mbio exam 2 Flashcards
must Have O2 to survive
Obligate aerobes
can grow in the presence or absence of O2
Facultative anarobes
Do not need O2 but can survive in presece of O2
Aerotolerant & anarobes
Survive only when levels of O2 are low
microaerophiles
Survive only when levels of CO2 are high
Caphophiles
Any o2 eill kill the bacteria
Obligate Anarobes
the ability or inablity to live in the presence of O2
aerotolerance
Bacteria will grow in the tube where the O2 level is _ for that organism.
optimal
Autoclaving a capped tube of media will remove most of the free O2 . as the media cools O2 will start to _ back into the media. Creating a __ where there will be __ O2 at the surface of the media while the bottem of the tube will have ___ O2.
Diffuse
Concentration Gradiant
Higher
No
Adjusting to new enviroment ___ metabolic activity ( no division) and length of lag depends on how extream of an enviroment change.
This is the-Lag Phase
High
Bacteria begin to divide at maximum growth rate the growthis __ and will last as long as sufficent __ and favorable conditions are present
this is the- Log Phase
exponitial
nurients
Eventually nutrients become limited and ___ products begin to accumulate. In this phase the ___ rate equals the ___ .
this is the- Stationary phase
Wast
growth
death rate
All ___ have been depleted and the accumulated wast products make the enviroment ___.
this is the -Death Phase
Nutrients
Toxic
Phases of the bacterial growth curve
lag phase
log phase
Stationary phase
Death phase
the bacterial growth curve provides ______ information about a bacterial species.
length fo time in each phase of growth
optimal growth conditions
mean generation time of the organism.
bacterial are ___ and can be found in many diffrent habitates.
Ubiquitous
Some Possible conditions that bacteria may encounter _____,____, and _____
temps
PH
Osmotic pressure
Minimal, optimal and maximal temperatures at which bacterium can grow
Cardial Temperatures
Grow @ range of < 20 C
found in ___ , and ____.
Human Pathogen?
Psychrophiles
23-86 F
alpine soil
Ice feilds
No
Grow at range of 0 C- 30 C ____F. found in ____, ____ and ____.
Human Pathogens?
Psychrophiles
23-86 f
soil, surface water, and food.
Yes can be human pathogens
Grow at range of ~15 c to~40 c _____F
Human Pathogens?
Mesophiles
59-130 F
Yes can be human pathogens and cause deisease.
Range ~40 to ~75 C ______F found____.
Thermophiles
104-167 F
found in hot springs
Grow at a range of ~65C to ~110 C _____F. where are they found?
Hyperthermophiles
149-230 F
ocean floor
thermal vents and ridges
PH is the ______ of ______ ions measured on the _______ scale?
Concentration
H+
logmarihmic
As H+ increases the PH ______ and the solution becomes ______?
goes down
acidic
As H+ decreases the PH ______ and the solution becomes ______?
goes up
Basic
three major catogories for bacteria based on PH?
Acidophile
Nuetrophile
Alkaphile
grow well in acidic enviroments…
Ph of <= 4.5-5.5
Acidophile
Stomach acid has a PH Of?
1-2=PH
Grow well at neutral Ph between 5.5 & 8
Nuetrophile
Most human pathogens are ______
Neutrophiles.
Human blood has a PH of ?
PH- 7.4
Grow well in basic/ a;la;ome PH of >= 8-8.5
Alkaphile
H2o is essential for all forms of life including bacteri. Bacteria need water to maintain_______. this is necessary so that cells do not _____ or ______.
Turgor pressure
lysis
plasmolysis
To regulate this turgor pressure bacteria use _____ and _____ ions to maintain a _______ in which there are more ions inside the cell than outside.
Na+
K+
Concentration gradiunt
We know that through the process of _____ water moves from areas of ____ ion concentration to areas of ____- concentration to maintain/ achieve equilibrium.
Osmosis
low
high
______ is the mesure of the force with which H2o flows during osmosis.
Osmotic Pressure.
three types of Osmotic enviroments a bacteria can encounter.
Hypotonic
Isotonic
Hypertonic
Higher solute inside the cell than out
low osmotic pressure
_h20 moves into the cell
cell wall lysis
Hypotonic
equal solute can go inside and outside the cell
Isotonic
Low solute can be inside than outside the cell
High osmotic pressure
H20 moves out of cell
cell wall plasmolysis
Hypertonic
Salinity amount of salt in a solution can affect the growth of bacteria. most bacteria grow in concentration less than ____ %
3%
Human pathogens prefer the _____% of ______ and _____.
.9% nacl
blood
Urine
certain bacteria love and grow optimally in Nacl concentrations greater than 3% and are called ________.
Haleophiles.
In addition you also find Extream Halophiles that only survive in Nacl concentration of ____ to ____.
15
25
If bacteria can grow over a wide rage of Nacl cnacentrations it is called _________.
osmotolerant bacteria.
Direct count metohods
Plate count
Filtration
Most probable Numbers
Direct Counts
indirect count metods
Metabolic activity
dry weight measures
Turbidity
a Spectrophotometer is used to measure __________ of a sample.. A _________ of light is passed through the sample where the photo detector converts the light energy into an ________ which can be used to mesure the amount of light ________ by the sample.
turbidity
Monochromatic ( single wavelenght)
electric signal
transmittence % of absorbance
______ or _______ is the amount of light neither transmitted or reflected by the sample.
absorbance
optical density
absorbance range from 0-1.99 A anything above that needs to be ______.
diluted
There is a ______ relationship between the amount of light absorbed and the concentration of cells in a sample.
Direct -linerar
Low absorbance =
low # of bacteria
Lowest turbidity
high absorbance
High # of bacteria
Higher turbidity
what do Mc farland standards repersent?
A set of refrence smaples of diffrent turbidity that can be used to estimate the # of bacterial cells in a sample.
Bacteria replicate by
Bianery fission
is the time it takes bacteria to get from 2^x to 2^x+1
doubling /generation time
it takes _____ salmonella to cause illness and theier doubling time is about _____ min.
500
20
NF=Ni(2^n)
Nf=#of cells at final time point
Ni= # of cells at initial time point
N=#of generations
doubling times vary by species and enviroment factors and can range from ______ min to ______ days . the average doubling time is _____ to ____ min.
10 min
30 days
20 min
60 min
_______ can be used to check the various effects of enviromental changes to a bacteriums growth.
closed growth system
In a closed growth System No ______ are added and No ________ are removed
nutrients
waste products
Mesaures a bacterial population
Mesaures the number of viable cells (cfuS)
Plate counts
Stattistical estimates metod for mesuring a population ( mpn /100 ml)
Most portable Numbers
Mesaures a bacteria population based on the fact that bacterium cannot pass through pors of membran filter.
filtration
Mesaure the number of bacteria cells in a sample.
manual counts using Petroff Hausser counting chamber
Direct Counts
estimates bacterial #’s by measuring the metabolic activity of a bacterial population… production of O2 and acide.
Metabolic activity
Estimate bacterial #’s by mesuring the weight of bacterial population
dry weight mesure
Estimate bacterial #’s by mesureing turbidity of growing bacteria.
turbidity.
what are the three fluid thioglycollate medium
Sodium Thioglycollate
L-cystine
Resazurin
reducing agent for Sodium Thioglycollate
reduces O2—->H2O
reducing agent for L-cystine
reduces O2—-> H2O
reducing agent for resazurin
oxidation reduction indicator
red/pink= presence of O2
yellow/straw= absence of O2
can aerotolerance be determined with agar plates? how?
yes however plates have to be incubated under arobic and anarobic conditions.
Methylene Blue indicator strip in gas jar turns_____ in the ____ of _____.
Blue
presence
O2
white = absence of O2
In the Anarobic Jar experiment if conditions are not achived what happens?
strip remains blue - means there is a hole in the bag
what does the Oxidation Fermintation test tell Us?
which catabolic pathway a bacteria uses
O2 is the final electron acceptor
Must be in an AEROBIC enviroment- oxygen
Aerobic respiration/Oxidation
Other ORGANIC molecule is the final electron acceptor
either AEROBIC or ANAEROBIC
(presence) or ( absence)
Fermentation
occures only in the presence of O2
Aerobic respiration
can occure in the presence or absence of O2
Fermentation.
produces small acidic intermediat compounds
Arobic respiration.
large acid compounds produced
Fermentation
Media has two important Componets
Carbohydrates- glucose, lactose, sucrose ect..
Ph indicator- bromothmol Blue
Oxidation Media is ______… with a PH of____
Green
PH 7.1
oil layer is added to make enviroment anaerobic and promote fermentation.
when ph drops below 6 = more acidic…. the media turns yellow.
Oxidation results ( only pathway used)
Oil
Green
no breakdown
no acid= PH
glucose cannot be broken down under anarobic conditions.
Oxidation test possible outcomes
No Oil
Yellow @ Top ( O2 present)
Some breakdown
Some Acid (lower PH)
glucose broke down —-> moderate amounts of acidic compounds made =( drop in PH)
Fermentation Results
Oil
Yellow
Breakdown
Acid ( lower PH)
Fermentation Test results
No Oil
Yellow
breakdown
Acid Lower PH
No utilization of Carbohydrate test results
Oil
green
no breakdown
No Acid= PH
No utilization of carbohydrate
No Oil
Green
no breakdown
No Acid=PH
No utilization of Carbohydrate
or
Blue- green
indicating breakdown of protiens
basic/ alkaline Higher PH
what does the phenol Red Broth tell us?
it determins what carbohydrates a bacterium can ferment.
this is a differental test since the ability of one species to ferment a carbohydrate may be diffrent than that of another.
_______ is not the only sugar that can be used to start glycolysis.
Glucose
the end products for fermentation are usally _________.
acidic compunds
______ can also be an end product of fermentation
gas
three componets of Phenol red broth
Base- no carbohydrate in the media ( so you can add the one you want to test.
PH indicator- phenol Red
Durham Tube- to check for gas production- places upside down to see if gas bubbles are produced
Four possible outcomes for Phenol red Broth
Fermentation - no gas
fermentation - gas produced
no fermentation -no gas
no fermentation - protien breakdown
test results for fermentation - no Gas
yellow
lower in PH acid
No Gas
Record A/-
test results fermentation Gas produced
yellow
Acid ( ower in PH)
Gas
Record- A/ G
Fermentation test results
No fermentation - No Gas
Red
No Acid = PH
Record -/-
fermentation test results
no fermentation - protien breakdown
bright pink
Basic/alkaline ( higher PH)
record K
Catalase Test tells us what?
determins the presence or absence of the enzyme catalase in the bacterium
what is the diffrence in Aerobic and Anaerobic Respiration?
the diffrence is the final electron acceptor.
the final electron acceptor in Aerobic respiration is ?
O2
the final electron acceptor in Anaerobic Respiration
Nonoxygen molecule
electrons are passed down a chain of molecules that alternate between becoming _______ or ________.
oxidized
reduced
During this passing of electrons some can escape called________. when this occurs a ____________ will be produced.
premature electron leakage
superoxide O2
_____ is extreamly toxic to bacteria and they must be able to _____ to survive.
O2
break it down
Bateria use a enzyme called__________ the reaction is?
SuperOxide Dismutase
O2 + SOD —> O2 + H2O2
_____ is not quite as toxic as ____- but bacteria must still break it down further. the reaction is?
H2O2
O2
H2O2 + Catalase —> H2O2 + O2 ( gas)
catalse test has two important components
bacteria - smered on glass slide
H2O2- test reagent
two possible outcomes = catalase positive
catalase negative
results for catalase negative
no catalase enzyme
No O2 gas produced
results for catales test
catalase positive
catalase enzyme present
O2 gas produced
what does the oxidase test tell us?
the oxidase test determins the presence or Absence of cytochrome C oxidase in the ETC of the bacterium.
Etc’s can very from organisum to organisum. some are similar to those found in eukaryotic mitochondria. These mitochondria like ETC’s consist of 4 enzyme complexes used to transfer electrons. The last complex is Complex IV ( cytochrome C Oxidase) and specifically transfers from cytochrome C to O2.
oxidize - loss of electron
reduction - gain of an electron
_____Catalyzes movement of an electron from one molecule to another?
Cytochrome C Oxidase
______ is a chemical that donats an electron and when doing so changes color. In our experiment it was Tetramethyl-p-phenylenediamine (TMPD)
Chromogenic Reducing Agent
reaction of oxidase test
TMPD + cytochrome C Oxidase —–> TMPD is OXidized ( loss of electron)
TMPD turns what color when it is oxidized and loses an electron?
Blue
three possible outcomes for Oxidase test?
Oxidase Negative
Oxidase positive
False positive
what do the test results mean
Oxidase Negative
TmPD on Window
No cytochrome C Oxidase
No Oxidation of TMPD
No color change
what do the test results mean?
Oxidase Positive
TMPD on Window
Cytochrome C Oxidase
Oxidation of TMPD
Blue
what do the test results mean?
False Positive
TMPD is unstable
and can lose its electron
with or without Cytochrome C
Oxidase
to prevent test must be read in 20-30 secounds
what does the nitrate reduction test tell us?
determins is the organisum can use nitrate for denitrification or ammonification.
Aerobic Respiration
aerobic and facultative aerobic organisms
O2 is the final electron acceptor
Anaerobic Respiration
Nonoxygen molecule is final electron acceptor.
If ______ is used as the final electron acceptor then the bacteria can perform either.
NO3
______ is a multiestep process performed by a group of enzymes that leads to the production of N2 (Nitrogen Gas)
Denitrification
_______ is a multistep process performed by a group of enzymes that lead to the production of NH4(ammonia)
Ammonification
what is the pricipal of the Nitrate reduction test?
1st step in either denitrification or ammonification is the reduction of nitrate (No2) to Nitrite ( No2) by the enzyme Nitrate Reductase.
Nitrate Broth contains
Potassium Nitrate ( KNO3) - source of Nitrate
Duraham Tube - to monitor gas production
there are no color indicators in this test
three possible outcomes for the Nitrate Reduuction Test are?
first you need to know the results of the OF test or Phenol Red Broth test is the organisum a Fermenter or Non fermenter.
- organisum is a Non fermenter
- organisum is a fermenter.
- organisum is a fermenter
Nitrate reduction test results
Organisum is a Non Fermenter
Gas-Yes
Nitrate reductase present
Denitrification- source of gas
Nitrate Reductase Positive
Nitrate reduction test results
Organisum is a Fermenter
Gas-yes———–> type of gas is unknown and test must proceed
Addition of Reagent A
Addition of Reagent B
Red color
Nitrate Reductase Positive ———> Nitrate ( NO3) converted into nitrate ( NO2) which reacted with water in broth to form (HNO2) nitrous acid which Reagent A & B reacted with.
Nitrate reduction test results
Organisum is a Fermenter
Gas–yes Or No
Addition of Reagent A
Addition of reagent B
No Red Color—–> possibility #1 orgnisum does not have Nitrate Reductase
———-> possiblity # 2 .. organisum reduced all nitrate to nitrite and all the nitrite was converted to other nitrogen compounds.
After adding Zinc powder
red color—->nitrate still present—>Nitrate Reductase Negative
No Red Color—>no Nitrate present–> Nitrate Reductase Positive
what does the Decarboxylation Test tell us?
Determins the presence or absence of a specific Decarboxylase in a bacterium.
Is an enzyme that catalyzes the removel of an amino acids carboxyl group.
Decarboxylase
it acts on specific ameno acids
End products of decarboxilation are Polyamines ( compunds with 2 or more amine groups.)
A co enzyme is required called Pyridoxyl Phosphate
are important in maintaining the correct internal PH of a bacterial cell.________ are alkaline compounds that raise _____
POLYAMINS
Polyamines
PH
other importances of Polyamines
Regulation of gene transcription and translation
role in biofilm formation
Principal of the Decarboxylation Test.
Mollers Decarboxylase Base medium contains :
protiens ( beef extract and peptones
Carbohydrates( glucose)
Pyridoxal Phosphate (co enzyme)
Ph indicator ( bromocresol Purple)
Principal of the Decarboxylation Test.
—-Also specific amino acids are added to test for corresponding decarboxylasae.
HCL is added so that the initial PH is 5.2-6.2 since decarboxylases are induced /made under acidic conditions.
After media is inoculated a layer of oil is added to make an anaerobic enviroment since it stimulates fermentation( and acide production which futher lowers PH)
three possible outcomes for Decarboxylation Test.
- decarboxylase Negative- no fermentation
- Decarboxylase Negative- fermentation
- Decarboxylase Positive.- fermentation
Results for Decarboxylation Test
Decarboxylase Negative
no fermentation
No acid produced = PH
No decarboxylation induced
no alkaline products = PH
No color change ( copper)
Decarboxylase Negative
fermentation
Acid produced ( lower PH) yellow
No decarboxylation induced.
No alkaline products = PH
Tube remains Yellow
Decarboxylase Positive
Fermentation
Acid produced induced
decarboxylation induced
alkaline products produced ( raises PH)
tube turns purple
