Biology Metabolism and Enzymes Quiz

Metabolism

• A set of chemical reactions within living organisms that sustain life
• Enables growth, reproduction, maintenance, and environmental response
• Divided into two categories: catabolism and anabolism

Catabolism

• Breaks down large molecules into smaller units, releasing energy
• Example: glycolysis, the breakdown of glucose for energy

Anabolism

• Synthesizes complex molecules from smaller units, consuming energy
• Example: the construction of amino acids into proteins
• Example: glycogenesis, the conversion of glucose into glycogen

Enzymes

• Biological catalysts that speed up chemical reactions without being altered
• Made of proteins, their complex structure enables catalytic activity
• Many enzyme names end in "-ase" (e.g., maltase, lactase)

Activation Energy

• The minimum energy required for reactants to initiate a reaction
• Enzymes lower activation energy, allowing more reactants to participate

Lock-and-Key Model

• Enzyme's active site binds specifically to the substrate, enabling the reaction

Factors Affecting Enzyme Activity

• Temperature: most enzymes have an optimal temperature range, outside of which activity decreases due to denaturation
• pH: enzymes function best within a narrow pH range, extreme pH denatures enzymes
• Enzyme Activation: some enzymes are initially inactive and require activation within cells
• Substrate Concentration: increasing substrate concentration increases the rate of reaction until saturation point is reached

Homeostasis

• The body's ability to maintain a stable internal environment, despite external fluctuations
• Relies on feedback mechanisms: negative and positive feedback

Negative Feedback

• The most common type
• Counteracts changes in a physiological variable, restoring balance
• Example: regulating blood glucose levels, body temperature

Positive Feedback

• Amplifies the initial change, accelerating the process
• Example: blood clotting cascade, childbirth

Metabolism

• A set of chemical reactions occurring within the cells of a living organism to sustain life
• Catabolism breaks down large molecules into smaller units, releasing energy (e.g., glycolysis)
• Anabolism synthesizes complex molecules, consuming energy (e.g., creating proteins from amino acids, glycogenesis)

Enzymes

• Biological catalysts that speed up chemical reactions without changing the nature of the reaction
• Remain unchanged at the end of the reaction
• Primarily made of proteins
• Have names ending in "-ase" (e.g., maltase, lactase)

Activation Energy

• The energy required for reactants to begin a reaction
• Enzymes lower the activation energy, increasing reaction rate
• More reactants can participate in the reaction with the help of enzymes

Mechanism of Enzyme Action: Lock-and-Key Model

• Enzymes have a specific active site that binds to the substrate (the molecule the enzyme acts upon)
• This binding allows the enzyme to catalyze the reaction

Factors Affecting Enzyme Rate

• Temperature: Most enzymes are inactive at low temperatures but increase activity with higher temperatures up to a specific point
• pH: Each enzyme has an optimal pH for maximum activity
• Enzyme Activation: Some enzymes are produced in an inactive form (zymogens) and later activated (e.g., digestive enzymes in the pancreas)
• Substrate Concentration: Increased substrate concentration increases reaction rate until it reaches a maximum rate when the enzyme is saturated

Homeostasis

• The ability of an organism to maintain stable internal conditions despite external changes (e.g., blood glucose levels, body temperature)
• Often regulated by negative feedback mechanisms

Negative Feedback

• The most common feedback mechanism
• The body's response counteracts the change that initiated it
• Helps to restore balance to the system

Positive Feedback

• The body's response amplifies the initial change
• Can cause rapid changes in a physiological variable
• Often used for rapid processes, like childbirth

Metabolism

• A set of chemical reactions that happen in living cells to sustain life
• Allows an organism to grow, reproduce, maintain its structure, and respond to its environment
• Catabolism breaks down large molecules into smaller units & releases energy
  • Example: Glycolysis breaks down glucose for energy
• Anabolism synthesizes complex molecules and consumes energy
  • Examples:
    • Amino acids combine to form proteins
    • Glycogenesis: Glucose is converted into glycogen

Enzymes

• Biological catalysts that increase the rate of a chemical reaction without being changed themselves
• Are proteins with complex structures for their catalytic actions
• Mostly named with the suffix "-ase" (e.g. maltase, lactase)
• Activation energy is the amount of energy required for a reaction to occur
  • Enzymes lower the activation energy, making reactions proceed more easily
• Lock-and-Key model describes how enzymes bind to substrates
  • Enzymes have an active site where the substrate binds specifically, and the reaction is catalyzed

Factors Affecting Enzyme Activity

• Temperature affects enzyme activity
  • Activity increases with increasing temperatures until an optimum temperature is reached
  • Further increases in temperature lead to denaturation, where the enzyme loses its active conformation and becomes inactive
• pH affects enzyme activity
  • Each enzyme has a pH optimum where it functions best
  • Extreme pH values can lead to denaturation
  • The pH optimum of an enzyme usually reflects the pH of the body fluid where it is found
• Cofactors are usually metal ions (e.g. Ca2+, Mg2+, Cu2+, Zn2+) required for enzyme function
• Coenzymes are small organic molecules required for enzyme function
  • Usually derived from water-soluble vitamins
• Enzyme activation involves producing enzymes in an inactive form (zymogens) that are activated later within the cell
  • Example: Digestive enzymes in the pancreas are produced as zymogens and become active in the intestine
• Substrate concentration affects enzyme activity
  • As substrate concentration increases, the rate of the reaction increases until a maximum rate is reached
    • At this point, the enzyme is said to be saturated
• Reversible reactions can be influenced by enzyme concentration:
  • Increasing enzyme concentration also increases the rate of the reaction

Homeostasis

• The body's ability to maintain a stable internal environment despite external changes
  • Examples: Maintaining blood glucose levels and body temperature
• Feedback mechanisms regulate physiological events
  • Negative feedback is more common and involves a response that opposes the initial change
  • Positive feedback enhances the initial change and is less common

Important Words

• Metabolism: All chemical reactions in a living organism
• Catabolism: Breakdown of molecules
• Anabolism: Synthesis of molecules
• Enzyme: Biological catalyst
• Specific: Acting on a particular molecule
• Denatured: Loss of active conformation
• Saturated: All active sites on an enzyme are occupied
• Positive feedback: Amplifies initial change
• Negative feedback: Opposes initial change

Test your knowledge on metabolism, catabolism, and anabolism in living organisms. Explore the role of enzymes and their importance in biochemical reactions. This quiz covers key concepts such as activation energy and the lock-and-key model.