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MBIO1010 > Lecture Set 3 : Part 1 > Flashcards

Lecture Set 3 : Part 1 Flashcards

1
Q

what are macronutrients?

A

-elements required in large amounts to build macromolecules
-macromolecules are the building blocks of cell material

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2
Q

what are the “big 6” macronutrients?

A

-C
-H
-O
-N
-P
-S
-these makeup greater than 90% of the cells dry weight (makeup major cell components)

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3
Q

what are the 4 major macromolecules made from the big 6?

A

-proteins
-lipids
-carbohydrates
-nucleic acids

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4
Q

what macronutrients make up proteins?

A

-C, H, O, N, (S)
-S is present in 2 amino acids
-protein is a polymer made up of building blocks (amino acids)
-makeup greater than 50% of a cells dry weight

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5
Q

what 2 amino acids contain S?

A

-cysteine
-methionine

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6
Q

what macronutrients make up lipids?

A

-C, H, O, (P)
-P is present in phospholipids
-building blocks are fatty acids and glycerol

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7
Q

what macronutrients make up carbohydrates?

A

-C, H, O, (N)
-N is present in peptidoglycan sugars
-building blocks are sugars (monosaccharides)
-ex: polysaccharides + peptidoglycan

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8
Q

what macronutrients make up nucleic acids?

A

-C, H, O, N, P
-building blocks are nucleotides
-ex: DNA and RNA

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9
Q

what are the other 4 macronutrients? what do they serve as typically?

A

-K, Mg, Ca, Fe
-often serve as metabolic co-factors contained in the active site of an enzyme

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10
Q

what are cofactors?

A

-non-protein components required for some enzymes function

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11
Q

what are 2 examples of macronutrients acting as metabolic cofactors?

A

-enzymes involved in protein synthesis require K+
-cytochromes (e- carriers) in the electron transport chain require Fe2+

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12
Q

what are 2 other examples of functions of macronutrients?

A

-Mg2+ helps to stabilize membranes and nucleic acids
-Ca2+ helps to stabilize cell walls and plays a role in heat stability of endospores

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13
Q

what macronutrients should be considered when making media?

A

-ALL OF THEM
-all must be present for growth unless the bacteria can get them a different way

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14
Q

what are micronutrients?

A

-elements required in a very small amount (trace metals)
-typically serve as cofactors for enzymes (in the active site)

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15
Q

what micronutrients should be considered when making media?

A

-NONE
-unless the bacteria has a specific need for it
-chemical impurities can usually take care of this need

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16
Q

what are growth factors?

A

-small organic molecules required for growth of some organisms (required if they do not have the metabolic ability to make the substance themselves and therefore must be added to grow them in the lab)
-3 classes

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17
Q

what are the 3 classes of growth factors?

A

-amino acids
-purines and pyrimidines
-vitamins

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18
Q

why are amino acids an important growth factor?

A

-required for protein synthesis (20 needed)

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19
Q

why are purines and pyrimidines an important growth factor?

A

-needed to make nucleotides (building blocks of DNA and RNA)

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20
Q

what are the purines and pyrimidines?

A

-adenine + guanine (purines, 2 C-rings)
-thymine + cytosine + uracil (pyrimidines, 1 C-ring)
-uracil in RNA (replaces thymine)

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21
Q

why are vitamins an important growth factor?

A

-small molecules used to make organic cofactors
-ex: nicotinic acid (for use by NAD+)

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22
Q

what is an example of a bacteria that has no growth factor requirement?

A

-E.coli
-addition of growth factors may promote its growth but it does not require it

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23
Q

what is an example of a bacteria that requires many growth factors?

A

-leuconostoc mesenteroides
-requires all 20 amino acids, 4 purines and pyrimidines, and 10 different vitamins

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24
Q

what are sources of H and O for bacteria?

A

-no specific nutrient
-found in H2O and organic media components

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25
what are sources of P for bacteria?
-usually provides as a phosphate salt -ex: K2PO4, KH2PO4
26
why is P usually provided as a phosphate salt?
-usually acquired as PO4 in the environment
27
in what environments is PO4 a limiting nutrient?
-freshwater systems
28
what is a limiting nutrient?
-a nutrient in relatively low concentrations compared to other nutrients
29
what happens when a limiting nutrient runs out?
-growth will stop despite the other nutrients present
30
what are the 3 possible sources of N? what decides the source?
-inorganic N -organic N -atmospheric N -bacteria has a preference of sources
31
what are the sources of inorganic N?
-provided as salts -ex: KNO3 or NH4Cl -must be reduced to NH3 -is then used to make amino acids and can be put into NH2 -more work
32
what are the sources of organic N?
-provided as N rich organic molecules -ex: amino acids or short peptides -does not need to be reduced -less work
33
how is atmospheric N used?
-through nitrogen fixation (turning nitrogen gas into a useable form) -fixes it into NH3 to make amino acids -energetically expensive -can only be done by some bacteria and archaea (AND one line of algae (eukaryote) that have the nitroplast)
34
what are the 2 possible sources of S?
-inorganic S -organic S
35
what are the sources of inorganic S?
-provided as salts -ex: MgSO4 -must be reduced to the S2- ion to make amino acids (assimilative sulfate reduction)
36
when is assimilative sulfate reduction done?
-only for the purpose of obtaining S2- to make cell materials
37
what are the sources of organic S?
-pre-made amino acids (cysteine + methionine) -less energy to assimilate because it is already in a good form (amino acids are growth factors)
38
how is the source of C for an organism decided?
-placed into one of two groups that refers to the source of where the majority of C in macromolecules comes from
39
what are the 2 groups that identify how organims obtain C?
-heterotrophs -autotrophs
40
how do heterotrophs obtain C?
-use organic carbon -organic carbon = one or more C is reduced (C-H bonds present) -ex: organic acids, alcohols, carbohydrates, and amino acids
41
how do autotrophs obtain C?
-use inorganic carbon (CO2) as their sole source of carbon -requires energy to assimilate (done through photosynthesis)
42
what is an example of an autotroph bacteria?
-anabena -filamentous cyanobacteria
43
what is the first level of classes of culture media?
-defined -complex
44
what is a defined medium?
-exact chemical composition is known -useful for studying metabolism -allows for lots of control (useful for experiments where something specific is being studied)
45
what can a defined medium also be classified as?
-minimal medium
46
what is a minimal medium?
-defined medium that provides the minimum nutritional requirements for growth (ex: no growth factors) -components of this can vary for each species depending on their specific needs
47
what is a complex medium?
-exact chemical composition is not known -often made from meat or yeast extracts -ex: T-soy broth or plates -still has precision (just do not know the elemental amounts)
48
why would we use a complex medium instead of a defined medium?
-do not always know what we are growing -so we dont need to spend time satisfying specific requirements when we dont know what we need
49
what are the minimum requirements for a complex medium?
-water and yeast extract -yeast extract contains everything needed (CHOPKNSCaFeMg) since it grows yeast cells (has growth factors as well) -glucose, peptone, etc are also typically added but are not necessarily needed
50
what is a differential medium?
-a medium that allows different bacteria to be distinguished
51
what is an example of a differential medium? what could this also be classified as?
-blood agar -t soy + 5% sheep's blood -allows for the differentiation of hemolytic bacteria (ability to engage in hemolysis) -can also be classified as complex (due to the addition of sheep's blood)
52
what are the different possible results of a blood agar plate?
-alpha hemolysis - incomplete destruction of blood cells (produces a green colour, slight showing of t soy colour) -beta hemolysis - complete destruction of blood cells (produces a yellow colour, bursted blood cells reveals the t soy) -gamma hemolysis - no destruction
53
what is a selective medium? what can it also be classified as?
-medium containing ingredients that inhibit the growth of unwanted microbes -selects for a certain population to grow -used if you know exactly what you are looking for -can also be a differential medium (as well as complex or defined)
54
what is an example of a selective medium?
-mannitol salt agar -contains very high NaCl, [7.5%] (selective aspect) -only halotolerant bacteria will grow (can survive in high salt []) -mannitol is the differential aspect -bacteria that can ferment mannitol will change the plate from red to yellow
55
what is mannitol salt agar often used for?
-used to isolate staphylocooci (staphylcoccus genus) from skin
56
what is an enriched medium?
-medium supplemented with special nutrients to encourage the growth of fastidious bacteria -helps to culture pathogenic bacteria (blood agar is used to culture medically important human pathogens) -ex: blood agar, chocolate agar (cooked blood)
57
what is fastidious bacteria?
-bacteria with complex nutrient needs -they require many growth factors -ex: leuconostoc mesenteroides
58
can you grow a pure culture with a selective medium?
-not guaranteed -would need to use another medium once you find what you are looking for
59
what are the energy classes of microorganisms?
-groups based on how organims obtain their energy and electrons for anabolism and their source of carbon for cell material
60
what are the classes for the overall source of energy of microorganisms?
-chemotroph = obtains energy from chemical reactions -phototroph = obtains energy from sunlight
61
what are the classes for the source of electrons of microorganisms?
-organotroph = electrons come from already reduced organic molecules -lithotroph = electrons come from reduced inorganic molecules (commonly H2 and H2S)
62
what are the classes for the source of carbon of microorganisms?
-heterotroph = carbon comes from pre-existing organic molecules -autotroph = carbon comes from inorganic CO2
63
what organisms are chemoorganoheterotrophs? what do they engage in typically? what can some microbes do in the absence of oxygen?
-all animals, fungi, and protozoa (plus many bacteria) -engage in aerobic respiration (glucose donates electrons and oxygen accepts electrons) -some microbes can consume organic material in the absence of oxygen (fermentation + anaerobic respiration)
64
what are 2 examples of a photolithoautotroph?
-ex: cyanobacteria (and chloroplasts of green plants) -do oxygenic photosynthesis -ex: purple sulfur bacteria -can carry out photosynthesis without generating O2 -use H2S or S^0 as a source of electrons (anoxygenic photosynthesis)
65
what is an example of a photoorganoheterotroph?
-purple non-sulfur bacteria -use light energy to assimilate low energy organic acids which are waste products of other organisms
66
what do chemolithoautotrophs use H2 and H2S for?
-hydrogen oxidation (many bacteria and archaea) -2H2 + O2 > 2H2O -sulfide oxidation (some bacteria and archaea) -H2S + 2O2 > H2SO4 -methanogenesis (only methanogenic archaea, methanogens) -4H2 + CO2 > CH4 + 2H2O

MBIO1010 (28 decks)

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