Soil 5 - Metabolism & Energetics Flashcards
What are the 4 stages of bacterial growth?
- Lag time
- Growth Phase (exponential)
- Stationary Phase
- Death phase (logarithmic decline)
How could you calculate generation time?
g = t/n
t: time of growth
n: number of generations
The growth rate is measured in which units?
number of generations per hour
What are the 5 resources needed by all life?
- Energy
- electrons
- Major (macro) nutrients
- Trace (micro) nutrients
- Growth factor
What controls metabolism?
- an emergent property of the many inputs/outputs of materials/energy in a system
- most reactions are regulated by enzymes
How do you categorize different metabolisms? (3 traits)
- source of energy
- source of reducing equivalents (e-)
- source of carbon (for anabolism - building macromolecules)
What is the major pathway for breaking down glucose?
Glycolysis
What are the 4 major pathways of glycolysis?
- Respiration
- Fermentation
- Aerobic respiration
- Anaerobic respiration
What is fermentation?
when facultative and aerotolerant anaerobes use only the glycolysis scheme to incompletely oxidize glucose
What is aerobic respiration?
when oxygen is used as the final electron acceptor at the end of the respiration scheme
- produces H2O
What is anaerobic respiration?
Uses Nitrogen/N compounds/other inorganic substances as the final electron acceptor in respiration
Where do autotrophs get Carbon?
CO2
Where do heterotrophs get Carbon?
Organic compounds
When is ATP formed?
during respiration or fermentation
What are 3 possible electron acceptors?
- O2
- NO3
- SO4
How do metabolic reactions occur?
- in a multi-step pathway
- each step is catalyzed by an enzyme
How do enzymes work?
serve as a physical site for substrates (reacting molecules) to be positioned during a reaction
What is the energy of activation in a reaction?
the amount of energy needed for a reaction to proceed
What 3 ways are there to achieve energy of activation for a reaction?
- Increase thermal energy (+ molecular velocity)
- increase concentration of reactants (+ molecular collisions)
- Add a catalyst
What are coenzymes?
organic compounds that work in conjunctino with an apoenzyme to perform a necessary alteration of a substrate
What are 6 factors that affect how enzymes function?
- temperature
- pH
- acids/bases
- UV light
- concentration of substrates
- inhibitors
What is the most common kind of enzyme regulation?
feedback inhibition, where enzymatic reaction products are allosteric inhibitors
What are the two kinds of enzymes based on their position relative to the cell?
- Exoenzymes (active outside the cell)
- Endoenzymes (inside the cell)
What is the role of microbial enzymes in disease?
many pathogens secrete unique exoenzymes that avoid host defense/promote multiplication
(called virulence factors or toxins)
What are enzymes sensitive to, and how?
- their environment
- only operate under certain temp, pH, osmotic pressure
What happens when an enzyme is outside the conditions it needs?
they become labile (chemically unstable) or denature
What is the main difference in anaerobic respiration (compared to aerobic respiration)?
uses oxygen-containing molecules instead of oxygen as final e- acceptor
What are the 4 end products of fermentation?
- acid (lactic acid, acetic acid etc)
- alcohol
- gas (CO2, H2)
- contaminants
What are two types of acid fermentation?
- many varied pathways, but split into 2 groups(?)
1. Heterolactic fermentation (mix of lactic, acetic, CO2)
2. Mixed acid fermentation (acetic, lactic, succinic, formic acid)
What are the 3 major modes of ATP production?
- obligate anaerobes
- obligate aerobes
- facultative anaerobes
What are the two sources of macromolecules? (ex sugars, amino acids, etc)
- enter from outside the cell as nutrients
- form within the cell through cellular pathways
What are the 2 energy sources for autotrophic processes?
- Light (photoautotrophs)
- Chemical (chemoautotrophs)
Where do lithotrophs get reducing equivalents (e-)?
inorganic compounds
Where do organotrophs get reducing equivalents (e-)
organic compounds
What happens in a redox rxn?
- oxidation - electrons are removed
- reduction - electrons are gained
Is there only one type of chlorophyll?
No! Diversity in two groups:
- chlorophyll (oxygenic)
- bacteriochlorophyll (anoxygenic)
What are some traits of anoxygenic photosynthesizers?
- possess bacteriochlorophyll
- versatile in capturing light
- only have cyclic photosystem 1
- use H2, H2S, or S2 rather than H2O for electrons
- anoxygenic!
What are the 3 main aerobic layers in a Winogradsky column?
- aerobic
- microaerophilic
- anaerobic
What are the 4 main biotic layers in a Winogradsky column?
- Cyanobacteria/algae
- Nonsulfur photosynthetic bacteria
- purple photosynthetic bacteria
- green photosynthetic bacteria
