Microbial Metabolism Quiz

Microbial Metabolism

• Metabolism is the sum of all chemical reactions in a living organism. It includes both the building up (anabolism) and breaking down (catabolism) of nutrients.
• ATP (adenosine triphosphate) is a crucial molecule in metabolism as it stores and transfers energy. Anabolic reactions use energy from ATP, while catabolic reactions generate ATP.
• Enzymes are proteins that catalyze biochemical reactions. They lower the activation energy needed for the reactions to occur and are specific for the substrates they work on.
• Cofactors (inorganic ions or coenzymes) help enzymes function. Their presence or absence influences enzymatic activity.
• Ribozymes are RNA molecules that act as enzymes, catalyzing reactions on RNA.
• Oxidation and reduction reactions are coupled. Oxidation is the loss of electrons and reduction is the gain of electrons. These reactions are key to extracting energy from nutrients.
• Organisms use three main mechanisms for phosphorylation to generate ATP from ADP: substrate-level phosphorylation, oxidative phosphorylation, and photophosphorylation.

Metabolic Pathways & Application

• Metabolic pathways are coordinated sets of reactions achieving common goals.
• Catabolic pathways break down complex molecules, releasing energy in the process.
• Anabolic pathways build complex molecules, using energy from catabolic pathways.
• Microbial metabolism is critical in various applications, including:
  • Nitrogen cycle: Conversion of atmospheric nitrogen into forms usable by other organisms.
  • Sewage treatment: Removal of organic matter from wastewater.
  • Food and beverage production: Fermentation of sugars to create products like beer and wine.
  • Drug production: Synthesis of antibiotics and other medications.

Enzymes & Chemical Reactions

• Enzymes are proteins that catalyze biological reactions by lowering the activation energy.
• Substrates bind to the active sites on enzymes.
• Enzymes are not consumed or changed during the reactions they catalyze; their shape is key to function.
• Enzyme activity is influenced by factors such as temperature, pH, and substrate concentration.
• Enzumes are highly specific to their substrates, and the active site accommodates only the appropriate substrate.
• Denaturation occurs when enzymes lose their 3-D structure, and are no longer functional (temperature, pH, chemicals).

Factors influencing Enzyme Activity

• Temperature: Enzymes have an optimal temperature range for activity; exceeding this range can denature them
• pH: Enzymes also have an optimal pH range; deviations from this range can lead to denaturation
• Substrate concentration: Increasing substrate concentration leads to higher reaction rates until all enzymatic active sites are occupied.
• Enzyme concentration: Increasing enzyme concentration also usually increases the rate

Inhibitors

• Inhibitors are molecules that decrease enzyme activity.
• Competitive inhibitors block the active site, competing with the normal substrate for the same location; its shape is almost identical to the normal substrate.
• Non-competitive inhibitors bind to the allosteric site (an enzyme's site other than the active site) causing a change in the enzymes shape, making it non-functional.

Ribozymes

• Ribozymes are RNA molecules that act as enzymes. They catalyze reactions on RNA molecules.
• Ribozymes have active site for specific substrate, similar to protein catalysts.
• They are crucial in protein synthesis and are not consumed in the chemical reaction.

Energy Production

• Nutrient molecules contain energy stored in their electron bonds and can then form higher energy bonds.
• Catabolic pathways concentrate the energy into ATP.
• ATP is a high-energy molecule acting as a usable energy currency, needed for cellular work.

Oxidation-Reduction Reactions

• Oxidation-reduction (redox) reactions are coupled processes. One substance is oxidized (loses electrons) while another is reduced (gains electrons).
• Redox reactions in catabolism extract energy from nutrients.

ATP Generation

• Phosphorylation is the process of adding a phosphate group to a molecule.
• Organisms use three mechanisms for ATP generation:
  • Substrate-level phosphorylation.
  • Oxidative phosphorylation.
  • Photophosphorylation.

Overview of Respiration and Fermentation

• Metabolic pathways, like respiration, yield substantial amounts of ATP.
• Most organisms use respiration or fermentation.
• Respiration is an oxygen requiring process (aerobic).
• Fermentation does not require oxygen (anaerobic).
• Both processes start with glycolysis but diverge significantly after.

Glycolysis

• Glycolysis is the initial stage of carbohydrate catabolism.
• It breaks down glucose into pyruvic acid.
• It occurs in most organisms.
• It does not require oxygen.

Additional Pathways to Glycolysis

• Other ways organisms break down glucose exist which combine with glycolysis (Pentose Phosphate and Entner-Doudoroff). They support diverse biochemical needs beyond glucose breakdown.

Carbohydrate Catabolism & Metabolism in various organisms

• Organisms break down carbs for cellular energy, using respiration and fermentation.
• Glucose is a common energy source in carbohydrate catabolism
• Various pathways of catabolism function in concert with one another to support cellular function and diverse metabolic needs.
• Different organisms use diverse methods of breaking down glucose based on whether or not oxygen is present.

Biochemical Tests & Bacterial Identification

• Biochemical tests differentiate bacteria based on their metabolic abilities.
• Different organisms have different requirements for various substances and create unique results with a number of lab tests.
• These metabolic indicators are important for diagnosing and identifying bacteria.

Cellular Respiration

• Respiration is a critically important metabolic pathway for ATP generation & is the ultimate source of energy for many cellular processes.
• Two types of respiration (aerobic + anaerobic) each using differing end electron acceptors.
• The Krebs cycle is an essential part of aerobic respiration, releasing potential energy from acetyl compounds to produce substantial ATP.
• The electron transport chain is the major way the body generates ATP: pumping hydrogen ions (H⁺), creating an electrochemical gradient, to power ATP synthase & produce ATP.

Lipid Catabolism

• Glycerol is catabolized, through multiple steps, into a molecule used in the Krebs cycle.
• Fatty acids are degraded through a process called beta-oxidation, producing acetyl-CoA, also used in the Krebs cycle.
• Amino acids require deamination (removing the amino group) to be processed into other metabolic pathways which also use the Krebs cycle.

Test your knowledge on microbial metabolism, including anabolism, catabolism, and the role of ATP in energy transfer. This quiz covers enzymatic functions, cofactors, and the importance of oxidation-reduction reactions. Understand the intricate processes that govern living organisms' biochemical reactions.