Lecture 3: Microbial Growth and Nutrition Flashcards
_______:
* Elements required in large amounts to build macromolecules
* The building blocks of cell material
* C,H,O,N,P and S makeup
over 90% of the dry weight of the cell
Macronutrients
_____–C,H,O,N(andS)
* Polymer of made of building blocks – amino acids
* > 50% of cell dry weight
Protein
______–C,H,O(andP)
* Building blocks = fatty acids and glycerol
* Ex) Phospholipids
Lipids
_______ – C, H, O (and N)
* Building blocks = sugars
* Ex. Polysaccharides and peptidoglycan
Carbohydrates
_________ – C, H, O, N, P
* Building blocks = nucleotides
* Ex. DNA and RNA
Nucleic acids
Other Macronutrients – _________ (K, Mg, Ca, Fe)
* Often serve as metabolic co-factors
* Non-protein component required for enzyme function
* Enzymes involved in protein synthesis require K+
* Cytochromes (e- carriers) require Fe2+
inorganic ions
_____ helps stabilize membranes and nucleic acids
____ helps stabilize cell walls, and plays a role in heat stability of
endospores
Mg2+
Ca2+
T/F: All of the macronutrients should be considered when making media
true!
_______:
* Elements required in very small amounts (trace elements)
* Usually serve as cofactors for enzymes
* Ex) Mn, Zn, Co, Ni, Cu, Mo
* Se is required to make the unusual amino acid selenocysteine
Micronutrients
———
* Small organic molecules required for growth
* If an organism cannot synthesize the _______, then it must be added to
medium to grow that microbe in the lab
Growth factors
what are the three classes of growth factors?
amino acids, purines and pyrimidines, vitamins
which bacteria requires no growth factors?
E. coli
T/F: Addition of growth factors to medium
may promote growth
true!
_____:
* No specific nutrient
* Found in H2O and organic media components
H, O
_______:
* Usually provided as phosphate salt (PO4
3-)
* Ex) K2HPO4, KH2PO4
P
why is phosphate given as phosphate salt? (PO4 3-)
because that’s how its usually acquired in the environment, in freshwater systems PO4 3- is often limiting
________
* In relatively low concentration compared to other nutrients
* When it runs out, growth stops despite other nutrients present
Limiting nutrient
which nutrient has many possible sources? (3) what are they?
Nitrogen
Inorganic N
Organic N
Atmospheric N
_______
* Provided as salts (ex. KNO3 or NH4Cl)
* Must be reduced to NH3– used to make amino acids (-NH2)
Inorganic N
_______
* Provided as N rich organic molecules (ex. Amino acids or short peptides) -
does not need to be reduced
Organic N
———
* N2 is reduced to 2NH3– Nitrogen fixation
* NH3 is used to make amino acids
* Energetically expensive
* Can only be done by some Bacteria and Archaea – not by eukaryotes
Atmospheric N2
what are the two possible forms of sulfate (S)?
inorganic S
organic S
________
* Provided as salts (ex. MgSO4)
* Must be reduced to the level of S2- used to make amino acids
* Assimilative sulfate reduction
Inorganic S
_______:
* Pre-made amino acids (cysteine and methionine)
* Less energy to assimilate
Organic S
Organisms placed into 2 groups based on how they obtain C, what are they?
heterotrophs and autotrophs
_______
* Use organic carbon
* One or more C is reduced (ie. a C atom with one or more H’s)
* Ex) Organic acids, alcohols, carbohydrates, amino acids
Heterotrophs
________
* Use inorganic carbon (CO2) as their sole source of carbon
* Requires energy to assimilate
* Photosynthesis
Autotrophs
what are the three classes of culture media?
defined medium
minimal medium
complex medium
_______:
* Exact chemical composition is known
* Useful for studying metabolism
Defined medium
_______:
* A defined medium that provides the
minimum nutritional requirements for growth
(ie. No growth factors)
Minimal medium
________:
* Exact chemical composition is not known
* Often made from meat or yeast extracts
* Supply a variety of growth factors
* Ex) T-soy broth and plates
Complex medium
_______:
* Allows different bacteria to be distinguished
* Ex) Blood agar – T-soy plate + 5% sheep’s blood
* Allows differentiation of hemolytic bacteria
* a– incomplete destruction of blood cells
* b– complete destruction
* g– no destruction
Differential medium
______:
* Contain ingredients that inhibit the growth of
unwanted microbes
* Allow only specific microbes to grow
* Ex) Mannitol salt agar
* Contains very high salt, so that only halotolerant
bacteria will grow
* Used to isolate staphylococci from skin
Selective medium
________:
* Supplemented with special nutrients to encourage the
growth of fastidious bacteria
* Complex nutrient requirements – require many
growth factors
* Ex) Blood agar, chocolate agar
Enriched medium
______:
* The sum total of all of the chemical reactions that occur in a cell
Metabolism
_______:
* Energy-releasing metabolic reactions (e.g. fermentation, respiration)
Catabolic reactions (catabolism)
_______:
* Energy-requiring metabolic reactions (biosynthesis)
Anabolic reactions (anabolism)
Microorganisms grouped into energy classes depending on their source of electrons and energy, what are the three classes?
chemorganotrophs
chemolithotrophs
phototrophs
_______:
* Energy from chemical reactions involving
organic material
Chemorganotrophs
_______:
* Energy from inorganic chemical reactions
Chemolithotrophs
_______:
* Energy from light
Phototrophs
Microorganisms can be grouped with respect to carbon source, what are the two groups?
heterotrophs and autotrophs
_______:
* Use organic carbon for building cell carbon
and biomass
Heterotrophs
_______:
* Use CO2 to synthesize cell carbon
* a.k.a. primary producers
Autotrophs
