microbial metabolism Flashcards
key components, energy generation, anabolic metabolism, how microbes can be differentiated and environmental conditions affecting metabolism
metabolism definition
sum of all chemical reactions that occur inside a cell
catabolic definition
breakdown of complex molecules to release energy
anabolic definition
synthesis of complex molecules requiring energy
components of metabolism: substrates and products
- substrates: starting molecules or reactants in a metabolic reaction
- products: molecules generated by the reaction
components of metabolism: enzymes
biological catalysts that speed up metabolic reactions by lowering the activation.
Components of metabolism: energy carriers
ATP
- primary energy carrier in cells
- produced during catabolic reactions
Components of metabolism: energy carriers
electron carriers
- coenzymes that transfer electrons
- NAD+: oxidized form NAD+, reduced form NADH
- NADP+: oxidized form NADP+, reduced form NADPH
- also FAD/FADH… all these facilitate electron transfer
components of metabolism: electron donors and acceptors for redox reactions
- redox reactions: transfer of electrons from one molecule to another
- oxidation: molecule loses an electron
- reduction: molecule gains an electron
- involve loss of a H atom
components of metabolism:
regulatory molecules
- allosteric regulators: molecules binding enzymes at sites other than the active site to enhance or inhibit activity
- hormones: signals that regulate metabolic pathways based on the organism’s need.
components of metabolism: environmental conditions
- temperature and pH: affect enzyme activity and reaction rates
- availability of nutrients determining pathways activated
redox reactions
- transfer of electrons between two molecules
- Eg. lactate loses electrons to become pyruvate, coenzyme NAD+ is reduced to NADH
microbial metabolic pathways
- prokaryotes: respiration can be aerobic or anaerobic, fermentation is anaerobic
- eukaryotes: respiration is aerobic, fermentation is anaerobic.
catabolic pathways
- oxidative phosphorylation (mitochondria): relies on ETC and oxygen to produce ATP.
- substrate-level phosphorylation: generates ATP from a substrate without need for oxygen or ETC and occurs in glycolysis and citric acid cycle.
glycolysis (embden wtf???)
- anaerobic
- 2 ATP gain per glucose
- 2 NADH and 2 pyruvate
aerobic respiration
- complete oxidation of glucose using oxygen as final acceptor
- 38 ATP per glucose
aerobic respiration steps
- glycolysis: glucose to pyruvate
formation of 2 ATP, 2 NADH, 2 pyruvate - krebs/TCA
3 CO2, 1 ATP, 4 NADH, 1 FADH - electron transport chain
movement of electron across a chain or protein complexes and production of ATP
oxygen final electron acceptor
What is the final electron acceptor in anaerobic respiration?
An inorganic molecule other than oxygen (e.g., nitrate, sulfate).
What is chemiosmosis?
ATP synthesis using a proton gradient created by the Electron Transport Chain (ETC).
What enzyme is responsible for ATP synthesis in chemiosmosis?
ATP synthase.
What is gluconeogenesis?
Formation of glucose from non-carbohydrate precursors.
What are some precursors for gluconeogenesis?
Lactate, amino acids, glycerol, and TCA cycle intermediates.
What is the role of lipid biosynthesis in prokaryotes?
Producing fatty acids for membrane formation and energy storage.
What are the steps of protein synthesis?
Transcription: DNA → RNA
Translation: RNA → Protein
How are nucleic acids synthesized?
Nucleotides are synthesized from metabolic precursors.
How are microbes classified based on their energy source?
Phototrophs: Use light.
Chemotrophs: Use chemicals
How are microbes classified based on their electron source?
Lithotrophs: Use inorganic molecules.
Organotrophs: Use organic molecules
How are microbes classified based on their carbon source?
Autotrophs: Use CO₂.
Heterotrophs: Use organic carbon sources.
What are the oxygen requirements of microbes?
Obligate aerobes: Require oxygen.
Obligate anaerobes: Cannot survive in oxygen.
Facultative anaerobes: Can use oxygen but grow anaerobically if needed.
Microaerophiles: Require low oxygen levels.
Aerotolerant anaerobes: Tolerate oxygen but do not use it
What are the microbial temperature classifications?
Psychrophiles: Cold-loving (-5°C to 20°C).
Mesophiles: Moderate temperatures (20°C to 45°C).
Thermophiles: Heat-loving (45°C to 80°C)
How does pH affect microbial growth?
Acidophiles: Thrive in acidic environments.
Alkaliphiles: Thrive in basic environments.
What are some applications of microbial metabolism in industry and medicine?
Fermentation Technology: Producing antibiotics, alcohol, and organic acids (e.g., citric acid from Aspergillus niger).
Bioremediation: Using microbes to degrade pollutants (e.g., Pseudomonas for oil spills).
Pathogenesis: Pathogens rely on metabolic pathways to survive in hosts (e.g., Mycobacterium tuberculosis’ iron uptake).
