(LE2) Microbial Metabolism Flashcards
What are the two source categories all organisms need for proper metabolism function?
Carbon source and energy source
What are the two processes organisms acquire carbon?
Autotrophy: carbon comes from CO2 in the air
Heterotrophy: Carbon comes from consuming other organic matter
What are the processes organisms acquire energy?
Chemotrophy: From chemical processes
Phototrophy: light is energy source
What category of metabolism do plants fall into?
Photoautotrophs
What classification of metabolism are pathogens, most bacteria, fungi, protozoans, and all animals?
Chemoheterotrophs
What phase of metabolism is shown in the image? Explain this phase. Provide an example
Anabolism: building polymers from monomers
- energy is needed to build chemical bonds
- e.g. protein synthesis
What phase of metabolism is shown in the image? Explain this phase. Provide an example
Catabolism: breaking down polymers into monomers
- energy is released by breaking chemical bonds
- e.g. digestion
What is Collision Theory?
- substrates must make physical contact in order for a chemical reaction to occur
- All molecules have kinetic energy
What is activation energy?
- the amount of energy required to get a reaction started
What is reaction rate?
the frequency of collisions containing sufficient energy to bring about a reaction
How can we increase reaction rates?
- Increase kinetic energy by adding heat
- Lower activation energy requirements
What are enzymes?
Biological catalysts that speed up the rate of chemical reactions without being used
How do enzymes speed up the rate of chemical reactions?
- Decrease activation energy for reactants to reach high energy transition state
- Ensure reactants are in the proper orientation
What is turnover number?
number of substrates converted to products per second
ID and define what’s indicated in the image
Holoenzyme: the entire structure of the enzyme
ID and define what’s indicated in the image
Cofactor: (sometimes) inorganic component, often a metal ion (e.g. HgB and Fe)
ID and define what’s indicated in the image
Apoenzyme: protein component
ID and define what’s indicated in the image
Coenzyme: organic non-protein component, often derived from vitamins. Forms part of the active site
ID and define what’s indicated in the image
Catalytic site
What are the steps for the metabolism of enzyme action?
- Substrate(s) bind active site of enzyme
- Enzyme-substrate complex forms. Substrates are in proper orientation. “Transition state”
- Substrate is converted to product
- Products released
- Enzyme is unchanged during reaction. Ready to catalyze another reaction
What factors influence enzyme activity?
- Temperature
- pH
- Substrate concentration
- Enzyme inhibition
- Feedback inhibition
- Enzyme activation
Why does temperature affect enzyme activity?
High temp denatures (unfold) protein.
Enzymes work better at higher temp in their range. (b/c substrates move faster)
Why does pH affect enzyme activity?
Low and high pH denature protein
What is the effect on bacteria when the temperature is colder than their optimum temperature for growth? Hotter?
Colder - Bacteriostasis: enzymes are too slow for growth
Hotter - Bacteriocidal: kills enzyme and bacteria
How does substrate concentration affect enzyme activity?
Enzyme activity can slow if there are less substrates
Enzyme has max reaction rate when saturated substrate concentration is reached
What are the two types of enzyme inhibitors?
Competitive Inhibitors
Non-competitive Inhibitors
How do competitive inhibitors influence enzyme activity?
They are substrate analogs, so they compete for the active site
What happens if there are more competitive inhibitors than substrates?
Enzyme activity slows
Will increasing the substrate amount increase the reaction rate against competitive inhibitors? Increasing enzyme levels?
Increasing [S] will work. Increasing [E] will not because substrates will still be outcompeted by greater number of inhibitors
How do non-competitive inhibitors influence enzyme activity?
It binds to the allosteric site, not the active site which unfolds (changes shape) the active site
How can you increase the reaction rate against noncompetitive inhibitors?
Increase [E]
Not increase [S]
What is feedback inhibition? What is an example?
When the end-product of an enzymatic pathway inhibits one of the earlier reactions.
e.g., Threonine converting into Isoleucine, then Isoleucine binding to the allosteric site of the enzyme until enough isoleucine is created.
What are two types of enzyme activation? Provide examples
- Covalent modification (covalent bond; e.g. phosphorylation/dephosphorylation)
- Conformational change: enzyme needs to unfold to allow substrate to fit in active site. e.g. pepsinogen interacting with HCl to become Pepsin
What are the three types of ATP production?
- Substrate-level phosphorylation
- Photophosphorylation
- Oxidative phosphorylation
What method of ATP production is shown? What organisms perform this method?
Substrate-level phosphorylation: done in glycolysis
e.g. fermenters -> slow growth. 2 ATP/glucose molecule
What method of ATP production is shown? How does it work? What organisms perform this method? What is the energy yield?
Oxidative phosphorylation - electron energy captured in redox reaction to form phosphate bond.
e.g. aerobic/anaerobic respiration. Electron transport chain produces 34 ATP/glucose
What are redox reactions?
Transfer of e-
Reduction: gain e- (gain energy)
Oxidation: loss of e- (lose energy)
