BIOL MicroLAB Midterm

genus then species, name is italicized, or underlined. Genus species

genus then species, name is italicized, or underlined. Genus species

How to write a binomial name

white paper biohazard discard pouches taped to the bench or the red plastic biohazard boxes

where to discard microscope slides, broken glass

orange/red biohazard trash bags in the white metal cans with foot pedal to open

discard petri dishes, plastic tubes, paper trash contaminated with microbial culture

plastic discard tubs on the bottom of the cart, use racks for tubes, remove all labels

discard tube and flask media

plastic discard beakers on the bench tops or in the orange/red biohazard trash bags in the white metal cans with foot pedal to open

discard micropipette tips, swabs, tongue depressors

long plastic discard tubs on the bench tops provided only when needed

discard glass serological pipettes

tall boxes labeled for glove discard only

discard gloves

regular trash cans

discard non-contaminated paper trash

do not discard; return to the top of the cart

discard unused media

culture medium

contains nutrients, like carbon and nitrogen, for cells to grow

complex medium

composed of digests of chemically undefined substances such as year and meat extracts or digests

defined medium

a precise chemical composition is known

broth

liquid medium

agar

solid media

plates

solid media in petri dishes

deeps

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

slants

tests tubes containing solid medium that solidified at an angle

selective medium

medium to favor the growth of certain microbes and to inhibit undesirable competitors

differential medium

a medium that provides a visible indication of a physiological characteristic of a microorganism

sterilization

killing or removal of all living organisms and their viruses from a growth medium like autoclaving

autoclave

sealed device that allows the entrance of steam under pressure

dry heat sterilization

kills by oxidation effects

flaming

one of the simplest methods of dry heat sterilization

hot-air sterilization

sterilizing glassware in an oven

filtration

heat-sensitive liquids or gases are sterilized

gas chemosterilizers

sterilization for heat sensitive objects like a plastic petri dish

ethylene oxide

widely used gas for sterilization

cold-sterilization

no heat is used for sterilization

electromagnetic radiation

microwaves, ultraviolet radiation, X-rays, gamma rays, and electrons for sterilization

ultraviolet radiation

causes damage to DNA, leading to the death of exposed organisms, cannot penetrate solid and is only useful to sterlize exposed surfaces

ionizing radiation

causes ions and other reactive molecules to be produced and these reactive molecules can degrade or alter biopolymers such as DNA and proteins

contaminants

unwanted organisms

asceptic technique

used to prevent contamination of bacterial cultures and the environment

shake culture tube, heat loop, remove cap, flame neck of tube, cool loop, take a loop of microorganisms, flame mouth of tube, return cap

process of asceptic technique

oil-immersion objective

used to observe the cells at 1000x

cells mostly consist of water, so unstained cells may be difficult to see bc of the lack of contrast

why is the oil needed to see at 1000x?

staining cells makes them more visible

how do you make cells more visible?

smear

first step to staining cells, only made from cultures in liquid or on solid medium, a thin layer of cells on a slide

heat fixation

kills the cells, destroying autolytic enzymes, helps cells adhere to slide

prevents the cells from being washed from the slide during staining

Why is adhesion of cells to the slide important?

morphology

shape of cells

coccus, rod/bacillus, and spiral

three types of basic shapes

diplo (pairs), strepto (chains), staphylo (clusters)

three ways cells are arranged

cocci

round shape

bacilli

rod-shaped

spiral

twists

prosthecate cells

organisms that produce prosthecae

prosthecae

cellular appendages that increase cell surface area, which help transport nutrients into the cell

filamentous growth

some actinomycete bacteria, produce filaments or hyphae that form a mycelium

mycelium

network of hyphae

simple stain

a direct stain that uses an aqueous or alcohol solution of a single basic dye, makes cellular shapes and structures visible

negative stain

an indirect stain that uses an acidic dye to color the background, leaving the cells colorless

differential stain

utilize a combination of dyes to demonstrate a chemical or structural component of a cell

Gram-positive and Gram-negative (the gram should always have an uppercase G)

two groups of gram stains

peptidoglycan

repeating disaccharides attached by a polypeptide to form a lattice in the cell walls

Gram-positive has many layers of peptidoglycan and a rigid structure, also contains teichoic acids; Gram-negative has less layers, lipopolysacchardies (LPS) outermembrane, no teichoic acid

How does Gram-positive cells differ from Gram-negative?

teichoic acids

copolymers of glycerol phosphate and ribitol phosphate and carbohydrates linked by phosphodiester bonds that provide the wall of antigenic specifity

primary stain

for a gram stain, its crystal violet

mordant

iodine in a gram stain, binding to crystal violet to form a not easily removed complex

decolorizer

ethanol in a gram stain, removing the basic dyes like crystal violet

counterstain

safranin in a gram stain

Gram-positive staphylococcus epidermis, gram-negative purple spirals

When viewing a gram stain under 100x what do you see?

younger, less than 24 hours since older might have a cell wall structure that may be compromised, causing cells to lose the ability to retain the primary stain

Is gram negative more consistent on young or older bacteria?

purple

What color are gram-positive?

red

What color is gram-negative?

endospore

dormant structure that is commonly produced by certain Gram-positive rods, forms when nutrients or water is depleted, highly durable dehydrated metabolically dormant structures

they are so resistant, their survival could produce toxins and cause disease

Why are endospores dangerous?

Geobacillus stearothermophilus

bacterial endospores that are used to indicate the effectiveness of autoclaves

vegetative cell

one that can grow and divide under optimal conditions

cryptobiotic state

endospores are in this state; no metabolic activities are occurring

sporulation

when nutrients or water become depleted, this process will begin coverting the vegetative cell into a single endospore; process of endospore formation within a vegetative cell

spore septum

isolates the replicated chromosome and a small amount of cytoplasm in the first stage of endospore formation

forespore

structure that is a double-layered plasma membrane surrounding the genetic material

cortex

layer where peptidoglycan will be laid down between the two plasma membranes

spore coat

a coat around the outside of the structure formed by spore proteins; responsible for the resistance of the endospore to harsh chemicals

core

consists of the cell wall, cytoplasmic membrane, cytoplasm, and nucleoid

central, terminal, or subterminal positition

Where can endospores be located?

small acid-soluble proteins (SASPS) and calcium-complexed dipicolinic acid

protecting the endospore DNA from damage

outgrowth

the synthesis of DNA, RNA, and bacterial proteins

malachite green

Primary stain in endospore stain

safranin

Counterstain in endospore stain

mycobacterium

What culture is used in acid-fast stain?

mycolic acid

makes mycobacterium cells hard to stain; resists decolorization

acid-fast

since mycobacterium resist decoloration they are classified as?

hydrophobic nature

reason for the wrinkled appearance of mycobacterium; make cells impermeable; slow growth of mycobacterium

egg albumin

help dispense the mycobaterial cells when making a smear; high protein content; help make smear for acid-fast stain

carbolfuchsin (magenta dye)

primary stain for acid-fast solutions

acid-alcohol

removes fuchsin dye from cells that are not acid-fast

methylene blue

counterstain for acid-fast reactions

blue

What color are cells that are not acid-fast?

capsule

contains layers of polysaccharide that surrounds the cell wall of bacteria

Azotobacter vinelandii

What is one of the bacteria that produces a polysaccharide capsule?

presence of excess nutrient

What do capsules need to be formed?

desiccation of cell

water prevents this of the cell

virulence factor

if a capsule enhances the organism’s ability to cause disease

avirulent

nonencapsulated form that does not cause disease

congo red

primary stain for capsule stain

Maneval’s stain

darkens the background and stains cells in capsule stain

background is gray to darkblue/purple, cells are red, capsules are unstain and appear clear around the cell

What color is the background and cells in a capsule stain?

to isolate and maintain a microbial culture

What are steak plates for?