AP Bio Chapter 8: Metabolism Flashcards

Metabolism Reactions

• Catabolic reactions release energy by breaking down larger molecules.
• Anabolic reactions consume energy to build up larger molecules.
• Photosynthesis is an anabolic reaction; it requires energy to synthesize glucose.
• Cellular respiration is a catabolic reaction that releases energy.

Energy Concepts

• Kinetic energy is the energy of motion; potential energy is stored due to an object's position or structure.
• Water behind a dam and a mole of glucose both possess potential energy.

Free Energy

• Free energy (symbol: G) indicates the portion of energy in a system that can perform work under uniform conditions.
• Change in free energy is represented by the equation: ∆G = ∆H - T∆S.
• In exergonic reactions, ∆G is negative; for cellular respiration, it is -686 kcal/mol.

Cellular Work Types

• Cells perform three main types of work:
  • Chemical work: synthesizing polymers from monomers.
  • Transport work: moving substances across membranes against their gradient.
  • Mechanical work: activities like cilia beating and muscle contraction.

ATP and Energy Release

• The hydrolysis of ATP (ATP → ADP + Pi) releases -7.3 kcal/mol of energy, categorized as an exergonic reaction.
• Energy coupling refers to using the energy from exergonic processes to drive endergonic reactions.

Enzymatic Action

• Catalysts speed up reactions without being consumed.
• Activation energy (Ea) is the energy required to initiate a chemical reaction.
• Induced fit describes how enzymes adjust their shape to better catalyze reactions.
• Enzyme specificity is influenced by protein structure.

Factors Affecting Enzymes

• The rate of enzyme action can be affected by substrate concentration; more substrate can lead to increased reaction rates until saturation.
• Extreme pH levels and temperatures can denature enzymes, rendering them inactive.
• Pepsin, a digestive enzyme, functions at a pH of 2, found in the stomach.

Cofactors and Inhibitors

• Cofactors are inorganic, while coenzymes are organic; examples include zinc for cofactors and vitamins for coenzymes.
• Competitive inhibitors block substrates from binding to the active site, while noncompetitive inhibitors bind at a different site, altering enzyme shape and function.

Allosteric Regulation

• Allosteric regulation modifies enzyme activity, with regulatory molecules binding at sites other than the active site.
• Allosteric activators enhance enzyme activity, whereas allosteric inhibitors decrease it.
• Hemoglobin demonstrates cooperativity in O₂ binding, enhancing its efficiency in oxygen transport, particularly in the gills of fish.