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29 Cards in this Set

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Microbial growth
Increase # of cells not size
Requirements for growth
Physical- Temp, pH, Osmotic Pressure

Chemical- sources of carbon, nitrogen , sulfur, phosphorus, trace elements, oxygen , and organic factors.
Psychrophiles Pref Temp
min -10 max 30 optimal 15 degrees C
Mesophiles pref temp
min 10 max 50 optimal 37
Thermophiles pref temp
min 40 max 70 optimal 60
Hyperthermophiles pref temp
min 70 max 110 optimal 95
pH mold yeast acido philes
Most bacteria grow 6.5 -7.5
Molds and yeasts grow 5-6
Acidophiles grow only in acidic enviro
Osmotic pressure
Hypertonic environments, increased salt or sugar cause plasmolysis
-cell wall protects bacteria from hypotonic enviro
-extreme or obligate halophiles require high osmotic pressure
facultative halophiles tolerate high osmotic pressure
Carbon
-structural organic molecules energy source
-heterotrophs use organic carbon sources
-autotrophs use CO2
Nitrogen
-in amino acids, proteins
-most bacteria decompose proteins
-some bacteria use NH4+ or NO3-
-a few bacteria use n2 in nitrogen fixation
Sulfur
-in amino acids and biotin
-most bacteria decompose proteins
-some bacteria use SO4^2- or H2S
Phosphorus
-In DNA RNA ATP and membranes
PO4^3- is a source of phosphorus
Trace elements
Inorganic elements required small amounts
-potassium, magnesium,calcium, iron, copper, zinc
Usually as enzyme cofactors
Organic Growth factors
organic compounds obtaines from the environment
vitamins, amino acids, purines, pyrimidines
Culture Media
Nutrients prepared for microbial growth in the lab
Sterile
No living microbes
Inoculum
Introduction of microbes into medium
Culture
Microbes growing in on culture medium
Culture medium
liquid for = broth solid gel form using agar = plates slants and deeps
Agar
Complex poly saccharide
used as solidifying agent for culture media in petri plates slants and deeps
generally not metabolized by microbes
l
Selective media
suppress unwanted microbes and encourage desired microbes.
Differential media
make it easy to distinguish colonies of different microbes
Reproduction Prokaryotes
Binary fission
Cell elongates and DNA is replicated
Cell wall and plasma membrane begin to divide
Cross wall forms completely around divided DNA
Cells separate
Phases of bacterial growth in a new culture
Lag Phase
initial period of little to no cell division
log phase
period of exponential growth with a constant generation
Stationary Phase
cell GROWTH IS EQUAL TO CELL DEATH
Death Phase
Cell death exceeds cell growth
Quantifying microbial growth -Direct measurements
Plate counts filtration most probable number direct microscopic count
Indirect Estimations
Turbidity metabolic activity dry weight