question

microscope base

answer

bottom of the microscope

question

microscope arm

answer

with the base, used to carry the microscope

question

microscope stage

answer

holds the slide

question

microscope body tube

answer

transmit the magnified image

question

microscope condenser

answer

lenses that focus light into a cone

question

microscope iris diaphragm

answer

controls the angle and size of the cone of light

question

microscope revolving nosepiece

answer

holds objective lenses

question

microscope obective lenses

answer

magnify & invert the image

question

microscope focal point

answer

formed when light rays converge at one point

question

microscope coarse adjustment

answer

larger knob used to focus on low power

question

microscope fine adjustment

answer

smaller knob used to focus with high power and oil immersion

question

microscope field of vision

answer

area seen through the microscope

question

microscope magnification

answer

the number of times an image is increased in size

question

formula for magnification

answer

determined by multiplying the power of the objective by the power of the ocular lens

question

resolution

answer

ability to distinguish two points as distinct and separate

question

refractive index

answer

the amount light bends when it enters a new medium

question

parfocal

answer

when one lens is focused, all the other lenses will also be in focus

question

which lens has the shortest focal distance?

answer

oil immersion

question

the three basic bacterial shapes

answer

rods (bacilli), spheres (cocci), spirals

question

the field of vision decreases when the magnification...

answer

increases

question

why does immersion oil increase resolution?

answer

it has the same refractive index as glass (1.52) and the light does not bend between the slide and the objective lens

question

when viewing large organisms like fungi or protozoa, it is best to use the ___________ lens

answer

low power

question

spherical aberration

answer

when the middle of the field of view is in focus but the periphery is blurry. Light passing through the middle of the lens has a different focal point than light passing through the outside

question

chromatic aberration

answer

many colors appear in the field. occurs when each wavelength of light has a different focal point

question

In bright field microscopy, the image is made from:

answer

light that is transmitted through a specimen

question

Bacterial stains will _____ the organism

answer

kill

question

The condenser lens ___________ the light

answer

concentrates

question

Refraction is ________ of light rays

answer

bending

question

A microscope produces 2 images.
One is _____ and one is ______.

answer

real
virtual

question

The virtual image appears ___________ the microscope

answer

below or within

question

The formula for calculating magnification:

answer

total magnification =

magnification by the objective lens
x
magnification by the ocular lens

question

Resolution is defined as:

answer

clarity of an image

question

The limit of resolution is:

answer

an actual measurement of how far apart two points must be for the microscope to view them as being separate

question

Write the formula for the limit of resolution:

answer

λ
D=-----------------------------------
NAcondenser +NAobjective

question

Numerical Aperture is:

answer

a measure of a lens's ability to "capture" light coming from the specimin and use it to make the image

question

Using immersion oil makes the numerical aperture__________

answer

increase

question

In dark-field microscopy, objects appear ________;
against a _________ background;

answer

brightly lit
dark

question

In phase contrast microscopy, the specimen appears as various levels of ______ against a bright background

answer

"darks"

question

Fluorescent microscopy uses fluorescent ______
that emit light when illuminated with
_____________ light

answer

dye
ultraviolet
;

question

A mixed culture contains:

answer

two or more species

question

A pure culture contains:

answer

only a single species

question

The purpose of streaking bacteria on a plate is to:

answer

isolate an individual species from a mixed sample

question

Individual cells grow into:

answer

colonies

question

CFU stands for:

answer

colony-forming unit

question

A CFU consists of:

answer

individual cells or pairs, chains, or clusters of cells

question

Ubiquitous:

answer

Organism can be found everywhere, could be isolated from soil, water, plants, and animals

question

Define pathogenic:

answer

capable of causing disease

question

Define opportunistic pathogen

answer

capable of causing disease if introduced into a suitable part of the body

question

define reservoir:

answer

any area where a microbe resides and serves as a potential source of infection

question

Pellicle

answer

organisms float on top and produce a surface membrane

question

sediment

answer

organisms sink to bottom

question

turbidity

answer

evenly distributed throughout

question

flocculent

answer

suspended chunks

question

Organisms that can infect us:

answer

Amoeba (Entamoeba histolytica causes dysnetery)
Nematodes
(Enterobius vermicularis - pinworm - intestines
Ascaris lumbricoides - intestines
Necator americanus - intestines
Trichinella spirallis - muscles)
Ciliates (Balantidium coli - intestines)
;

question

Organisms that may transmit disease

answer

arthropods

question

most commonly used staining method

answer

gram staining

question

gram staining - which stain is applied first?

answer

crystal violet

question

gram staining
;
what forms inside the cell after you add iodine?
;
;

answer

crystal violet-iodine complex

question

gram staining
;
what type of cell is decolorized?

answer

gram negative

question

gram staining
;
Name the counterstain

answer

safranin

question

what effect does alcohol have on the gram-negative cell wall?

answer

the alcohol extracts the lipid, making the gram negative cell wall more porus and unable to retain the crystal-iodine complex, decolorizing it

question

Explain why gram-positive cells are not decolorized

answer

the thicker peptidoglycan traps the crystal violet-iodine complex more effectively, making them less susceptible to decolorization

question

What color will gram-positive cells be if the decolorizer is left on too long?

answer

reddish

question

Describe the appearance of a good emulsion

answer

dries to a faint haze on the slide

question

what happens to older gram-positive cultures?

answer

may decolorize and give a gram negative result

question

In the negative staining technique a chromogen (dye) has a ____________ charge.

answer

negative

question

The pH of negative stains is_____________

answer

acidic

question

Negative stains do not enter bacterial cells because the charges ____________ each other.

answer

repel

question

Negative staining is commonly employed for bacteria that are:

answer

too delicate to withstand heat-fixing

question

Acid-fast bacteria have ____________ in their cell walls

answer

mycolic acid

question

Acid-fast organisms resist _________ by _________ alcohol.

answer

decolorization, acid

question

The names of the 2 acid-fast staining procedures are:

answer

Ziehl-Neelsen (ZN)
Kinyoun (K)

question

When preparing an acid-fast smear, a drop of __________ is used to help the ____________ organisms adhere to the slide

answer

serum, slippery

question

The primary stain in the ZN method is _________ because it is soluble in _____________

answer

carbolfuchsin, lipid

question

Heating causes acid-fast cell walls to _________

answer

melt

question

the counterstain in an acid-fast stain is

answer

methylene blue

question

Acid fast cells are colored

answer

reddish purple

question

Non acid-fast cells are

answer

blue

question

Capsules are made of __________ or _________

answer

mucoid polysaccharides, polypeptides

question

(Capsule stain) Two examples of netgaive stains are:

answer

Congo red, nigrosin

question

(Capsule stain) Negative stain pH is ___________ and they stain the background

answer

acidic

question

(Capsule stain) A basic stain is used to stain _________

answer

the cell

question

(Capsule stain) We do not heat fix because:

answer

it causes the cells to shrink, leaving an artifactual white halo that may be interpreted as a capsure

question

Cells stick to the slide by adding a drop of ___________

answer

serum

question

An endospore is:

answer

A dormant form of the bacteria that allows it to survive poor environmental conditions

question

Endospores are covered with a protein called:

answer

keratin

question

(endospore stain) The primary stain is called:

answer

malachite green

question

(endospore stain) The decolorizer is:

answer

water

question

(endospore stain) The cells that are counterstained with safranin are ______________ and _____________

answer

vegetative cells, spore mother cells

question

Location of endospore: central

answer

In the middle of the cell

question

Location of endospore: terminal

answer

at the end of the cell

question

location of endospore: subterminal

answer

between the end and the middle

question

Two spore shapres are:

answer

spherical, elliptical (oval)

question

some spores are large and make the cell look:

answer

swollen

question

Why can't we view flagella using an unstained preperation?

answer

flagella are too thin to be observed with light microscope and ordinary stains

question

flagella - monotrichous

answer

one flagellum at one end

question

flagella - amphitrichous

answer

flagella at both ends

question

lophotrichous

answer

tufts of flagella at one end

question

peritrichous

answer

flagella all over the cell

question

Why does light of a shorter wavelength produce a clearer image than light of longer wavelengths?

answer

As wavelength gets smaller, resolution gets smaller because wavelength is on the top of the equation

question

Colony morphology includes:

answer

colony size, color, shape, margin, elevation, texture

question

colony morphology - shape

answer

round, irregular, punctiform

question

colony morphology - margin

answer

entire, undulate, lobate, filmentous, rhizoid

question

colony morphology - elevation

answer

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

question

colony morphology - texture

answer

moist, mucoid, dry

question

colony morphology - color

answer

opaque, translucent, shiny, dull

question

colony morphology - other factors

answer

length of incubation, temperature of incubation, type of medium grown on, oxygen concentration during incubation

question

Why are microorganisms located on the desks not sterilized as extremely as the plates?

answer

Bugs that grow on desks at 25 degree C are probably not human pathogens. Plates have many more bugs on them as well.

question

What is significant about organisms that grow well at 37 degrees C?

answer

They probably came from humans.

question

Capsule stain - why must the sample be emulsified in serum?

answer

To help them stick to the slide because they are slippery.

question

Why do oral bacteria produce a capsule?

answer

protection against phagocytocis and to stick to surfaces and each other forming a biofilm

question

Why was an older culture of Bacillus used to demonstrate endospores?

answer

Spores are formed in response to nutrient depletion, so the

question

Why can't flagella be observed in action?

answer

Because they are too thin to be seen with regular stain. A mordant must be used to encrust the flagella so it is thick enough to be seen.

question

Type of microscopy:
[image]

answer

bright field microscopy

question

Type of microscopy:
;
[image]

answer

dark field microscopy

question

type of microscopy:
[image]

answer

fluorescence microscopy

question

type of microscopy:
;
[image]

answer

phase contrast microscopy

question

bacterial morphology:
;
[image]

answer

gram positive cocci

question

bacterial morphology
;
[image]

answer

ovoid coccus (Lactococcus lactis)

question

bacterial morphology
;
[image]

answer

gram positive bacilli (Bacillus)

question

bacterial morphology
;
[image]

answer

gram positive staphylococci

question

bacterial morphology:
[image]

answer

gram positive streptobaccillus

question

bacterial morphology:
[image]

answer

gram positive spirilla

question

bacterial morphology:
[image]

answer

spirochetes

question

bacterial morphology:
[image]

answer

gram negative vibrio (Vibrio cholera)

question

bacterial morphology:
[image]

answer

gram negative diplococci (Nesseria gonorrhea)

question

bacterial morphology:
[image]

answer

tetrads (Micrococcus roseus)

question

bacterial morphology:
[image]

answer

gram positive streptococci
(Streptococcus pyogenes)

question

bacterial morphology
[image]

answer

gram positive bacilli, palisades arrangement
(Corynebacterium)

question

How to do a plate streak:

answer

[image]

question

Broth growth:
;
[image]
;

answer

1- obligate aerobes (need oxygen) - growth at top
2 - faculative anaerobes - growth throughout, but more growth at top
3- microaerophiles
4 - anaerobes - growth at bottom, no growth at top where oxygen is present

question

Gram stain procedure

answer

1 - heat fix emulsion
2 - cover smear with crystal violet stain for 30-60 sec
3 - rinse with distilled water
4 - cover smear with iodine for 30 - 60 sec
5 - rinse with distilled water
6 - decolorize with alcohol
7 - counterstain with safranin for 30 - 60 sec
8 - rinse with distilled water
9 - blot dry with bibulous paper

question

gram positive vs gram negative results:
[image]

answer

gram positive - dark purple
gram negative - pinkish red

question

Negative stain:
[image]

answer

Bacteria are unstained against dark background

question

acid-fast stain (ZN)
[image]

answer

in ZN stain, acid fast cells are reddish-purple (non acid fast cells are blue)

question

acid fast stain (K)
[image]

answer

acid fast cells are reddish purple (non acid fast cells are blue)

question

capsule stain:
[image]

answer

acidic stain colorizes the background while the basic stain colorizes the cell, leaving the capsules as unstained white clearings around the cell

question

Flagella stain:
[image]

answer

peritrichous flagella

question

flagella:
[image]

answer

monotrichous

question

flagella:
[image]

answer

amphitrichous

question

flagella:
[image]

answer

lophotrichous

question

Endospores:
[image]

answer

terminal swollen

question

endospores
[image]

answer

central

SCCC Microbiology Lab 1 – Flashcards

Unlock all answers in this set

Haven't found what you were looking for?

Search for samples, answers to your questions and flashcards