Biol 2051 Lab Midterm

Front 1

complex medium

Back 1

digests of chemically undefined substances such as yeast and meat extracts

(versus defined medium)

Front 2

defined medium

Back 2

medium for which a precise chemical composition is known

(versus complex medium)

Front 3

slants

Back 3

test tubes containing solid medium that has been allowed to solidify at an angle and the surface of the agar is used for the maintenance of stock cultures of microorganisms

Front 4

deeps

Back 4

test tubes containing solid medium, which has been allowed to solidify in an upright position, and are usually used for anaerobic growth

Front 5

plates

Back 5

solid media in a petri dish

Front 6

Types of Solid Media

Back 6

(1) plates (isolation)
(2) deeps (anaerobic growth)
(3) slants (maintenance)

Front 7

Agar

Back 7

melts at 100°C and solidifies at 40°-42°C

prepared from red algae (Rhodophta)

Front 8

Forms of Sterilization

Back 8

autoclave: moist heat + pressure (most common for liquid media and glass)

dry heat sterilization: flaming, hot-air sterilization (glassware)

filtration: (heat-sensitive liquids or gases, antibiotics)

gaseous chemosterilizers: ethylene oxide, cold-sterilization

electromagnetic radiation: for surfaces

Front 9

nosocomial infections

Back 9

hospital-acquired infections

Front 10

Normal or Resident Microflora

Back 10

microorganisms that occur naturally on or in the body

Front 11

Transient Microflora

Back 11

temporary on body, can't grow on skin because too dry and acidic

Front 12

Infectious dose

Back 12

# of microorganisms requried to establish an infection

Front 13

Colony Morphology

Back 13

characteristics of a bacterial colony

(1) shape
(2) margin shape
(3) elevation
(4) optical properties
(5) surface characteristics
(6) pigmentations

Front 14

Types of Whole Colony Shape

(Colony Morphology)

Back 14

* Round
* Irregular
* Rhizoid

Front 15

Types of Margin Shape

(Colony Morphology)

Back 15

* Smooth, entire
* Lobate
* Filamentous

Front 16

Types of Elevation

(Colony Morphology)

Back 16

* Convex
* Umbonate
* Flat

Front 17

Types of Optical Properties

(Colony Morphology)

Back 17

* Opaque
* Translucent

Front 18

Types of Surface Qualities

(Colony Morphology)

Back 18

* Dull
* Shiny

Front 19

Aseptic Technique Steps

Back 19

(1) Shake tube
(2) Flame loop
(3) Uncap test tube
(4) Flame neck of test tube
(5) Obtain loopful of organism
(6) Flame neck of test tube
(7) Recap test tube
(8) Place loopful on target
(9) Flame loop

Front 20

Streak Plate

Back 20

dilution technique to isolate pure culture

Front 21

STREAK PLATE MISTAKES

confluent growth

Back 21

(1) not flaming between quadrants
(2) re-inoculating each quadrant
(3) streaking back too many times

Front 22

STREAK PLATE MISTAKES

growth only in quadrant 1

Back 22

(1) not streaking back into previous quadrant (or not far enough back)

Front 23

Bacterial Shapes

Back 23

* Coccus = spherical
* Bacillus = rod-shaped
* Spirillum = spiral
* Spirochete = spiral with rod
* Vibrio = incomplete spiral
* Pleomorphic = irregular

Front 24

Bacterial Arrangements

Back 24

* diplo = pairs
* staphylo = clusters (not w/ bacillus)
* strepto = chains
* micro = tetrad or cube

Front 25

Simple stains

Back 25

contain a single basic dye

Front 26

Resolving power

Back 26

closest spacing between two points at which the points can still be seen as separate entities

(0.5 * wavelength)/ numerical aperture

Front 27

Differential Stain

Back 27

distinguishes cell types

primary stain
mordant
decolorizing agent
counterstain

Front 28

Gram-positive bacteria
vs.
Gram-negative bacteria

Back 28

Gram-(+) have peptidoglycan in their cell walls. Teichoic acids. Stain purple.

Gram-(-) have lipopolysaccharides (LPS). Stain pink.

Front 29

Gram Stain

Back 29

PIES =
Purple (crystal violet) = primary
Iodine = mordant
Ethanol = decolorizing agent
Safranin = counterstain

Front 30

mordant

Back 30

binds primary stain to primary cell of interest

Gram stain = crystal violet
Endospore stain = heat
Acid-Fast stain = heat

Front 31

Why is ethanol used as the decolorizer in the Gram stain?

Back 31

The alcohol is unable to leach out the crystal violet-iodine complex in peptidoglycan with Gram-(+) bacteria.

In Gram-(-) bacteria, alcohol penetrates the LPS.

Front 32

Why should you not trust a Gram stain on a culture more than 24 hours old?

Back 32

Because as the bacteria age and use all the available nutrients they are unable to put as much peptidoglycan in their cell walls.
= Gram-(+) could appear Gram-(-)

Front 33

besøke (-te, -t)

Back 33

visit

Front 34

Endospore

Back 34

Specialized dormant structure that is commonly found in certain Gram-(+) rods, such as in genera Clostridium and Bacillus

Front 35

Cryptobiotic state

Back 35

no metabolic activies are occuring

Front 36

Sporulation

Back 36

process of endospore formation within a vegetative cell

(1) spore septum (ingrowth of plasma membrane) separates small part of cell
(2) creation of forespore (w/ double-layer plasma membrane but w/o cell wall
(3) peptidoglycan laid down (layer called cortex)
(4) spore coat produced

Front 37

Location of Endospores

Back 37

* Central
* Terminal
* Subterminal

Front 38

Germination of endospore

Back 38

endospore returns to a vegetative state

Front 39

Outgrowth of endospore

Back 39

visible swelling due to water uptake and synthesis of DNA, RNA, and bacterial proteins

Front 40

Endospore Stain

Back 40

* Malachite green = primary
* Heat = mordant
* Water = decolorizer
* Safranin = counterstain