Microbial Metabolism (Part 1)

• 3 Types of cell work

  • Chemical
  • Transport
  • Mechanical
• Law of thermodynamics - Law of conservation of energy
• Entropy - the measure of randomness or disorder of the system
• The greater the disorder, the greater the entropy
• 2nd law of thermodynamics

  • When energy is used, the ending energy is lower.
• When energy is converted, it is from more useful to less useful
• Metabolism - The sum of all chemical reactions within a living organism
• Metabolism

  • Provides the energy necessary to maintain the structure of the cell repairing constituents, synthesizing new cellular components such as nucleic acids, polysaccharides (cell wall), and enzymes, energy for transporting substances, growth, reproduction, and movement.
• 2 classes of metabolism

  • Releases energy
  • Requires energy
• Respiration, fermentation, and photosynthesis

  • release energy to be utilized to synthesize macromolecules for the transport of nutrients and cellular movement
• Catabolism

  • The breakdown of complex organic compounds into simpler ones
  • Release energy in the form of ATP used by the cell for various functions
• Hydrolytic reactions

  • Reactions that use water and in which chemical bonds are broken
  • Exergonic
  • Produces more energy than they consume; gives off heat energy
• Exergonic - produces more energy than they consume; gives off heat energy
• Cellular respiration - break down of glucose molecule into CO2 and H2O
• Anabolism

  • The building of complex organic molecules from simpler ones
  • For growth, reproduction, and maintaining the cellular function (synthesis of the cell wall and nucleic acids, proteins, and lipids)
  • Requires energy input crucial for sustaining life
• Biosynthetic - The formation of chemical compounds by a living organism, or a laboratory process modeled after these reactions in living organisms
• Dehydration synthesis reactions

  • Reactions that release water
  • Endergonic
  • Consume more energy than they produce
• Endergonic - consumes more energy than they produce
• Key players for metabolism

  • Enzymes
  • ATP
• Enzymes

  • Cellular or biological catalysts that speed up chemical reactions without being permanently altered, proceed reactions rapidly
  • Ex. sucrase (hydrolysis of sucrose into glucose and fructose)
• ATP

  • Even if the enzyme is present, energy is still needed
  • Driver to manage energy
• Enzymes

  • Dictate metabolic pathways or sequences of chemical reactions that happen in the cells
  • By lowering the activation energy
  • Increases the rate at which substrates are being converted into products
• Collision theory - A fundamental concept in chemistry and physics that explains how reactions happen at the molecular level
• 2 Key factors of Collision theory

  • Collision frequency
  • Collision energy
• Collision frequency

  • Rate of collisions between reactant molecules, determines the likelihood of a reaction to happen; high concentration of reactants mas nagiging busy, increasing reaction rate
• Collision energy

  • Amount of energy required by the reacting molecule to be converted to product
• Activation energy - The minimum of kinetic energy
• Endoenzymes

  • Inside the cell; cytoplasm, mitochondria; involved in metabolic pathways and signaling cascades
• Exoenzymes

  • Synthesized inside and secreted outside the cell to catalyze reactions in the extracellular environment; periplasmic space; crucial role in digestion, nutrient acquisition defense mechanism, microbial interactions w the environment, degradation of organic matter where energy is acquired from their surroundings.
• Pepsin - A digestive enzyme
• Trypsin - Protease enzyme protein digestion
• Luciferase - Bioluminescence in fireflies
• Apoenzyme - protein factor
• Cofactor or Coenzyme - A non-protein component of enzyme
• Prosthetic group

  • If tightly, covalently attached to apoenzyme
  • Ex. heme/biotin
• Two of the most important coenzymes in cell metabolism

  • Nicotinamide Adenine Dinucleotide or NAD+
  • Nicotinamide Adenine Dinucleotide Phosphate or NADP
• NAD+

  • Catabolic or energy-yielding reactions
• NADP

  • Anabolic or energy-requiring reactions
• Coenzyme A

  • It contains derivatives of pantothenic acid or B vitamin; Krebs cycle synthesis and break down of fats, series of oxidizing reactions in Calvin cycle
• Holoenzyme

  • Fully functional enzyme
  • When cofactor or coenzyme binds to the apoenzyme, it forms holoenzyme
  • Capable of catalyzing reactions with high efficiency and specificity.