Topic 5: Metabolism

• What are the forms of energy mentioned in the study material?

  Kinetic and potential energy
• Where does the energy that sustains most of Earth's life forms come from?

  It comes from the sun
• What is the definition of metabolism?

  The sum of the chemical reactions that take place within each cell of a living organism
• What are anabolic reactions?

  Reactions that build up complex molecules from simple ones

  
• What are catabolic reactions?

  Reactions that break down complex molecules into smaller ones

  
• What is bioenergetics?

  The study of energy flow through a living system
• What are the two main types of organisms based on their carbon source?

  Autotrophs and heterotrophs
• What is the difference between phototrophs and chemotrophs?

  Phototrophs obtain energy from sunlight, while chemotrophs obtain energy from chemical compounds
• What is the role of ATP in metabolism?

  ATP provides energy for various cellular processes
• How is energy from the sun used in photosynthesis?

  It is captured to convert CO2 and H2O into glucose
• What happens to the energy stored in glucose during cellular respiration?

  It is released, regenerating CO2 and H2O
• What is Gibb's Free Energy (G)?

  The amount of energy available to do work
• What does a negative ΔG indicate about a reaction?

  Energy is released and the reaction is spontaneous

  
• What is activation energy?

  The energy required for a reaction to proceed

  
• How does the first law of thermodynamics relate to energy transformation?

  It states that energy cannot be created or destroyed, only transformed
• What does the second law of thermodynamics state?

  Energy transfer is not completely efficient and increases entropy
• What is the role of decomposers in energy flow?

  They break down dead organisms and recycle energy

  
• Why are there typically no more than five trophic levels in a food chain?

  Energy loss at each level limits the number of levels
• What is the structure of ATP?

  ATP consists of adenine, ribose, and three phosphate groups

  
• What happens when a phosphate group is removed from ATP?

  Energy is released

  
• What is gluconeogenesis?

  The process of making glucose from non-carbohydrate sources
• What is the role of enzymes in metabolic reactions?

  Enzymes speed up reactions by lowering activation energy
• What is enzyme-substrate specificity?

  Enzymes are very specific and catalyze a single reaction
• How do competitive inhibitors affect enzyme activity?

  They compete with the substrate for the active site

  
• What is end product inhibition?

  It occurs when the end product binds to an enzyme in the pathway

  
• What is the function of lactase?

  It breaks down lactose into glucose and galactose
• What factors affect enzyme activity?

  Temperature, pH, enzyme concentration, and substrate concentration
• How does temperature affect enzyme activity?

  Enzymes work at optimal temperatures, and extreme temperatures can denature them

  
• What is the optimal pH for pepsin and trypsin?

  Pepsin works at a low pH, while trypsin works at a high pH

  
• What is the relationship between enzyme concentration and reaction rate?

  The rate of reaction increases with enzyme concentration until a certain point

  
• What are the functions of ATP in cellular processes?

  • Provides energy for metabolic reactions
  • Involved in gluconeogenesis
  • Active transport (e.g., sodium-potassium pump)
  • Cellular signaling
  • Nucleic acid synthesis
  • Protein synthesis
  • Muscle contraction
  • Phagocytosis
  • Acts as a neurotransmitter

  
• What are the strengths and weaknesses of enzyme regulation?

  Strengths:

  • Allows cells to control metabolic processes
  • Adjusts enzyme activity based on cellular needs

  
  

  Weaknesses:

  • Can lead to metabolic disorders if regulation fails
  • Inhibitors can disrupt normal enzyme function
• What are the types of enzyme inhibitors?

  • Competitive inhibitors: Compete with substrate for active site
  • Noncompetitive inhibitors: Slow reaction rate without competing for active site

  
• What is the significance of enzyme cofactors and coenzymes?

  • Cofactors: Inorganic ions (e.g., Fe++, Mg++, Zn++) required for enzyme function
  • Coenzymes: Organic molecules (e.g., ATP, NADH+, vitamins) that assist enzymes
• What is the role of enzymes in metabolic pathways?

  • Enzymes catalyze biochemical reactions
  • Each product of one reaction serves as the substrate for the next
  • They increase the rate of metabolic reactions
• How do enzymes lower activation energy?

  • By binding to reactants and stabilizing the transition state
  • They promote bond-breaking and bond-forming processes
• What is the importance of enzyme specificity?

  • Enzymes are specific to one substrate
  • This specificity ensures that metabolic pathways function efficiently
• How does enzyme activity change with temperature and pH?

  • Enzymes have optimal temperature and pH ranges
  • Extreme conditions can denature enzymes and reduce activity

  
• What is the significance of metabolic pathways?

  • They convert substrates into final products through a series of reactions
  • They are essential for energy production and synthesis of biomolecules

  
• What is the relationship between energy flow and trophic levels?

  • Energy decreases at each trophic level due to loss as heat
  • Fewer organisms can be supported at higher trophic levels