Ch.4 Energy Enzymes lecture notes/flashcards-Honey Ortiz

Chapter 4: Ground Rules of Metabolism

Key Concepts

• Energy

• Metabolism

• Enzymes

Energy in Ecosystems

• Most life forms derive energy from the sun.

• Photosynthesis: Plants convert sunlight into energy.

• Energy Transfer:

  • Herbivores consume plants for energy.

  • Carnivores eat herbivores.

  • Decomposers break down waste, recycling nutrients into the ecosystem.

Understanding Energy

• Definition: Energy is the capacity to do work.

• Types of Energy:

  • Kinetic Energy: Energy associated with motion.

  • Potential Energy: Stored energy found in chemical bonds.

Energy Transformations

• Thermodynamics: Study of energy transfer involving physical matter.

• 1st Law of Thermodynamics: Energy cannot be created or destroyed, only transformed or transferred.

• Energy has a one-way flow; often lost as heat.

• 2nd Law of Thermodynamics: Energy disperses spontaneously, spreading out over time.

Energy from the Sun

• The sun is the primary energy source for most life on Earth.

• Energy harvested undergoes multiple transfers before becoming permanently dispersed.

• Chemical Bonds: Resists energy's spontaneous dispersal, acting as potential energy stores.

Metabolism

• Definition: Refers to all chemical reactions in living organisms.

• Metabolic Pathways: Series of reactions that build, rearrange, or break down organic molecules, controlled by specific enzymes.

• Pathways are well-controlled and serve specific biological purposes.

Types of Metabolic Pathways

• Catabolic Pathways: Generate energy by breaking down larger molecules.
  - cat knocks down the tower of blocks

• Anabolic Pathways: Require energy to build up larger molecules.
  - Ana builds a tower with blocks

• Importance: Both pathways are essential for maintaining cellular energy balance.

Reactants and Products

• Reactant: Molecule that enters a reaction and undergoes change.

• Product: Molecule produced as a result of the reaction.

Enzymatic Action

• Catalysts: Agents that speed up chemical reactions without being used up/consumed.

• Enzymes: Proteins that act as catalysts in living cells.

• Role: Metabolism heavily relies on enzymes.

Activation Energy

• Definition: The initial energy input required to start a reaction.

• Methods to Overcome activation energy:

  • High heat (form of energy).

  • Utilizing enzymes to lower activation energy.

• Enzymes facilitate reactions by applying strain to bonds, aiding transition to product formation.

Properties of Enzymes

• Enzymes often end in “ase”

• Specificity: Each enzyme binds to specific substrates (reactants), undergoing particular changes (e.g., lactase (enzyme) only breaks down lactose (substrate).

• Models:

  • Lock and Key Model: Specificity of enzyme to substrate.

  • Induced Fit: Enzyme changes shape when substrate binds, allowing reaction to proceed.
    

• Enzymes remain free to catalyze further reactions once products leave the active site.

• Product: outcome of a reaction
  

Enzyme Terminology

• Substrate: The reactant that an enzyme acts on.

• Active Site: The region on the enzyme where substrates bind and reactions occur.

• Induced Fit: Minor changes in enzyme shape when substrate binds.

• Enzyme-Substrate Complex: Temporary molecule formed when an enzyme binds its substrate.

• Product Formation: New molecules formed as the outcome of the reaction.

Environmental Effects on Enzymes

• Environmental factors (pH, temperature, salt concentration) influence enzyme shape and job/function.

• Enzymes typically function optimally within a narrow range of conditions (temp and pH).

Enzymes and pH

• Example of two digestive enzymes:

  • Pepsin: Functions at pH 2 in the stomach.

  • Trypsin: Functions at pH 7.5 in the small intestine.

Enzyme Inhibition

• Competitive Inhibition: Inhibitor binds to the active site; competes with the substrate.

• Noncompetitive Inhibition: Inhibitor binds to allosteric site, altering active site functionality.

Summary

• Enzymes are crucial for metabolism, affected by their environment and capable of being inhibited through various mechanisms.