Enzymes

• What are enzymes, and how do they function in biological systems?

  Enzymes are biological molecules, typically proteins, that act as catalysts to speed up chemical reactions in living organisms. They function by lowering the activation energy required for a chemical reaction, allowing it to occur more rapidly.
• Explain the term "catalyst" as it relates to enzymes. Provide an example of a biological reaction catalyzed by an enzyme.

  A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process. An example of a biological reaction catalyzed by an enzyme is the digestion of starch into glucose by the enzyme amylase in the human digestive system.
• Enzymes are highly specific in their action. Describe the concept of enzyme-substrate specificity and provide an example?

  Enzyme-substrate specificity refers to the fact that each enzyme can catalyze a specific reaction with a specific substrate or set of substrates. For example, the enzyme lactase is specific to lactose, breaking it down into glucose and galactose.
• What is the lock-and-key model and the induced-fit model? How do they relate to enzyme-substrate interactions?

  The lock-and-key model suggests that enzymes and substrates have complementary shapes that fit together like a lock and key. The induced-fit model suggests that the enzyme's active site can change its shape to accommodate the substrate. Both models explain the specificity of enzyme-substrate interactions.
• List and briefly explain the four main factors that can affect enzyme activity?

  - Temperature (affecting reaction rate)

  • pH (affecting enzyme shape and function)
  • Substrate concentration (affecting reaction rate)
  • Presence of inhibitors or activators
• Discuss the effects of temperature on enzyme activity, and explain why extreme temperatures can denature enzymes.

  Enzymes have an optimal temperature at which they work best. As temperature increases, enzyme activity generally increases due to higher kinetic energy. However, extreme temperatures (too high or too low) can denature enzymes by disrupting their protein structure, rendering them non-functional.
• What is the optimal pH for most enzymes, and how does pH affect enzyme activity?

  The optimal pH for most enzymes is around 7 (neutral). pH affects enzyme activity by influencing the charge and shape of the enzyme. Significant deviations from the optimal pH can denature enzymes and reduce their activity.
• Enzyme inhibition plays a crucial role in regulating metabolic pathways. Describe the difference between competitive and non-competitive inhibition.

  Competitive inhibition occurs when a molecule (the inhibitor) competes with the substrate for the enzyme's active site. Non-competitive inhibition occurs when an inhibitor binds to a site on the enzyme other than the active site (the allosteric site), altering the enzyme's shape or function.
• Describe the role of coenzymes and cofactors in enzyme function.

  Coenzymes and cofactors are molecules that assist enzymes in their catalytic activity. Coenzymes are organic molecules that help enzymes in their reactions. Cofactors are inorganic ions or non-protein molecules that stabilize the enzyme's structure or participate in catalysis.
• Provide examples of enzymes involved in digestion and explain their functions in breaking down food.

  • Amylase: Breaks down starch into sugars.
  • Proteases: Break down proteins into amino acids.
  • Lipases: Break down fats into fatty acids and glycerol.
  • Nucleases: Break down nucleic acids (DNA and RNA).
• What is the significance of feedback inhibition in metabolic pathways, and how does it relate to enzyme regulation?

  Feedback inhibition is a mechanism where the end product of a metabolic pathway inhibits an earlier enzyme in the pathway, preventing overproduction. It helps regulate metabolic processes efficiently and prevent wasteful resource utilization.
• Explain the terms "allosteric site" and "cooperativity" in the context of enzyme regulation.

  An allosteric site is a site on an enzyme other than the active site where molecules (allosteric effectors) can bind to modulate the enzyme's activity. Cooperativity occurs when one substrate molecule binding to an enzyme's active site enhances the binding of additional substrate molecules to other active sites on the same enzyme.
• Discuss the enzyme-related diseases or conditions such as phenylketonuria (PKU).

  • a genetic disorder that affects the body's ability to process phenylalanine.
  • individuals with PKU lack an enzyme called phenylalanine hydroxylase which makes phenylalanine into tyrosine.
  • can result in intellectual disabilities, seizures, and other neurological issues.
  • change in diet can help
• What is irreversible enzyme inhibition.

  Irreversible enzyme inhibition involves the formation of strong, covalent bonds between the inhibitor and the enzyme, rendering the enzyme permanently inactive.
• Allosteric regulation occurs when a molecule binds to an allosteric site on an enzyme, causing a conformational change that either increases or decreases the enzyme's activity.
• what is an enzyme-substrate complex?

  Temporary complex formed when an enzyme binds to its substrate during a chemical reaction.