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206 Cards in this Set

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  • Back
What do we add to make agar solid?
Are the exact ingredients of a complex media known or unknown?
Are the exact ingredients of a chemically defined media known or unknown?
What type of media do we use in lab?
what are two examples of unknowns?
beef digest, yeast digest
Give three examples of selective media:
salt, bile salt, and sugars
What is a differntial media
a media that differentiates between microorganisms growing on the media
Describe the three steps in making the salt agar differential media discussed in class:
1. add 7.5% salt conc...only those that can grow under these conditions will. 2. add sugar (mannitol). 3. add phenol red (pH indicator)
Staphylococcus aureus can grow on 7.5% salt agar, but does it use mannitol or not?_______. Does it produce acid?_____. What happens to the pH?_____
Yes it uses mannitol, yes it then produces acid, pH goes down
If the pH is more acidic, what color will it show up on the plate?
If the pH is more basic what color will it show up on the plate?
Staphylococcus can grow on a 7.5% salt agar, but does it use mannitol? Does it produce acid? What happens to the pH?
No, it does not use mannitol. No, it does not produce acid? The pH goes up.
Sulfonamides are a type of...
Sulfanomides are analogs of this:
PABA (p-aminobenzoic acid)
PABA is part of an enzyme complex used to make this:
folic acid
Folic acid is part of an enzyme complex necessary to make these:
What are the purines?
adenine and guanine
What are adenine and guanine used for making?
DNA, RNA, and adenine in ATP
Sulfonamides work by a process called:
competitive exclusion
With competitive exculsion, Sufonamides compete with _______ in the enzyme complex used to make_______.
PABA, folic acid
Can our bodies make folic acid?
Where can we get folic acid?
cereals, supplements
What are 4 effects of sulfadrugs on bacteria?
1. inadequate folic acid
2. inadequate A and G
3. inadequate nucleic acids
4. selectively toxic
Where do animals get their folic acid from?
What are the four stages of the bacterial growth curve?
Lag phase, exponential phase, stationary phase, and death phase
What goes on the Y-axis in a bacterial growth curve? The X-axis?
log # of cells, time
What happens during the lag phase of bacterial growth?
preparation of growth
The lag phase might take a longer period of time if....(3 things) and why for each
cells are old (depleted amts. of ATP, ribosomes, etc) cells growing in a new medium (new enzymes must be made), if cells are injured (repair necessary)
What is the exponential growth phase of the bacterial growth phase?
The maximum rate of reproduction
During which phase of the bacterial growth curve are cells most vulnerable?
Why are cells most vulnerable to antibiotics, heat (denaturing of proteins) and viruses (more likely to be taken in because the cell is taking things in and out) during the exponential growth phase?
Because these interfere with metabolism and binary fission
What has happened when a bacterial cell as reached its stationary growth phase?
It has reached its carrying capacity
What does carrying capacity mean?
death rates = growth rates
What are four reasons why a bacterial cell might reach its carrying capacity?
nutrients used up, environment changed, oxygen gone, wastes accumulated
What are cells in the stationary growth phase hard to kill? (three reasons)
1. They have chaperones which protect proteins by folding them. 2. They have DNA-binding proteins which protect the DNA. 3. Ability to form endospores. 4. etc.
During the death phase, is some growth still present?
What is true about death rates and growth rates during the death phase
death rates > growth rates
What does binary fission do to the size of a population?
doubles it
What is generaion time?
the time it takes a population to double
What does No represent?
initial population size
What does Nt represent?
population size at time t
What does n signify?
# of generations in time t
What is the mathematical expression of binary fission?
Nt = No x 2^n
If Salmonella entiritidis's generation time is 30 mins, and No= 10 cells, solve for Nt after 4 hours:
Nt = 10x2^8
Nt = 2,560
What is an infectious dose?
The number of cells required initially in order to cause an active infection.
Why is microbial growth expressed on a logarithmic scale?
It makes graphing easier
On what time of scale is exponential growth measured on?
A logarithmic scale
log_10_1000 = ?
log_10_? = 2
log_10_10,000 = ?
Why would you want to know the number of generations a population passed through?
If you wanted to determind how fast an organism grows under different circumstances (to enhance or slow growth)
What steps would you take if you wanted to grow microorganisms under conditions that support minimum generation time and maximized growth rate?
1. Measure population at No and Nt
2. Calculate # of generations
3. Calculate k+g
4. Determind best growth conditions
(See handout)
How does a Petroff-Hauser Chamber count cells?
The number of live and dead cells in a grid are counted and multiplied.
Which technique of measuring population size counts the number of live and dead cells on a grid?
Petroff-Hauser Chamber
What is an advantage and disadvantage of the Petroff Hauser Chamber?
It allows you to compare populations sizes, but counts both dead and live cells.
What machine is used to help measure levels of turbidity?
Spectrophotometer (Spec 20)
What is turbidity?
The cloudiness of a culture
(which is then related to the dry weight of the culture)
Does a Spec 20 count live and/or dead cells?
What is the usefulness of a Spec 20?
It is a snapshot in time...if you don't really care about #'s.
Are the numbers of cells measured in a Spec 20 exact?
No, relative values
The higher the population, the _______the absorbance and the _______ the turbidity in a Spec 20.
higher, higher
The higher the population, the ______ transmitance in a Spec 20.
Does a viable cell count, count all cells, just live cells, or just dead cells?
Just live cells
What are the two steps taken before counting colonies with a viable cell count?
Inoculate the media and then incubate it.
When doing a viable cell count, what is the assumption being made?
One colony represents one cell in the original colony. (CFU)
What does CFU stand for?
Colony forming unit
What makes viable cell counting a hassel?
It requires serial dilution.
What is serial dilution?
When you suspend microbial cells in a solution, then remove some from that solution into a new solution, and then again and again and again to isolate colonies.
All microorganisms grow on all media types, true or false?
False, not all do...(consider this when doing a viable cell count)
Environmental factors:
check power point
plot a graph of temp vs. rate of growth: including min. temp of growth, optimum temp of growth and max temp of growth.
min, slope up, optimum, shoot down, max, temp on x, rate on y
What are two effects of high temperature on growth?
proteins denature and membranes will melt usually causing death
Are the effects of high temperatures on growth reversable?
No, they are permanent
What are two effects of low temperatures on growth?
enzymes stop working, membranes solidify
Are the effects of low temperatures on growth reversable?
What is the upper temp limit of protozoa (eukaryotes)
50 C
What is the upper temp limit of fungi and algae?
60 C
What are the upper temp limits of prokaryotes?
113 C
Why can knowing the optimum temp of growth be useful?
It can help us classify organisms into groups.
Name five groups separated by optimum temperatures.
Psychrophiles, psychotrophs, mesophiles, thermaphiles, and hyperthermophiles
What is the optimum temp desired by psychrophiles? What are the membranes in psychrophiles composed of?
< or = 15 C, mostly unsaturated fatty acids
What can happen to psychrophiles in temps greater than 20 C? Where do most psychrophiles live?
leaky membranes, Arctic and Antarctic habitats
What is the optimum temperature desired by mesophiles? What are their membranes composed of?
20-45 C, mix of unsaturated and saturated fatty acids
Most human pathogens can be catagorized as...
The optimum temperature desired by thermophiles? Their membrane consists of?
55 - 65 C, lots of saturated fatty acids
What types of enzymes do thermophiles have?
Heat Stable Enzymes
Where do most thermophiles live...3 places?
compost piles, hot springs, hot water lines
What is the optimum temp desired by hyperthermophiles? Which other group are their adaptations similar to?
80-113 C, thermophiles
Why do hyperthermophiles have DNA with such a high melting point?
high G-C content
What are proteins that refold other proteins in hyperthermophiles called?
What are chaperonins? Where are they found?
Proteins that refold others, hyperthermophiles
What is unique about oxygen metabolism?
It produces more enery than other forms of metabolism
What are three problems with oxygen use?
1. atmospheric Oxygen is easily reduced forming a superoxide radical (O_2_ .-) which is very reactive and unstable.
2. The superoxide radical can from hydrogen peroxide which is dangerous.
3. It can be toxic because it was powerful oxidizing agents
What is the problem with powerful oxidizing agents?
They inactivate active sites at enzymes, denature proteins, and damage DNA
Name three protective enzymes against O2 problems:
superoxide dismutase (SOD), catalase, and peroxidase
What does SOD do?
20_2_.- + 2H+ --> H_2_O_2_ + O_2_
Why is SOD only a partial solution?
it produces hydrogen peroxide which is toxic
What does catalase do?
2H_2_O_2_ --> 2H_2_O + O_2_
What does peroxidase do?
H_2_O_2_ + NADH + H+ --> 2H_2_O + NAD
Obligate aerobs require blank to grow and have/don't have SOD and catalase
O2, have
An example of an obligate aerob is
Obilgate anaerobes require blank to grow and have/don't have SOD or catalase
require no O2, don't have
An example of an obligate anaerobe is blank which can cause:
Clostridium, gangreen, tetanus
Facultatives grow best with blank and have/don't have SOD/catalase
with or without O2, but best with O2, have
A few examples of facultatives include blank which can:
Saccaromyces cerevisiea, Entrics: Escherichia (food poisoning), Salmonella (food poisoning), Shigella, Proteus (urinary tract infection), Yersinia (bubonic plague), and Klebsiella (pneumonia)
Microaerophiles require blank to grow and have/don't have SOD and catalase...
little O2, too much is toxic, have
Two examples of microaerophiles include blank and cause:
Campylobactor spp. (gastroenteritis), Treponema pallidum (syphilis)
Aerotolerants blank to grow:
don't use O2
Aerotolerants grow equally well in presence or absence of O2, true or false?
What is an example of an Aerotolerant and what does it do?
Streptococcus fascitis, scarlet fever, strep throat, necrotizing fascitis
Why is it important to know oxygen requirements of pathogens? Other microorganisms?
So you can identify/kill them
Aerotolerants grow equally well in presence or absence of O2, true or false?
What grows faster, aerotolerants or microaerophiles and why?
microaerophiles because they use oxgen which produces more energy than all other forms of metabolism
What are the 5 groups discussed in terms of oxygen requirements?
obligate aerobes, obligate anaerobes, facultatives, microaerophiles, and aerotolerants
If you grow microorganisms in agar deeps, where will different ones grow according to O2 needs?
See notes
What two things can pH extremes do to a cell?
inhibit enzyme function and disrupt cell membranes
What does the Helicobacter pylori excrete?
How does the Helicobacter pylori use urease?
It excretes it which converts the very acidic urea to ammonia (basic) which creates a pocket of ammonia that neutralizes the environment around it allowing it to survive the harsh conditions
What does k represent?
The number of generations/unit time
What does g represent?
generation time = time/generation
If you want to find the generations per unit of time, what formula would you use?
If you want to know the time/generation, what formula would you use?
g = 1/k
n can be figured out using:
log Nt - log No/log 2
What does urease do?
Breaks urea into CO2 and NH4
What does the NH4 produces by helicobactor pylori do?
Neutralizes stomach acid
How can we detect helicobactor pylori?...3 ways
Diagnostic tests such as labeled urea (breathalizers), antibody test, stomach biopsy
What are the effects of low water availability in a cell?
cell dries and metabolism stops
What is the process in which water moves out of a cell?
What do compatible solutes do and give three examples?
Raise solute concentration of cytoplasm. Ex. sugars, amino acids, potassium ions
Give an example of an osmotolerant bacteria.
Staphylococcus is an osmotolertant bacteria has blank and lives blank.
salt concentrations up to 20%, on human skin
Beneficial resident (living in you) flora characteristics include (3 things)
non-pathogenic, protectors, aid in digestion
Opportunistic resident (living in you) flora characteristics include:
living and using you, and given the opportunity, will make you sick
Organisms that use their environment vs. change their environment are called:
Give an example of a halophile
What kingdom do halobacterium belong to?
Are any archaea human pathogens?
What compatible solute do halobactria have?
What stabilizes the cell wall and membrane of Halobacterium?
In Halobacterium, K+ stabilizes:
ribosomes, enzymes, and transport proteins
What determines microbial death?
No growth when inoculated into culture medium that normally supports growth
What is sterilization?
Destroys all or removes all viable microorganisms including viruses and endospores
What is disinfection?
Reducing the numbers of pathogents to safe levels
What is antisepsis used on?
Living tissue
What is the difference between bacteriocidal and bacteriostatic?
Bacteriocidal kills, bacteriostatic keeps from growing
Give several factors influencing effectiveness?
Type of microorganism (endospores, acid-fast cells, etc), what growth stage it's in, what are you treating, population size, local environment (temp, pH, organic matter), concentration or intensity of treatment (MIC=minimum inhibitory concentration), length of exposure
What is decimal reduction time?
D-value: time required to kill 90% of the microorganisms or spores in a sample at a given temperature.
What is z-value?
The increase in temperature required to reduce D-value by 10%
In Clostridium botulinum spores D_121_= 0.204 minutes. How much time is needed at 121C to reduce a population of 10^5 C. botulinum spores to 10^0 spores (1 spore)?
Kill 90% of 100,000 (1), kill 90% of 10,000 (2), kill 90% of 1,000 (3), kill 90% of 100 (4), kill 90% of 10 (5) = 1...5 x 0.204 = 1.02 minutes
What are three things moist heat will do to cells?
degrade nucleic acids, denature proteins, and distrupt membranes
What is an autoclave and what does it do?
Steam under pressure (ex. 15 psi pressure and 121C for 15 minutes), for sterilization
If you raise the temperature one Z-value, how long will the D-value now be? D_60_ = 15.4 minutes, Z-value = 6.8C
D_60_ = 2.0 minutes, Z-value = 5.6C
D_65.6_= 1.8 minutes, this decrease D value by 10%
Who invented pasteurization and under what circumstances?
Louis Pasteur while trying to figure out how to prevent wine spoilage without changing the taste
What is the reason for pasteurizing milk?
To lower all bacteria to a non-pathogenic level.
How do you pasteurize milk?
72C for 15 seconds followed by rapie cooling
Is pasteurization a form of sterilization?
Name some bacteria that pasteurization controls?
Listeria spp, Brucella, Salmonella spp, and Mycobacterium tuberculosis
Under what conditions do you use Ultra High Temprature (UTH) sterilization?
140C for ~3 seconds
What else is pasteurized besides milk?
cheese, apple cider
What are the conditions of dry-heat sterilization?
160-170C for 2-3 hours
What does dry heat sterilization do (3 things)?
oxidizes cell components, denatures proteins, and destroys some materials
What is thermal death time?
The time necessary to kill all microorganisms in a sample at a given temperature.
What is thermal death point?
The temperature necessary to kill all microorganisms in a sample after 10 minutes.
What are the effects and limitations of low temperatures?
Slow growth, but not sterilization
Does anything still grow in the refrigerator? What?
Yes, psychrophiles
What environmental factors effect rate of growth? (4 things)
Temp, oxygen, pH, salts and sugars
Why is filtration used?
If a fluid is heat sensitive
What types of solutions is filtration used on?
Opthalmic solutions: some culture media, antibiotics, beer
How does non-ionizing radiation cause mutations?
Non-ionizing radiation such as UV light can cause thymine dimers to form (T-T to react and link to one another), resulting in poor penetration
What is nonionizing radiation used for?
usually disinfectants
What forms on ionizing radiation cause mutations? What do these mutations do?, Good or bad penetration?
gamma and x-rays, destroy DNA, good
Ionizing radiation is a form of blank? Where is ionizing radiation used?
sterilization, food and medical industries (food must be labeled)
What is triclosan?
A common antibacterial agent, a different form of sterilization
Where can you find triclosan?
Soaps, deoderants, lotions, cutting boards, toys, etc.
What is a triclosan resisant bacteria?
Pseudomonas aeruginosa
Why shouldn't you overuse triclosan?
Resistant bacteria...
Whose job is it to test effectiveness of sterilization, etc.?
US Environmental Protection Agency (EPA) and Food and Drug Administration
What does a thymine dimer do?
Disrupts the production of proteins
What is metabolism?
All of the biochemical reactions occurring in the cell
What are the Five Metabolic Tasks of a cell required to double cell mass?
Bringing nutrients into the cell, Catabolism, Biosynthesis, Polymerization, and Assembly
What is catabolism?
Breaking apart nutrients into (12)precursor metabolites, ATP, and reducing energy
What is Biosynthesis?
Synthesizing all necessary small molucules (subunits), including building blocks for macromolecules, from precursor metabolites.
What is Polymerization?
Stringing together building block subunits to make macromolecules (polymers such as DNA, proteins).
What is the Assembly step?
Assembling marcromolecules into organelles, polymers function all together to form cellular oragnelles (cell wall, membranes, ribosomes, flagella, pili)
What are substrates?
Compounds that are the starting points of a pathway or reactants of enzymes
What are metabolic intermediates?
Compounds formed by one reaction in catabolic pathways and used by subsequent reactions.
How do you say ATP? ADP?
Adenosine triphosphate, Adenosine diphosphate (monophosphate=one phosphate group)
What are the three components of ATP?
Nitrogen base, sugar, and a phosphate group
Where is the energy stored in ATP?
The bonds connecting phosphates are high energy reactive bonds (angry queens).
How is ATP formed?
From the phosphorylation of ADP
What types of processes (4) in different organisms lead to the production of ATP?
Aerobic/Anaerobic respiration, fermentation, and photosynthesis.
What three types of work are accomplished with the help of ATP?
Chemical, transport, and mechanical
ATP formation: What is substrate level-phosphorylation?
A transfer of phosphate from a metabolic intermediate.
In order to transfer a phosphate from a metabolic intermediate, what is a requiredment of the MI?
It must be high energy.
What is another word for oxidative phosphorylation? What does this process use?
Chemiosmosis. Reducing Energy.
What is oxidation?
Losing electrons
What is Reduction?
Gaining electrons.
What is reducing power used for?
Making ATP.
Reducing power removes what from what?
electrons from a substrate.
How do electrons move inside the cell?
e- + H+ --> H (hydrogen atoms)
Can H+ and e- split?
What transfers H atoms inside cells?
Oxidizing NADH results in...
Oxidizing FADH_2_ results in...
NAD+ and FAD
Reducing NAD+ and FAD results in...
NADH and FADH_2_
Which has more energy, NADH or NAD+?
NADH has a higher reducing power.
For what is energy from NADH and NAD+ used?
oxidative phosphorylation.