Download Lab Final, part 2 | MCB 2610 - Fundamentals of Microbiology and more Quizzes Biology in PDF only on Docsity!
Know why the motility agar turns
red
Red indicates the flight path of the organism. If Test tube is all red, the bacteria is motile and is capable of growing in areas of agar which have lower oxygen levels. TERM 2
Know what component of SF agar inhibits
growth and how does it inhibit growth
DEFINITION 2 SF broth contains azide or cyanidewhich inhibits electron transfer along the respiratory chain. TERM 3
Know how to measure the generation time
from the graph
DEFINITION 3 Lag phase, exponential/log phase, stationary phase, death phase.When Number of bacteria Doubles/time.The time required for the population to double in number. TERM 4
Know the mannitol salt info and how do you
test for pathogenicity
DEFINITION 4 Gram positive cocci S. Aureus is pathogenic and is salt tolerant. S. aureus will ferment mannitol to produce acid. Pathogenic s. aureus produces enzyme coagulase causes blood clot. S. Pyogenes cause cell lysis....IF hemolysis occurs then S. Pyogenes is present. Streaked on BLOOD agar.Test for Pathogenicity by screening for indicator organisms such as COLIFORM BACTERIA.Facultative anaerobic, gram negative, non-endosporeforming, rod shaped bacteria that ferment lactose with acid and gas formation. TERM 5
How to interpret fermentation
DEFINITION 5 SF broth contains Brom cresol purple, which is an acid indicator that changes color (from purple to YELLOW) when acid is produced indicating fermentation of glucose.Products such as:=ACIDS: detectable by PH change of an indicator dye (red to yellow)=GASES: detected by accumulation in a small inverted tube submerged in the medium.SUGARS ARE FERMENTED
What is the name of our mascot What is the
names of our TA's
MASCOT: JonathanAMY THEESMARIAM MAHMOUD TERM 7
Look under a microscope at a spore stain and
define if its positive or negative for spores
DEFINITION 7 used for bacillus and clostridium. develop endospore in response to conditions like depletion of nutrients. Spores exhibit resistance to Heat, dryness and other unfavorable conditions.If bacteria is an endospore former, the slide prep should reveal GREEN ENDOSPORES INSIDE PINK VEGETATIVE CELLS. TERM 8
Know the different medias SELECTIVE and
DIFFERENTIAL
DEFINITION 8 Differential medias allow us to categorize bacteria into different categories. through change of color, production of zone of clearing etc. Also sometime include selective agents to retard growth of undesired competitors. MACCONKEY AGAR.Selective medias: contain compounds that inhibit the growth of certain species while allowing others to grow. They select for a certain type of microbe by supplying optimal conditions for its growth, while selecting against some potential competitors from the same habitat. SF MEDIA TERM 9
Know how to interpret ENZYME ACTIVITY
DEFINITION 9 Exoenzymes are secreted by the cells into the environment, and are easily detected by certain CHEMICAL TESTS making them USEFUL indicators in the identification of Bacteria. TERM 10
Know the plates and what they are used for
ie, LT Broth and EMB plates
DEFINITION 10 LT broth enriches the growth of intestinal bacteria (selective and differential) Small tube collects gas from fermentation.EMB agar...is selective contains dyes to inhibit gram positive growth, while containing nutrients to enrich gram negative growth. Is Differential also because lactose fermenters (coliforms) produce dark colored colonies with metallic green sheen (ECOLI) while non lactose fermenters produce light colored colonies with pink color. (E. aerogenes)To obtain well separated colonies which can then be used to establish a pure culture.
Name one method in which one can make a
cell competent.
HEAT SHOCK TREATMENT
TERM 17
If a cell takes up the gene of interest, under
the system that we are utilizing, what color
would the resulting colony be on the plate?
DEFINITION 17 BLUE TERM 18
Would the cells in the colony in question
have a functional or non-functional lac
operon? If they take up the gene of interest...
DEFINITION 18 FUNCTIONAL TERM 19
Define bacteriostatic. VERSUS
BACTERIOCIDAL
DEFINITION 19 A CHEMICAL AGENT USED TO PREVENT BACTERIA FROM REPRODUCINGA CHEMICAL AGENT USED TO KILL BACTERIA TERM 20
An antibiotic that has the ability to inhibit or
destroy many kinds of pathogenic
microorganisms is called:
DEFINITION 20 BROAD SPECTRUM
Explain the difference between a disinfectant
and an antiseptic.
DISINFECTANT IS A CHEMICAL USED ON INANIMATE OBJECTS
TO DECREASE THE NUMBER OF MICROBESANTISEPTIC IS A
CHEMICAL USED FOR THE SAME PURPOSE EXCEPT ONLY ON
LIVING SPECIES
TERM 22
Is mouthwash a disinfectant or antiseptic?
DEFINITION 22 ANTISEPTIC TERM 23
Resazurin is the redox indicator in sodium
thioglycollate broth and a methylene blue
strip is the redox indicator in an anaerobe jar.
Why is a redox indicator needed?
DEFINITION 23 To confirm the absence of O TERM 24
Why shouldnt you shake thioglycollate broth
medium during or after inoculation?
DEFINITION 24 To avoid the introduction of Oxygen TERM 25
How do organisms capable of nitrate
reduction use the nitrate?
DEFINITION 25 They use nitrate as a replacement proton acceptorOrganisms that are able to reduce nitrate use it as a replacement for oxygen as a terminal electron acceptor in anaerobic conditions, a process called anaerobic respiration.
List two items in this room that are
considered fomites.
Doorknobs tables pencils pen TERM 32
Facultatively anaerobic, Gram-negative, non-
endospore forming, rod-shaped bacteria that
ferment lactose with acid and gas formation
with 48 hr are called __________.
DEFINITION 32 COLIFORMS TERM 33
Name and explain the difference between
each type of hemolysis (in terms of
characterization of the clear zone on a blood
agar plate).
DEFINITION 33 Alpha Hemolysis: Partial hemolysis=>Creates green cloudy zoneBeta Hemolysis: Complete Hemolysis with a clearing zone around the bacterial growthGamma Hemolysis= No hemolysis. No change in blood agar TERM 34
When isolating an anaerobe from a
Winogradsky column, would you collect closer
to the bottom or top of the column? And what
is a limitation that we could have in this
exercise (with respect to its growth
conditions)?
DEFINITION 34 Lower end of tube=bottom of columnA limitation could be that the bacterial colony could be contaminated/messed up by prior deep scooping from individuals in earlier sections which would expose the anaerobes to air, thus killing the anaerobes. Anaerobes MUST grow on bottom, CANNOT be exposed to air. TERM 35
Any movement caused by agitation or
vibration of the cells that is not considered
motility is:
DEFINITION 35 BROWNIAN MOTION
Where do you dispose of depression slides?
GLASS BEAKER
TERM 37
Why would one poke holes in some of the
chambers of the EnteroPluri tube?
DEFINITION 37 TO ALLOW FOR AEROBIC RESPIRATION TERM 38
Normally, EnteroPluri tubes are used to test
Enteric bacteria, which are Gram _________
microorganisms?
DEFINITION 38 NEGATIVE TERM 39
When performing a streak plate, how many
times to you obtain bacteria from the original
sample you are given?
DEFINITION 39 ONE TIME FROM THE ORIGINAL SAMPLE TERM 40
What must you do to the loop between each
of the streaks when doing a streak plate?
DEFINITION 40 PLACE OVER THE BUNSON BURNER TO STERILIZE
Whenever you leave the lab classroom you
must wash your hands for
at least 20 seconds with soap and water TERM 47
Test Tubes
DEFINITION 47 Olive colored waste bins UNDER SINKS TERM 48
Glass slides
DEFINITION 48 Sharps container TERM 49
Petri Dishes
DEFINITION 49 BLUE WASTE BINS AT SIDES OF CLASS TERM 50
Micropipettes
DEFINITION 50 Orange Bins on Desk that read Serological Pipettes ONLY
Paper and trash
TRASH BINS with Black Garbage Bags TERM 52
Aseptic Technique
DEFINITION 52 To prevent contamination of yourself and othersContamination control process: also known as Sterile techniqueUsed to transfer specific or desired microbes from one medium/environment to another TERM 53
How to Label the bottom of the Plate
DEFINITION 53 Top: NameLeft: OrganismRight: DateBottom: Section TERM 54
Streak plate method
DEFINITION 54 Quickest and most economical method of bacterial isolation. A bacterial culture sample usually in broth is diluted by spreading it out on an agar surface in a petri dish resulting in isolated colonies.Nutrient Agar or Tryptic Soy Agar plates. TERM 55
Inverting the plate
DEFINITION 55 Inverting the plate prevents drops of condensed water on the lid from falling onto the surface of the agar.If agar is wet, bacteria can swarm across it rather than form isolated colonies.
A smear of the culture is made by
spreading a bacterial suspension on a clean slide and allowing it to air dry. The dry smear is passed through a bunsen burner flame several times to heat fix the bacteria. TERM 62
Heat Fixing
DEFINITION 62 DENATURES bacterial enzymes, PREVENTING AUTOLYSIS.Heat also enhance adherence of bacterial cells to the slide. TERM 63
Positive vs negative ion stain
DEFINITION 63 if the chromophore is a positive ion like methylene blue, the stain is BASICIf the chromophore is a negative ion, the stain is ACIDIC. TERM 64
How bacteria become stained
DEFINITION 64 Most bacteria are stained when a basic stain permeates the cell wall and adheres by weak ionic bonds to the negative charges of the bacterial cell. TERM 65
Staining properties of cells dependent on
DEFINITION 65 Dye strength, rate of ionization of dyes and cell proteins. temp during the stain.
Gram stain
based on cell envelope structure (positive or negative)Characterizes ability to retain crystal violet stain after mordanting with iodine and decolorizing excess stain with alcohol. TERM 67
Gram Positive vs Gram Negative
DEFINITION 67 Positive: retain stain, thick PURPLE cell wall made of peptidoglycanMORE SUSCEPTIBLE by Antimicrobial AGENTS. which inhibit formation of peptidoglycan thereby weakening the cell.Negative: Do NOT retain stain, have outer membrane and an inner layer of peptidoglycan, PINK TERM 68
Capsule Stain
DEFINITION 68 NEGATIVE STAIN, stains background ONLYIF OVAL IN SHAPE=CAPSULEIF IRREGULAR SHAPE=SLIME LAYERRole in virulence (disease causing ability).Made of polysaccharides.. TERM 69
When lactose is fermented
DEFINITION 69 it generates acid products sufficient to turn the neutral red to PINKGram positive bacteria are inhibited by BILE SALTS or crystal violet in the medium thus SELECTING AGAINST THESE ORGANISMS.PINK are lactose fermenters TERM 70
Which organisms are Amylase positive or
negative and how can you tell?
DEFINITION 70 If a bacterial colony is grown on a plate containing starch and produces amylase, a clear zone will appear around the colonies, indication of starch utilization. Verified by flooding the plate with Gram's iodine, a dark blue color will appear everywhere EXCEPT in the clear zone around the colonies. CLEAR ZONES indicate amylase production
