4.1 - Enzyme Action Flashcards
Why are enzymes important in living organisms?
Enzymes are essential because they catalyze chemical reactions, allowing them to occur at a much faster rate without the need for extreme temperatures or pressures that would damage cells.
What would happen if enzymes were not present in living organisms?
Without enzymes, many of the chemical reactions necessary for life would not occur at the required speeds, making life processes impossible.
What are enzymes?
Enzymes are biological catalysts that are globular proteins. They interact with substrate molecules, speeding up reactions without needing harsh environmental conditions.
Why can’t living cells use extreme temperatures or pressures for chemical reactions?
Extreme temperatures and pressures would damage cell components, making them unsuitable for catalyzing reactions within living cells.
How do enzymes help chemical reactions occur in living organisms?
Enzymes lower the activation energy of reactions, allowing them to occur more quickly and efficiently under the mild conditions present in living cells.
What is the role of enzymes in anabolic reactions?
Enzymes catalyze anabolic reactions, which are building-up reactions, necessary for the synthesis and assembly of cell components like cellulose in plant cells and contractile proteins in muscles.
What are catabolic reactions and how are they related to enzymes?
Catabolic reactions are breaking-down reactions that release energy, such as the breakdown of glucose. These reactions are also catalyzed by enzymes.
How are large organic molecules obtained in living organisms?
Large organic molecules are obtained through the digestion of food, which is broken down by enzymes into smaller molecules like glucose.
What is metabolism and how do enzymes contribute to it?
Metabolism is the sum of all chemical reactions in a cell or organism. Enzymes control and organize these reactions, allowing them to proceed in an efficient and coordinated manner.
How do environmental conditions affect the rate of enzyme-catalyzed reactions?
Environmental conditions such as temperature, pressure, and pH can affect the rate of enzyme-catalyzed reactions, influencing the speed of cellular processes.
What is Vmax in the context of enzyme-catalyzed reactions?
Vmax is the maximum initial velocity or rate of an enzyme-catalyzed reaction, which is the highest rate at which the enzyme can operate, beyond which increasing the substrate concentration no longer increases the reaction rate.
Why do molecules need to collide in the right orientation for a reaction to occur?
For a reaction to happen, molecules must collide with the correct orientation so that the reactants can form products effectively. This increases the chances of a successful reaction.
How does increasing temperature and pressure affect the rate of reaction?
Increasing temperature and pressure speeds up the movement of molecules, leading to more frequent and successful collisions, which increases the overall rate of reaction.
What does the specificity of an enzyme refer to?
The specificity of an enzyme refers to the fact that each enzyme catalyzes only one specific type of chemical reaction, despite there being thousands of reactions in any given cell.
What is activation energy?
Activation energy is the minimum energy required for a chemical reaction to occur. It is the energy needed to start a reaction.
How do enzymes help reduce the activation energy of a reaction?
Enzymes help molecules collide successfully by lowering the activation energy needed, which makes reactions occur more easily under normal cellular conditions.
What are the two hypotheses for how enzymes reduce activation energy?
- The Lock and Key Hypothesis – the enzyme’s active site fits precisely with the substrate.
- The Induced Fit Hypothesis – the enzyme’s active site undergoes a conformational change when it binds to the substrate.
What is the active site of an enzyme?
The active site is a specific area within the tertiary structure of an enzyme that has a shape complementary to a particular substrate molecule, allowing the enzyme to catalyze a reaction.
What does the Lock and Key Hypothesis suggest about enzyme-substrate interaction?
The Lock and Key Hypothesis suggests that only a specific substrate will fit into the active site of an enzyme, just like a key fits into a lock. This forms an enzyme-substrate complex, leading to the formation of products.
What happens after the enzyme-substrate complex forms in the Lock and Key Hypothesis?
Once the enzyme-substrate complex forms, the substrate reacts, and the product or products are formed. These products are then released, leaving the enzyme unchanged and able to catalyze subsequent reactions.
How does the enzyme hold the substrate in the Lock and Key Hypothesis?
The enzyme holds the substrate in a way that the correct atom groups are close enough to react. The R groups in the active site form temporary bonds with the substrate, putting strain on its bonds, which helps the reaction proceed.
Describe the whole process of the Lock of Key Hypothesis.
- Enzymes + Substrates have specific shapes (complementary to each other)
- Active site of the enzymes is specific to the substrate.
- Bind forming enzyme-substrate complex.
- R groups of the amino acids in the active site interact with the substrate forming temporary bonds, and put strains on bonds in the substrate.
- Reaction occurs and new product(s) are made, forming an enzyme-product complex.
- A new product is released.
What is the Induced Fit Hypothesis?
The Induced Fit Hypothesis suggests that the enzyme’s active site changes shape slightly when the substrate enters, inducing strain on the substrate molecule. This change in shape lowers the activation energy required for the reaction to occur.
How does the Induced Fit Hypothesis differ from the Lock and Key Hypothesis?
Unlike the Lock and Key Hypothesis, where the enzyme’s active site is rigid, the Induced Fit Hypothesis proposes that the enzyme’s active site undergoes a slight shape change upon substrate binding, which helps weaken bonds in the substrate and lowers activation energy.
