Cellular Metabolism and Enzymes Quiz

Cellular Metabolism and Enzymes

• Macromolecular diversity: Modifications allow for diverse functions from a limited set of proteins.
• Toxicity: Excessive amounts of any substance can be harmful to cells.
• Reaction types: Anabolic reactions build molecules, requiring energy; catabolic reactions break them down, releasing energy.
• Steroid function: Steroids contribute to muscle building.
• Thermodynamic laws: All chemical reactions adhere to the first and second laws of thermodynamics.
  • First law: Energy cannot be created or destroyed, only transferred or transformed. The total amount of energy in the universe is constant.
  • Second law: Every energy transfer results in some usable energy being lost as heat. Heat is a less utilizable form of energy for cellular work.
• Reactants and products: Reactants are the starting materials in a reaction; products are the resulting materials.
• Endergonic and exergonic reactions:
  • Endergonic reactions require energy input to proceed, and products contain more energy than reactants.
  • Exergonic reactions release energy as they proceed, and reactants contain more energy than products.
• Coupled reactions: Endergonic reactions are often coupled to exergonic reactions to provide the necessary energy.
• Activation energy: All reactions require activation energy, an initial energy input to get the reaction started. This is analogous to the energy required to move two objects together.
• Catalysts and enzymes: Catalysts, such as enzymes, speed up reactions by lowering activation energy. Enzymes are biological catalysts.
• Enzyme function:
  • Enzymes are recycled.
  • Enzymes lower activation energy.
  • Activation energy can be lowered by changes in heat or arrangement.
  • Enzymes typically end in the suffix "-ase."
• Ligands and receptors: Ligands bind to receptors, and affinity, or attraction, refers to the strength of this interaction.
• Enzyme kinetics:
  • Factors affecting reaction rate include substrate concentration and enzyme affinity. Enzymes are efficient at low substrate concentrations.
  • Enzyme activity is influenced by temperature and pH. Optimal conditions exist where enzyme activity is highest.
  • Extreme temperatures or pH conditions can cause enzyme denaturation.
  • Enzyme regulation: - Kinases add phosphate groups to enzymes, activating them. - Phosphatases remove phosphate groups, deactivating enzymes. - Many enzymes' roles are to activate other enzymes. - Metabolic pathways are chains of linked reactions. - Feedback inhibition can regulate metabolic pathways. For instance, if a product builds up, it can inhibit the production process.
  • ATP: Adenosine triphosphate (ATP) is the cell's primary energy currency, powering many endergonic reactions.
  • ATP hydrolysis: ATP hydrolysis (breaking down ATP with water) into ADP (adenosine diphosphate) and Pi (inorganic phosphate) is a highly exergonic reaction releasing energy.
• Cellular respiration:
  • Glycolysis is the first step in cellular respiration, occurring in the cytoplasm, and does not require oxygen.