Microbial Growth and Nutrition- PT 1 Test 1 Flashcards
supply of elements required by cells for growth
nutrients
nutrients required in large amounts
macronutrients
nutrients required in small amounts trace metals and growth factors
micronutrients
What six elements does every organism need?
water, carbon, oxygen, hydrogen, nitrogen, phosphorous, sulfur
What are the major macro molecules in the cell?
carbs, proteins, lipids, nucleic acids
-must contain all the nutrients required by the organism for growth
-classification of physical nature, chemical constituents from which they are made, function
culture media
exact chemical composition known
defined media
composed of digests of microbial animal or plant products
complex media
contains compounds that selectively inhibit growth of some microbes but not others
selective medium
contains an indicator, usually a dye, that detects specific metabolic reactions during growth
differential medium
What are the solidifying agents commonly used?
-gelatin, starch, agar
-complex polysaccharide isolated from red algae
-solid at room temp liquefies at boiling cools and solidifies at 42 degrees Celsius
-provides framework
-not digestible for most microbes
agar
-microscopic cell count- observing and enumerating cells present
-dried on slides or on liquid samples
-counting chamber with squares etched on a slide used for liquid samples
-you do not know if they are alive or dead
-hard to have accurate precision
-not consistent
-can have broken cells
total cell count
What are the different growth phases?
-lag- introducing bacteria
-exponential- binary fission
-stationary- balance of chilling and reproducing
-decline- some level where there may not be enough nutrients
What are the steps of binary fission?
-cell elongates and DNA is replicated
-cell wall and plasma membrane begin to constrict
-cross-wall forms completely separating the two DNA copies
-cells separate
What is the symbol for generation time?
g
What is the symbol for time?
t
What is the symbol for cell number at time?
Nt
What is the symbol for starting cell number?
N0
What is the symbol for number of generations?
n
What is the symbol for specific growth rate?
k
Psychrophilic
like it cold, they wont grow well past 10 degrees
mesophile
broad range, thrive at body temp
thermophile
high temp
Hyperthermophile
really high temp
Optimal ph refers to what?
extracellular only
The intracellular ph must stay relatively close to neutral consistent with what?
macromolecule stability
Microbial culture typically contains buffers to maintain what?
constant ph
-what causes plasmolysis because of hypertonic environments, required by extreme or obligate halophiles, and tolerated by facultative halophiles
high osmotic pressure
grows very well in high salt concentrations
halophile
can grow with salt but does not have to
halotolerant
not much salt at all
nonhalotolerant
can grow when osmotic concentrations are really high
osmophile
can grow really well when dry
zerophile
What are the enzymes that destroy toxic oxygen species like superoxide, hydrogen peroxide, and hydroxyl radical?
catalase, peroxidase, superoxide dismutase, combination of catalase and superoxide dismutase, and superoxide reductase
oligate aerobe
requires oxygen
facultative aerobe
not required but grows better with oxygen
microaerophilic aerobe
required but at levels lower than atmospheric
aerotolerant anaerobe
not required and grows no better with oxygen present
obligate anaerobe
harmful or lethal
