Lecture 3: Microbial Metabolism Flashcards

Question 1

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Question 2

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What do we mean by metabolism?

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Nutrition leading to energy generation & growth

Catabolism: breakdown of molecules into simple forms. Used for energy generation & supplying building blocks for growth. (Releases energy, some lost as heat)
Anabolism (biosynthesis): construction of complex molecules from simpler ones, energy requiring process

Question 3

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Growth : Anabolism

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requires energy
breaking & forming chemical bonds releases & uses energy

Question 4

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Catabolism

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generally a gradual breakdown of complex structures
electrons transferred to generate energy for the cell
microbes can be classified bases on how they generate energy e.g. chemical reactions or light

Question 5

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Energy & life

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life based on carbon (& N, S, O, H, P etc.)
energy acquisition by cells is linked to biosynthesis (but is separate)
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Question 6

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Organisms can be described by how they obtain energy & carbon

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Helps to understand:
- the role & effect organism has in habitat
- requirements needed for growth & colonisation
- ultimately how ecosystems function

Question 7

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Definitions:

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energy

if microbe generates energy from light: Phototroph
if microbe generates energy from chemical rearrangement of molecules (organic or inorganic): Chemotroph

Question 8

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Definitions:

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*growth**:
- if microbe fixes CO2 as a principal carbon source = Autotroph
- if microbe uses external sources of carbon for biosynthesis = Heterotroph

Mixotroph can do both

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Definitions

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Definitions:

Question 11

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Definitions:

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chemotrophs can use organic or inorganic sources
organotroph: microbe uses chemical pathways using organic molecules to donate electrons to generate energy, (often used synonymously with CHEMOHETERTROPH)
Lithotroph: microbe uses chemical pathways using inorganic molecules to donate electrons to generate energy
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Question 12

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Question 13

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Energy & microbial communities

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understanding metabolic processes helps understand ecosystem functions
elements must be cycled between species to allow growth (all food webs)
interdependence between groups of organisms key to survival
E.g. without autotrophy, heterotrophy would convert all C in biomass to CO2 in years

Question 14

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Question 15

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Energy & microbial communities

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Microbial communities are highly competitive
- compete for resources > directly & indirectly
- survival depends on ability to utilise available resource
> niche partitioning
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Question 16

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KEY MESSAGE

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The metabolism / chemical reaction that generates the greatest amount of energy in a given environment will be favoured

Question 17

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Question 18

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All about energy

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C6H12O6 + 6O2&raquo_space;> 6CO2 + 6H2O
Oxidation of glucose generates energy for the cell.
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Question 19

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Oxidation-reduction reactions (REDOX)

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movement of an electron from a molecule (oxidation) to another (reduction) - OIL RIG
some redox reactions carried out by microbes:

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Question 20

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Energy defined by thermodynamic laws

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1) in energy transformations, the total energy remains constant (i.e. energy is not created or destroyed)
2) in energy transformations, some energy creates a disorder (entropy) & not work (i.e. systems tend to become more disordered)
3) entropy becomes constant as temp approaches absolute 0

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Question 21

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All about energy

Question 22

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Energy defined by thermodynamic law

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Total energy of a system = Enthalpy (H)
H = G + T x S

G = free energy; T = temperature; S = entropy (disorder) = unusable energy

Question 23

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Gibbs Free Energy Change, ΔG

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ΔG = ΔH - TΔS

ΔH = heat transfer released or absorbed (enthalpy)
ΔS = measure of disorder (change in entropy)
T = temp
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Question 24

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Gibbs Free Energy Change, ΔG

Question 25

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