MICR221 Lecture 7 - The Balance Of Anabolic and Catabolic Reactions Flashcards
what 2 sources do bacteria require to grow?
an energy source and a carbon source provided from either a different or the same molecule
what does the energy source for bacterial growth come from?
comes from catabolic reactions
what are catabolic reactions?
the breaking down of molecules into building blocks (monomers)
-break down of high energy molecules to release energy or directly power other reactions
what are anabolic reactions?
building up of molecules into cellular structures (polymers)
-assembly of cell macromolecules driven by cellular energy supplies
where does the carbon source for bacterial growth come from?
comes from 12 precursor metabolites that are made from several catabolic pathways
how do photoautotrophs make their own energy?
make their own energy using light and CO2 via photosynthesis
how do chemoheterotrophs derive their energy?
derives its energy from chemicals and needs to consume other organisms for survival
what requires the largest energy investment of a cells total energy in terms of synthesis?
to make new cells new polymers and new monomers need to be created and this is a huge energy investment
what percentage of the cells total energy is required to synthesise new polymers and monomers?
95% of the total energy
what percentage of the cells total energy to synthesise new polymers and monomers is required to synthesise proteins?
over 50% of the 95% of the total energy needed to synthesise new polymers and monomers
what percentage of the cells total energy to synthesise new polymers and monomers is required to synthesise lipids?
approx. 20% of the 95% of the total energy needed to synthesise new polymers and monomers
what percentage of the cells total energy to synthesise new polymers and monomers is required to synthesise RNA?
approx. 13% of the 95% of the total energy needed to synthesise new polymers and monomers
what percentage of the cells total energy to synthesise new polymers and monomers is required to synthesise DNA?
approx. 2% of the 95% of the total energy needed to synthesise new polymers and monomers
what percentage of the cells total energy is required to assemble into polymers?
5% of the total energy
what percentage of the cells total energy to assemble into polymers is required for proteins?
over 90% of the 5% of the total energy needed to assemble into polymers
what 2 sources are required for monomer synthesis?
the nutrients of nitrogen and sulfur
what must exisiting macromolecules make for replacement and repair during persistence?
proteins that repair DNA
proteins that stabilise RNA
a proton or sodium motive force (PMF)
what is a proton motive force (PMF)?
an electrochemical gradient where energy is stored in a buildup of H+ and other ions in the periplasm. This drives many transporters to uptake carbon/energy sources. PMF is required for high efficiency ATP synthesis.
what is the relationship between bacteria using Na+ ions and protons in a PMF?
some bacteria in a PMF use Na+ ions instead of protons
what systems do bacteria undertake for long-term survivial?
new cells continue to be made and metabolism is regulated to replace/repair all macromolecules. All persisters are metabolically active and primed for regrowth. Bacteria in energy-limited environments slow total growth and the relative ratio of energy production vs consumption is unchanged
what determines the balance between catabolism and anabolism?
determined by environmental conditions
e.g the energy in vs energy out
what is ATP?
an energy rich molecule that creates from phosphate hydrolysis to power other reactions through covalent reactions/intermediates
what is ATP produced by?
oxidative phosphorylation
what is NADH?
an electron rich molecule that powers oxidative phosphorylation and many central metabolic reactions
when is NADH produced?
produced during central carbon metabolism
what is NADPH?
the phosphorylated form of NADH that powers reduction reactions that form polymers
what is NADPH enzymatically produced from?
enzymatically produced from NAD+ or NADH
what is the relationship between NADH and NADPH?
both NADH and NADPH are reversible redox cofactors that allow for easy backwards rerouting of certain reactions compared to ATP
what is the function of phosphorylation?
used to create 2 seperate redox pools that are maintained at different ratios by the enzymes NAD kinase which phosphorylates and NADP phosphatase that reverses
what are the 2 enzymes that maintain the different ratios of the 2 seperate redox pools from phosphorylation?
NAD kinase
NADP phosphatase
what is the function of NAD kinase?
to phosphorylate
what is the function of NADP phosphatase?
to reverse
what does it mean if there is a higher ratio of NAD+ (NAD+/NADPH)?
catabolism is promoted
what does it mean if there is a lower ratio of NADPH (NADPH/NAD+)?
anabolism is promoted
what is redox balance?
the balance of the anabolism/catabolism ratios
what molecule is a reducing power equivalent?
NAD (P) H
what are transporters?
integral transmembrane proteins that can either be importers, exporters or reversable
what are importer transporters?
transporters involved in nutrient uptake
what are exporter transporters?
transporters involved in drug efflux
what are the 2 forms of transport?
active transport
passive transport
what is active transport?
when an energy source is used to rapidly accumulate molecules against a concentration gradient
what is primary active transport?
when ATP or an equivalent is hydrolysed for energy
what is secondary active transport?
when co-transport of another molecule provides the energy source
what is passive transport?
when molecules diffuse according to their concentration gradient
what are the 3 classes of bacterial transporters?
ATP binding cassette (ABC) superfamily
major facilitator superfamily (MFS)
group translocation –> e.g phosphotransferase system (PTS)
what are the advantages of active transport?
high affinity makes it more competitive for the scarce low concentration resources, allows for the rapid response to environmental fluctuations and allows cells to accumulate against a concentration gradient keeping the intracellular enzymes saturated with substrate
what are the disadvantage of active transport?
has a large energy cost and requires more complex proteins
what is the ATP binding cassette (ABC) superfamily transporter composed of?
it is a multi-subunit with 7 different subtypes existing with varying transport mechanisms
what is the function of the ATP binding cassette (ABC) superfamily transporter?
performs primary active transport using ATP as the energy source that can function as both an importer or exporter
what is the function of the major facilitation superfamily (MFS)?
performs facilitated diffusion of ions/solutes that do not otherwise cross the cell membrane either through passive or secondary active (co-transport) transport that is powered by concentration gradients
what is a uniport?
a membrane transport protein that transports a single species of substrate across a cell membrane
what is a uniport in terms of the major facilitation superfamily (MFS)?
the uniport is passive for MFS and is driven by the concentration gradient of the main solute
what is an antiport?
a co-transporter and intergral membrane protein involved in secondary active transport
what is an antiport in terms of powering bacterial growth?
an antiport is active, and the concentration gradient of another molecule moving in the opposite direction is used
what is a symport?
an intergral membrane protein that is involved in the transport of 2 different molecules across the cell membrane in the same direction
what is a symport in terms of powering bacterial growth?
a symport is active and the concentration gradient of another molecule moving in the same direction is used
what is another name for group translocation?
phosphotransferase system
what is group translocation?
the cascade of phosphate transfer used to trap substrates in a cell from energy provided from phosphate to power transport
what is the relationship between the substrate used in group translocation and transport?
the substrate is modified during transport creating its own class of active transport (not primary or secondary transport)
