Topic 3-L1 - Overview of Microbial Metabolism Flashcards
Metabolic requirements for all life:
- Liquid water
- A source of energy to do work
- A source of electrons for biochemical reactions
- Nutrients (e.g. sources of carbon, nitrogen, etc)
Energy in microbes is constantly being used and some energy
lost as heat – need mechanisms to obtain energy from environment
Energy is conserved by storing it in high energy molecules –
ATP
Energy can be conserved in other energy-rich bonds as well - often
phosphate or sulfur bonds
Many ATPase enzymes in the cell – ATPases couple energy of
ATP hydrolysis to perform other reactions
Catabolism Reactions used to
obtain energy and break down complex molecules
Anabolism Reactions used to
synthesize cellular material (use energy)
Metabolism
Series of biochemical reactions needed to sustain life
Chemotrophs break down
high energy molecules to lower energy molecules – use excess energy to power cell functions
Phototrophs instead use the energy from
sunlight
Negative value : Gibbs free energy
= reactants more energy than products
= exergonic, releases energy
Positive value : Gibbs Free Energy
= reactants less energy than products
= endergonic, requires energy
ΔG is the measurement of
free energy change of a reaction (in kJ).
ΔGo’ can be calculated based on nature of
reactants/products.
Actual ΔG is effected by:
o Temperature
o Concentration of substrates
o Concentration of products
High K values (relatively high [products] ) increaseΔG values –
make reactions less energetically favourable in that direction
All cells need a usable source of the
basic elements (E.g. - C, N, P) that make up core molecules in the cell (E.g., DNA, protein, lipids)
Cells also need other elements that serve
essential cell functions, (E.g. Fe, Mg) – some elements are only required in trace amounts
Many microbes have evolved in environments where certain nutrients
are available and have
lost (or never had) the ability to make them
Autotrophs:
- Use CO2 (inorganic carbon) to build cell materials
- Takes a lot of energy
- Most chemolithotrophs and phototrophs
- Primary producers – very important – synthesize the organic molecules heterotrophs (like us) use
Heterotrophs:
- Obtain carbon from organic compounds.
- Nearly all chemoorganotrophs
