Lab Exam 1 - Quizlet Import

ubiquity

microbes are present nearly everywhere

pathogenic

able to cause disease/infect

reservoir

Any person

opportunistic pathogen

does not usually harm host

example of opportunistic pathogen

Staphylococcus aureas

Saphrophytes

obtain nutrition from dead tissue (fungi)

What must a microorganism acquire from its environment in order to grow and replicate?

food

optimal environmental conditions

temp

why is blood agar used

-it is useful for detecting hemolytic ability of gram POSITIVE bacteria
-used for the isolation and cultivation of many fastidious/non-fastidious types of bacteria

alpha hemolysis

partial lysis and incomplete destruction of RBCs and produces greenish discoloration of the agar around the colonies

beta hemolysis

complete lysis (destruction) of RBCs and hemoglobin results in a clearing of the medium around the colonies

gamma hemolysis

no hemolysis (no destruction) of RBCs and appears as a simple growth with no change to the medium

Why is morphological characterization useful?

-Important tool for identification
-Allows for distinction in mixed samples

Why are microbial controls (germicides) useful?

antiseptic agents that destroy harmful microbes and decrease spread of pathogens

friable

growth that is dense and opaque with a smooth edge

filiform

crusty growth

spreading edge

solid growth radiating outwards

pellicle

floating surface membrane in broth

sediment

growth sinks to the bottom

uniform fine turbidity

uniform cloudiness in broth

flocculence

clumpy growth in broth. floating growth

purpose of an autoclave and description of how it works

pressure is exerted onto a steam/vapor which generates heat and force

How to test autoclave functionality and interpret results.

sterilize endospores or heat-loving bacteria

proper loop sterilization technique

flame loop from bottom to top for 6 seconds

proper pour plate technique

mixed population of bacteria is diluted into tubes of nutrient agar
medium is then poured into petri dish for incubation
colonies are formed on surface and in the medium
*must be performed quickly because the liquid agar will solidify quickly in the tubes

Decontamination

lowest level of control

decontamination usually includes

physical cleaning with soaps or detergents and removal of all or most organic and inorganic material

Disinfection

divided into 3 subcategories

low

medium and high

all sub levels kill high #'s if not all targeted pathogens but not large # of bacterial endospores

disinfectants are usually

liquid chemical agents

antiseptics

disinfectants that are designed to reduce or eliminate pathogens on or in living tissues

sterilization

the complete elimination or destruction of all microorganisms

Why are techniques to isolate single colonies useful?

-to study the single colony to study morphology

aseptic techniques are useful because

they prevent contamination

understanding why calibrating an ocular micrometer is useful

useful to know the length in a real measurement to be used to find real dimensions without having to switch back to the stage micrometer

spread plate technique is used to

isolate or quantify cell densities

in properly diluted samples

chromogen

the colored molecule of a stain

autochrome

charged portion of a chromogen that allows it to act as a dye through ionic or covalent bonds between the chromogen and the cell

How and why does a basic stain interact with a cell?

the auxochrome becomes positively charged as a result of picking up a hydrogen ion or losing a hydroxide ion and then is attracted to the negative charge on the surface of most bacterial cells

3 things heat fixing does

-kills the bacteria
-makes them adhere to the slide
-coagulates cytoplasmic proteins to make them more visible

why is the crystal violet not decolorized in gram positive cells

the thicker peptidoglycan is like a chain link fence that holds in the crystal violet die much better than the thinner peptidoglycan of the gram negative cell walls with more lipids

gram positive

purple

gram negative

pink

antibiotics

natural antimicrobial agents produced by microorganisms

zone of inhibition

a clear zone around antibiotic disc where bacteria do not grow

drugs that kill the organism are said to be

bactericidal

drugs that stop the bacteria from dividing but do not kill them

bacteriostatic

Chloramphenicol

prevents peptide bond formation

Ciproflaxin

interferes with DNA replication

penicilin

inhibits cross-linking of cell wall's peptidoglycan

Streptomycin

blocks initiation complex formation in protein synthesis

tetracycline

blocks attachment of aminoacyl tRNA to A site on ribosome

Trimethoprim

inhibits purine and pyrimidine synthesis

resistance mechanism chloramphenicol

poor uptake of drug

resistance mechanism if ciprofloxacin

altered target

resistance mechanism penicillin

one or more of:

• altered target

• poor uptake of drug

• production of B lactamases

resistance mechanisms Streptomycin

altered target

resistance mechanism tetracycline

efflux mechanism

resistance mechanism trimethoprim

altred target

how to measure zones of inhibition

using a metric ruler and a dark

Hemagglutination

clumping of red blood cells

Type A blood has

A antigens

Type B blood has

B antigens

AB blood has

A and B antigens

Type O blood has

no antigens

positive d antigen

Rh+ blood