Microbiology Lab Exam 1

Parfocal

the ability of a microscope ® to remain in focus when changing from one objective lens to another with little or no adjustment

Arm

connects base to body tube that contains lenses

Base

where the light source, on/off switch & rheostat are located

Ocular lenses

eyepieces/ 10x magnification

Revolving nose piece

holds objective lenses

Coarse adjustment knob

large knob on either side of arm that moves stage up or down rapidly to focus specimen

Fine adjustment knob

small knob in center of coarse adjustment knob that moves stage up or down slightly to adjust sharpness of specimen in focus

Stage

platform that holds specimen

condensor

directs & condenses rays from light source at base, can be moved up or down by knob on right side of arm below focus knobs

diaphragm

Regulates the amount of light on the specimen

blue filter

blue glass in filter

total magnification

ocular lens x objective lens

resolution

the ability of a microscope to separate or distinguish between small objects that are close together

4 ways to optimize resolution

1. raise condenser

2. open diaphragm

3. use blue filter

4. use immersion oil with 100x

ubiquity

the state or capacity of being everywhere

Characteristics of bacterium

1. Unicellular

2. Prokaryotic

3. surrounded by a cell wall of peptidoglycan

Bacteria growth on solid media

growth is visible; discrete colonies

Bacteria growth on liquid media

growth will cause broth to become turbid

Characteristics of fungi

1. Eukaryotic cells

2. belong to the kingdom of mycetae

3. non-photosynthetic

4. cell wall composed of chitin

Molds

filamentous growths gives a fuzzy appearance

Hyphae

filaments with terminal spores

Septate hyphae

have cross walls

Non-septate hyphae

no cross walls

Mycelium

a mass of hyphae that intertwines into a mat of growth

Sporangiospores

asexual spores encased in membranous sac called a sporangium

Conidia

asexual spore not enclosed in a sac

Rhizopus

has long non-septate hyphae with sporangiospores and root-like hyphae called conidia

Rhizopus

Aspergillus

1. has septate hyphae with conidia

2. mycelial growth is black

Aspergillus

Penicillium

1. has septate hyphae with conidia

2. mycelial growth is blue-green

Penicillium

Yeasts

fungi that do not form hyphae

How does yeast reproduce?

budding

Saccharomyces cerevisiae

common yeast

Pseudohyphae

chains of budding cells that are attached to parent cell

Dimorphic fungi

can be yeast or a mold

Aseptic technique

manipulation of microbial microorganisms where there is no contamination

slant

bacteria growth will appear as a colony or film

pure culture

contains only a single kind of organism

Broth culture

several loops of culture to slide

Solid culture (slant/plate)

1. 2-3 drops of water

2. transfer small amount of cells to water

purposes of heat fixing

1. bacteria on the slide will be killed by the heat

2. cells will be "fixed" by the heat, they cannot be washed off when applying stain

Characteristics of a good smear

1. Smear is not to thick

2. cells are adhered to the slide via heat fixing

3. represents accurate size and shape of cells

simple staining

a method of staining microorganisms with just a single stain

Rod (bacilli)

Spherical (cocci)

Spiral (curved rods)

basic stains - positively charged

1. Methylene blue

2. Crystal violet

3. Safranin

4. Basic fuchsin

Acidic dyes - negatively charged

the background is colored while the cells are colorless

Metachromatic granules

distinct reddish-purple granules within cells that show up when the organisms are stained with methylene blue

Pleomorphism

demonstrates several different cell shapes

differenital stain

distinguish between different bacterium based on different dyes

Gram-positive

1. will show up purple at the end

2. thick layer of peptidoglycan

Gram-negative

1. will show up pink at end of staining

2. thin layer of peptidoglycan

primary stain

crystal violet: both cells are stained

Mordant

Gram's iodine: forms insoluble complex on gram-positive; both cells are purple

Decolorizing agent

ethanol: gram-negative cells become colorless

Counterstain

Safranin: turns gram-negative pink

aerobe

utilizes oxygen

microaerophilic

need oxygen in lower-than-atmospheric conditions

anaerobic

absence of oxygen

anaerobic respiration

carry out fermentation

Aerotolerant

can grow in oxygen; do not use oxygen in metabolism

facultative anaerobes

grow better with oxygen; can grow without it

Fluid thioglycolate medium (FTM)

viscous liquid (semi-solid) that contains a reducing agent (sodium thioglycolate) that will tie up oxygen to create an anaerobic environment in the lower portion of the tube

obligate aerobes

grow near the surface where oxygen is

obligate anaerobes

only grow below the surface where there is no oxygen

facultative anaerobes

grow throughout medium

psychrophile

temp between -5 C and 20 C

mesophile

temp between 20 C and 40 C

thermophile

temp between 5 C and 80 C

hyperthermophiles

grow above 80 C

2 effects of temperature variation

growth and pigment production

hypertonic

solute concentration is greater on the outside; cell shrinks

isotonic

solute concentrations are the same

hypotonic

solute concentration is lower on the outside of cell; cell swells

halophile

require high salt conc. to grow

halotolerant

capable of growing in moderately high salt conc.

osmophile

grow in conc. of high sugars

pyrimidine dimers

form when DNA is exposed to UV light

Kirby-Bauer method

tests sensitivity of bacteria to antimicrobials

zone of inhibitation

1. clear area around the disk that forms

2. measure diameter

Mueller-Hinton II agar

media used for Kirby-Bauer method

antiseptics

chemical solutions that kills microorganisms on tissues

disinfectant

chemical solution that kills microorganisms on surfaces

filter paper disk diffusion

used to test the effectiveness of antiseptics and disinfectants

characteristics of molds

1. multicellular

2. hyphae

3. spores

characteristics of yeast

1. unicellular

2. pseudohyphae

3. budding

saccharomyces

Escherichia coli

negative rods

facultative

white

Micrococcus luteus

positive cocci that occur in pairs

Aerobes

yellow

Serratia marcescens

negative rods

mesophile

red

Staphylococcus aureus

positive cocci, irregular clusters

halotolerant

Clostridium sporogenes

positive rod

anaerobe

Bacillus megatarium

positive rod

aerobe

Pseudomonas aeruginosa

negative rods

obligate aerobe

Geobacillus stearothermophilus

gram-positive rids

thermophile

Pseausomonas fluorescens

negative rods

psychrophiles

Saccharomyces cerevisiae

yeast