification for light microscopes? Why?

2000x because their resolution is restricted by the wavelength of visible light

magnification of scanning lens

4X

magnification of low-power objective lens

10X

magnification of high power lens

40X

magnification of oil immersion lens

100X

magnification of ocular lens

10X

ocular lens

remagnifies the image formed by the objective lens

body

transmits the image from the objective lens to the ocular lens using prisms

objective lens

primary lenses that magnify the object

stage

holds the microscope slide in place

condensor

focuses light through the specimen

diaphragm

controls the amount of light entering the condenser

illuminator

light source

coarse focusing knob

moves the stage up and down to focus the image

How do you carry a microscope?

with one hand on the arm and the other beneath the base

How do you store a microscope?

with the short objective lens in place, lower the stage, turn light intensity to minimum and turn it off, clean the lenses, wrap the cord correctly and cover

How do you clean the lenses?

-clean the condenser and objective lenses with lens paper or cotton swabs and a 95% ethanol cleaning solution
-clean the ocular lens with a cotton swab moistened with 95% ethanol cleaning solution

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