Lecture 3: Microbial Growth and Nutrition

Question 1

_______:
* 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

Answer 1

Macronutrients

Question 2

_____–C,H,O,N(andS)
* Polymer of made of building blocks – amino acids
* > 50% of cell dry weight

Answer 2

Protein

Question 3

______–C,H,O(andP)
* Building blocks = fatty acids and glycerol
* Ex) Phospholipids

Answer 3

Lipids

Question 4

_______ – C, H, O (and N)
* Building blocks = sugars
* Ex. Polysaccharides and peptidoglycan

Answer 4

Carbohydrates

Question 5

_________ – C, H, O, N, P
* Building blocks = nucleotides
* Ex. DNA and RNA

Answer 5

Nucleic acids

Question 6

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+

Answer 6

inorganic ions

Question 7

_____ helps stabilize membranes and nucleic acids

____ helps stabilize cell walls, and plays a role in heat stability of
endospores

Answer 7

Mg2+
Ca2+

Question 8

T/F: All of the macronutrients should be considered when making media

Answer 8

true!

Question 9

_______:
* 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

Answer 9

Micronutrients

Question 10

———
* 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

Answer 10

Growth factors

Question 11

what are the three classes of growth factors?

Answer 11

amino acids, purines and pyrimidines, vitamins

Question 12

which bacteria requires no growth factors?

Answer 12

E. coli

Question 13

T/F: Addition of growth factors to medium
may promote growth

Answer 13

true!

Question 14

_____:
* No specific nutrient
* Found in H2O and organic media components

Answer 14

H, O

Question 15

_______:
* Usually provided as phosphate salt (PO4
3-)
* Ex) K2HPO4, KH2PO4

Answer 15

P

Question 16

why is phosphate given as phosphate salt? (PO4 3-)

Answer 16

because that’s how its usually acquired in the environment, in freshwater systems PO4 3- is often limiting

Question 17

________
* In relatively low concentration compared to other nutrients
* When it runs out, growth stops despite other nutrients present

Answer 17

Limiting nutrient

Question 18

which nutrient has many possible sources? (3) what are they?

Answer 18

Nitrogen

Inorganic N
Organic N
Atmospheric N

Question 19

_______
* Provided as salts (ex. KNO3 or NH4Cl)
* Must be reduced to NH3– used to make amino acids (-NH2)

Answer 19

Inorganic N

Question 20

_______
* Provided as N rich organic molecules (ex. Amino acids or short peptides) -
does not need to be reduced

Answer 20

Organic N

Question 21

———
* 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

Answer 21

Atmospheric N2

Question 22

what are the two possible forms of sulfate (S)?

Answer 22

inorganic S
organic S

Question 23

________
* Provided as salts (ex. MgSO4)
* Must be reduced to the level of S2- used to make amino acids
* Assimilative sulfate reduction

Answer 23

Inorganic S

Question 24

_______:
* Pre-made amino acids (cysteine and methionine)
* Less energy to assimilate

Answer 24

Organic S

Question 25

Organisms placed into 2 groups based on how they obtain C, what are they?

Answer 25

heterotrophs and autotrophs

Question 26

_______
* 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

Answer 26

Heterotrophs

Question 27

________
* Use inorganic carbon (CO2) as their sole source of carbon
* Requires energy to assimilate
* Photosynthesis

Answer 27

Autotrophs

Question 28

what are the three classes of culture media?

Answer 28

defined medium
minimal medium
complex medium

Question 29

_______:
* Exact chemical composition is known
* Useful for studying metabolism

Answer 29

Defined medium

Question 30

_______:
* A defined medium that provides the
minimum nutritional requirements for growth
(ie. No growth factors)

Answer 30

Minimal medium

Question 31

________:
* 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

Answer 31

Complex medium

Question 32

_______:
* 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

Answer 32

Differential medium

Question 33

______:
* 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

Answer 33

Selective medium

Question 34

________:
* Supplemented with special nutrients to encourage the
growth of fastidious bacteria
* Complex nutrient requirements – require many
growth factors
* Ex) Blood agar, chocolate agar

Answer 34

Enriched medium

Question 35

______:
* The sum total of all of the chemical reactions that occur in a cell

Answer 35

Metabolism

Question 36

_______:
* Energy-releasing metabolic reactions (e.g. fermentation, respiration)

Answer 36

Catabolic reactions (catabolism)

Question 37

_______:
* Energy-requiring metabolic reactions (biosynthesis)

Answer 37

Anabolic reactions (anabolism)

Question 38

Microorganisms grouped into energy classes depending on their source of electrons and energy, what are the three classes?

Answer 38

chemorganotrophs
chemolithotrophs
phototrophs

Question 39

_______:
* Energy from chemical reactions involving
organic material

Answer 39

Chemorganotrophs

Question 40

_______:
* Energy from inorganic chemical reactions

Answer 40

Chemolithotrophs

Question 41

_______:
* Energy from light

Answer 41

Phototrophs

Question 42

Microorganisms can be grouped with respect to carbon source, what are the two groups?

Answer 42

heterotrophs and autotrophs

Question 43

_______:
* Use organic carbon for building cell carbon
and biomass

Answer 43

Heterotrophs

Question 44

_______:
* Use CO2 to synthesize cell carbon
* a.k.a. primary producers

Answer 44

Autotrophs