enzymes Flashcards
(10 cards)
What is metabolism, and what are its functions? (5 marks)
A:
Definition: Totality of chemical reactions occurring within a cell or organism.
Controlled by: Enzymes coordinating interdependent processes.
Functions:
Provide energy for processes like movement and reproduction.
Enable synthesis and assimilation of organic materials.
Convert nutrients into energy, excrete waste.
Compare anabolic and catabolic reactions. Provide examples. (3 marks)
A:
Anabolism:
Builds complex macromolecules from simpler biomolecules.
Examples: Photosynthesis, formation of organic polymers.
Catabolism:
Breaks down macromolecules into simpler building blocks.
Examples: Digestion (via hydrolysis), respiration (via oxidation).
Mnemonic: “Anna Builder.”
Mnemonic: “Cat Breaker.”
What are enzymes, and how do they work? (2 marks)
A:
Definition: Globular proteins that increase the rate of chemical reactions.
Characteristics:
Not consumed during reactions.
Can be reused.
Mechanism: Substrates bind to enzyme active sites and are converted into products.
What is substrate specificity, and how is it determined? (2 marks)
A:
Active Site: Region on the enzyme where substrates bind.
Complementary Fit: Shape and charge match the substrate.
Unique Shape: Composed of specific amino acids; each enzyme is specific to its substrate.
How is enzyme activity measured? (3 marks)
A:
Metrics: Consumption of substrates or formation of products.
Methodologies:
Catalase: Hydrogen peroxide → Oxygen (measure pressure change).
Pectinase: Pectin → Simple sugars (measure weight loss).
Pepsin: Protein → Short polypeptides (observe color change).
Rennin: Casein (soluble) → Casein (insoluble) (measure precipitate).
How do enzymes affect activation energy? (2 marks)
A:
Role: Enzymes lower the activation energy threshold.
Effect:
Without enzymes: Higher activation energy limits reaction rates.
With enzymes: Reaction rates increase due to reduced energy threshold.
What is the induced-fit model, and how does it work? (2 marks)
A:
Definition: Active site changes shape to fit the substrate.
Effects:
Improves binding by conformational change.
Promotes catalytic activity by stressing substrate bonds.
Allows broad specificity (e.g., lipases binding various lipids).
What factors influence enzyme activity? (3 marks)
A:
Temperature:
Low: Insufficient energy for collisions.
Optimal: Peak reaction rate.
High: Denaturation disrupts active site shape.
pH:
Optimal: Maximum enzyme activity.
Deviations: Alter enzyme charge, solubility, and structure.
Substrate Concentration:
Increased substrate: More collisions, higher reaction rate.
Saturation point: Enzymes fully occupied; rate plateaus.
Enzyme Concentration: Directly proportional to reaction rate until saturation.
Why are molecular collisions important in enzyme activity? (2 marks)
A:
Requirement: Substrate must collide with the enzyme’s active site in the correct orientation.
Improvement Strategies:
Increase molecular motion (kinetic energy).
Increase substrate or enzyme concentration.
Immobilize enzymes or substrates to localize reactions.
What is enzyme denaturation, and what causes it? (4 marks)
A:
Definition: Loss of enzyme’s 3D structure, impairing activity.
Causes: High temperatures, extreme pH levels.
Impact:
Substrate can no longer bind to the deformed active site.
Reaction rate decreases significantly.
