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27 Cards in this Set

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What is the average generation time for bacteria?
Average generation time for bacteria is 20 minutes – that means the cell population will double every twenty minutes.
Bacterial cells divide by means of Binary Fission- Summarize the steps.
What happens to growth synthesis once glucose is exhausted?
Bacterial growth that have conditions other than optimum are?
Bacteriostatic

Conditions other than optimum are bacteriostatic
Define Bactericidal
Bactericidal

Conditions beyond minimum or maximum are bactericidal - growth cannot occur
Summarize minimum optimum and maximum growth rates.
Define OSMOSIS.
Osmosis: net movement of water from a solution of lesser solute concentration to one of greater solute concentration across a membrane which is more permeable to water than to the solute molecules
Describe a hypotonic cell.
Summarize Hypertonic cells.
Summarize isotonic cells/conditions.
Which cells are very subceptible to Lysozyme – digests disaccharide in peptidoglycan and Penicillin – inhibits synthesis of peptidoglycan?
G + cells because of the inhibition of peptidoglycen ruptures the cell since structural integrity is compromised.
Summarize the optimum temperatures of the following Psychrophiles, psychotrophs, mesophiles, thermophiles, hyperthermophiles.
Which type of bacteria prefer human factors for optimum conditions for growth?
mesophiles @ 25-40 degrees
Summarize the zones of bacterial growth in food from negative 30 to 130 degrees celsius.
Which type of organisms grow in the optimum conditions of a refrigerator.
Psychrotrophs: common spoilage organisms; grow at refrigerator temperatures
Bacteria are classified by their oxygen reaction: required, tolerated or toxic. Summarize Aerobes, Anaerobes, and Aerobes.
Summarize Molecular Oxygen and why they are dangerous to cells.
Molecular oxygen (O2) is highly reactive & toxic to cells
Cells must possess detoxifying enzymes to neutralize the free radicals

O2- + 2H+ ----SOD---> H2O2
superoxide dismutase

H202 = Hydrogen Peroxide
What enzymes do cells utilize to neutralize Hydrogen Peroxide (H202)?
What is In Vitro?
In vitro Cultivation of Bacteria
Summarize Medium and its varietes.
Medium starts sterile. The Medium is used to help cultivate growth in bacterium.

1) Complex medium (NA or NB) = extracts of yeasts, meat, or plants and essential nutrients; additional growth factors added as per species

2) Selective medium
Vary pH, salinity, nutrients, etc.

3) Differential medium
Due to differential uptake of dyes
Summarize Inoculum.
Inoculum: microbes intentionally introduced into medium and thus inocculated.
What is Biosynthetic capacity?
Biosynthetic capacity of the species and purpose for cultivation determines the medium used or how well a bacteria self sufficiently provides for itself.
Summarize incubation.
Incubation: period of growth under controlled conditions

Temperature

Atmosphere
What is a pure culture?
Pure culture:
contains only one species or strain
every cell is descended from a single CFU


Colony or colony forming unit (CFU):
population of cells arising from a single cell
What is confluent growth?
Growth usually found on a plate that has several clusters of bacteria that occurs in the 1st and 2nd streak in order to isolate colonies.
What number do scientists determine to be statistically reliable and countable plates (in CFU's)?
if a plate contains around 30-300 isolated colonies then scientists consider that to be
Statistically reliable and countable plates: 30-300 CFUs
How can you determine a rough count of the orginal inoculum when counting isolated colonies?
1) Count the number of isolated colonies.
2) Factor in the ratio of dilution

i.e. if ratio of dilution was 1:1000 and you counted 200 colonoies. Multiply 200 X 1000 = a rough estimate of original inoculum

(please clarify this method with Dr.Bloom)