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38 Cards in this Set

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Exercise 19:

What does the cultivation of microorganisms on an artificial growth medium require?
Requires that the medium supply anll the nutritional and energy requirements necessary for growth.
Exercise 19:

What is a complex medium?
A medium using rich extracts of meat or plants that would supply all the amino acids, nucleotide bases, vitamins and other growth factors; most medium is complex.
Exercise 19:

Why is it referred to as complex?
Because the exact composition and amounts of the individual amino acids, vitamins, growth factors and other components that make up the medium are not exactly known.
Exercise 19:

What is a defined medium?
A medium where the specific chemical components are known and the individual components are weighed out exactly to make the medium.
Exercise 19:

What are the basic nutritional requirements of bateria?
carbon source, energy source, nitrogen, minerals, vitamins and growth factors, and water.
Exercise 19: carbon source
-Organisms can be divided into 2 groups based on their carbon requirements, what is one of the groups?
Heterotrophs: get carbon from organic compounds like polysac, carbs, a.a, peptides & protein; meat and plants extracts must be added to complex media to supply these nutrients.
Exercise 19: carbon source
-Besides heterotrophs, name the other group of organisms:
Autotrophs: get carbon by fixing carbon dioxide; must sythesize all complex molecules that make the bacterial cell.
Exercise 19: energy source

-Define chemotroph
Organisms that get their energy from the breakdown of organic molecules by fermentation or respiration; most bacteria belong to this group.
Exercise 19: energy source

-Define Chemolithotrophs
Organisms that oxidize inorganic ions such as nitrate or iron to obtain energy; include nitrifying and and iron bacteria.
Exercise 19: energy source

-Define Photoautotrophs
Organisms that contain photosynthetic pigments such as chlorophyll or bacteriochlorophyll that convert solar energy into chemical energy via photosyn.; no energy source in medium except light; eg. cyano, green and sulfur bacteria.
Exercise 19: energy source

-Define Photoheterotrophs
Organisms that get their energy from photosynthesis, but their carbon from growth on organic molecules like succinate or glutamate; not many bacteria but some purple nonsulfur.
Exercise 19: energy source

-What's the difference b/w photoautotrophs and photoheterotrophs?
-Photoautotrophs use their energy to fix CO2, for their carbon, while photoheterotrophs get their carbon needs from organic molecules.
Exercise 19: nitrogen
-How do bacteria get their N?
Some synthesize it, some gain it via organic molecules, others can fix atmospheric N like the bacteria Rhizobium and Azotobacter.
Exercise 19: Minerals

-Why are they so important for bacteria>
B/c metals are req. in bacterial metabolism as they are cofactors in enzymatic reactions and are integral parts of molecules like cytochromes;
Exercise 19: Minerals

-What metals are required for growth?
Sodium, potassium, calcium, magnesium, maganese, iron, zinc, copper, cobalt and phosphorous.
Exercise 19: Vitamins & Growth Factors
-What do you need to add to the medium for these?
Blood and serum.
Exercise 19: Vitamins & growth Factors

-What do vitamins do for the bacteria?
Serve as coenymes, eg. the vit niacin is part of the coenzyme NAD; some bacteria req vits b/c they can't synthesize them, others can, but its nec. to add growth factors for AMPLE growth of certain bacteria, like pathogens.
Exercise 19: Water

-why do cells require an aqueous environment?
Cells consist 70-80% of water; need aq. environ. b/c enzymatic reactions and transport only occur in the presence of water; (h20 also maintains copmonents in the cytoplasma)
Exercise 19: Water

-Why do we need to use distilled water when preparing medias?
B/C tap water can contain minerals like calcium that could react with the peptones and meat extracts to cause unwanted precipitates and cloudiness.
Exercise 19:

-What id a selective medium?
Media made with components (like antibiotics, dyes) that will allow certain bacteria to grow but will inhibit others from growing
Exercise 19:

-What is differential medium?
Contains substances that cause some bacteria to take on an appearance that distinguishes them from other bacteria, eg: Staphylococcus aureus
Exercise 19:

-What is agar?
A complex polysaccharide from sea weed, added to liquid media to solidify it; first used in Koch's lab; melts at 100*C and solidifies at 45*C (temp that bacteria can be innoculated @ w/o killing cells
Exercise 19:

-what do you add to media if the pH is too high?
HCL
Exercise 19:

-what do you add to media if the pH is too low?
NaOh
Exercise 19:

-When filling the test tubes with agar, what do you need to make sure you do to maintain the agar in solution?
Keep the medium on a stirring hot plate, usually a magnetic stirrer is used.
Exercise 19:

-When medium is to be used for fermentation, what do you need to add to the test tube?
You need to add a Durham tube, open end down, BEFORE adding the medium.
Exercise 19:

-Why do we use an autoclave for sterilization?
B/C it can achieve the complete sterilization temperature of 250*C, by developing 15lbs/square inch of steam.
Exercise 21:

-How are bacteria classified?
Based on their requirement for air that contains 20% oxygen.
Exercise 21:

-What are Obligate Strict Aerobes?
Organisms that require oxygen for growth - primarily carry out respiratory metabolism where oxygen acts as a terminal electron acceptor.
Exercise 21:

-What are Obligate Strict Anaerobes
Bacteria that can't tolerate oxygen; carry out fermentation aka anaerobic respiration for growth; sensitivity is to the by products of oxygen like peroxide.
Exercise 21:

-what is the diff b/w aerobes and anaerobes?
Aerobic bacteria have enzyme systems that convert O2 by products so that they don't destroy their cells, anaerobes lack these enzymnes.
Exercise 21:

-what is a facultative anaerobe?
bacteria that can grow by respiratory means if O2 is present, if there's no )2 can grow via fermentation, eg. E.coli
Exercise 21:

-what are microaerophiles?
organisms that require O2 on amounts lower that the atmosphere; growth can be done in a candle jar
Exercise 21:

-what are aerotolerant bacteria?
Bacteria that can grow in O2, but that don't use it as terminal electron acceptor, hence they are indifferent to the presence of O2; carry out fermentation; grow better with little O2, eg. Streptococcus
Exercise 21:

-What's a TGYA shake?
A solid medium used to prepare shake tubes to det the O2 req of diff. bacteria
Exercise 21:

-What's FTM?
Fluid thioglycollate medium is a rich liquid medium that supports the browth of aerobic and anaerobic bacteria; conatins resazurin dye that turns pink when there's O2.
Exercise 21:

-What is Brewer's Anaerobic agar?
A solid medium used for culturing anaerobic bacteria in petri dishes, contains thioglycollate, a reducer and resazuirn O/R reducer
Exercise 21:

-How do you incubate anaerboic bacteria in an O2 free environment?
In FasPak anaerobic jars, where hydrogen is generated to remove the oxygen by forming water; palladium pellets catalyze the reaction at room temperature; indicator strip of methblue used, will be colorless if no O2.