L3 microbial metabolism Flashcards
What is meant by metabolism
Chemical reactions that occur within the cell to maintain normal functioning and growth
Mediated by enzymes and fuelled by the input of energy by nutrition
What can microbes use as nutrition
Wood, humans, water, metal etc.
What is catabolism
What is catabolism used for
Breakdown of molecules into simple forms
Used for energy generation and supplying building blocks for growth
What is anabolism
Does it require energy
= biosynthesis = construction of complex molecules from simpler ones
Energy requiring
Does catabolism occur quickly or slowly and why
Gradual breakdown, if broken down too quickly then massice release of energy occurs which can be harmful
What are the key atomic nutrients for life
C, N, S, O, H, P
What 2 things are used to describe organisms (microbes)
How they obtain energy and carbon
What is a phototroph
A microbe that generates energy from light
What is a chemotroph
A microbe generating energy from the chemical arrangement of molecules (organic or inorganic)
What is the name for a microbe which fixes carbon dioxide as its principal carbon source
Autotroph
What is the name for a microbe which uses external (organic) sources of carbon for biosnythesis
Heterotroph
What is a mixotroph
Able to carry out both autotrophy and heterotrophy
Can fix carbon from both carbon dioxide and organic sources
What is a photoautotroph
Give an example
Uses light and carbon diocide
Photosynthetic cyanobacteria
What is a photoheterotroph
Give an example
Use light and organic carbon
Purple / green bacteria
What is a chemoheterotroph
Give an example
Uses chemical energy and organic carbon source
Enterobacteria
What is a chemoautotroph
Give an example
Use chemnical energy and carbon dioxide as carbon source
Ammonia oxidising bacteria
What are the two additional terms used to seperate chemotrophs based on whether their carbon source is organic or inorganic
Organotroph = organic molecules
Lithotroph = inorganic molecules
Give an example of an energy source a chemolithotroph might use
H2
Fe2+
H2S
NH4+
What is another word for direct interaction between microbes
Antagonistic
ow can microbes interact indirectly
One species affects the environment to exclude another species
What is niche partitioning
Where microbes occupy the same space but compete for different resources
Explain how redox reactions can occue without movement of elevtrons
Redox reactions refer to a change in oxidation state
Oxidation increases the oxidation state, reduction decreases it
What does the oxidation state represent
The number of electrons that an atom can gain, lose or share when chemically bonding with an atom of another element
A reduced compound becomes … during oxidation
Oxidised
What is the role of oxidoreductases
Accept and transfer electrons in the electron transport chain
What are the first and second laws of energy (thermodynamic laws)
In energy transformations, the total energy remains constant
In energy transformations, some energy created disorder (entropy) and not work (systems tend to become more disordered)
What is enthalpy
The total energy of a system
What is enthalpy measured in
Joules (or heat)
What is the equation for enthalpy (H)
H = G + T * S
G - free energy
T - temperature
S - entropy (disorder) = unusable energy
What is the equation for Gibbs free energy
∆G = ∆H - T∆S
∆H - heat energy released or absorbed (enthalpy)
∆S - measure of disorder (change in entropy)
T - temperature
If an organism absorbs heat from its environment, is ∆H positive or negative
Positive
If a reaction splits one molecule into two, does ∆S increase or decrease
Increases (more disorder)
Is ∆S more lilely to be positive for catabolic or anabolic reactions
Catabolic
What is Gibbs free energy used to predict
The direction of a chemical reaction
If ∆G is positive, which direction is the reaction likely to go in
Reverse
What are 3 other factors affecting biochemical reactions
Concentration of reagents
Environmental conditions
Linked reactions
Activation energy
Enzymes
What does ∆G˚ mean in terms of the environment
Standard conditions of temperature, pressure and reactant concentrations
What does ∆G˚’ mean in terms of the environment of a reaction
Standard conditions plus biochemically relebany conditions pH7 and water activity 1
What happens in hydrolysis
Chemical bonds broken via oxidation by water
Give an example of energy reactions being coupled with unfavourable reactions in a cell
Glucose phosphorylation coupled with ATP dephosphorylation
What is activation energy
Energy input required for a chemical reaction to occur
What effect to enzymes have on activation energy
Lower it
