Question

what are enzymes & what do they do?
how do enzymes actually work?
fully label these diagrams to show how enzymes work:
effect of enzymes on activation energy
draw a second line to show how enzymes affect the energy in a reaction. complete the label and add any more labels you can!
models of enzyme action

Explanation:

Part 1: What are enzymes & what do they do?

Enzymes are biological catalysts (usually proteins, some RNA) that speed up chemical reactions in cells by lowering activation energy. They are specific to substrates (reactants), bind at active sites, and aren’t consumed. They facilitate metabolic reactions (e.g., digestion, respiration) by reducing the energy needed for reactions to start, enabling them to occur efficiently at physiological temperatures.

Answer:

Enzymes are biological catalysts (typically proteins, some RNA) that speed up chemical reactions in living organisms by lowering the activation energy required for the reaction. They are specific to their substrate(s), bind at an active site, and are not consumed in the reaction. They facilitate essential metabolic processes (e.g., digestion, cellular respiration) by enabling reactions to occur efficiently at normal physiological temperatures.

Part 2: How do enzymes actually work? (Labeling the diagrams)

Left Diagram (Induced - Fit/ Lock - and - Key - like, maybe Induced Fit)

• Top Blue Shape: Enzyme (has an active site that will interact with substrate).
• Top Pink Shapes: Substrate(s) (molecules the enzyme acts on; they fit/are modified to fit the active site).
• Middle Step (Blue + Pink): Enzyme - Substrate Complex (substrate(s) bound to enzyme’s active site; enzyme may change shape slightly to better fit substrate, “induced fit”).
• Bottom Blue Shape: Enzyme (released after reaction, unchanged and reusable).
• Bottom Pink Shape: Product(s) (molecules formed after enzyme - catalyzed reaction; substrate is converted).

Middle Diagram (Another Enzyme - Substrate - Product Cycle)

• Top Orange Shape: Enzyme (active site).
• Top Pink Shape: Substrate.
• Middle Step (Orange + Pink): Enzyme - Substrate Complex.
• Bottom Orange Shape: Enzyme (reusable).
• Bottom Pink Shapes: Products (substrate is broken down into multiple products).

Bottom - Left Diagram (Models of Enzyme Action - Lock and Key/Induced Fit)

• Top Orange + Pink: Enzyme (orange) and Substrate (pink) approaching (substrate shape complementary to enzyme’s active site, or enzyme will adjust shape).
• Middle Step: Enzyme - Substrate Complex (substrate bound, enzyme may have induced fit - slight shape change to hold substrate).
• Bottom Step: Enzyme (orange) and Product(s) (pink, now modified from substrate) - enzyme is released to catalyze another reaction.

Lock - and - Key Analogy (Bottom - Middle Lock/Key Image)

• Lock: Enzyme (active site has a specific shape, like a lock’s keyhole).
• Key: Substrate (shape complementary to enzyme’s active site, like a key to a lock; only the correct “key” (substrate) fits the “lock” (enzyme)).

Part 3: Effect of enzymes on activation energy (Graph)

• Red Line (Without Enzyme): Represents the energy profile of a reaction without an enzyme. The peak is the Activation Energy (\(E_A\)) - the energy needed to start the reaction.
• White Line (With Enzyme): Draw a line parallel to the x - axis but lower than the red line’s peak. This line represents the energy profile with an enzyme. The difference between the two peaks is the reduction in activation energy caused by the enzyme.
• Labels:
• “Activation Energy (Without Enzyme)”: Peak of the red line.
• “Activation Energy (With Enzyme)”: Peak of the white line.
• “Progress of Reaction”: X - axis (from reactants to products).
• “Total Energy”: Y - axis (energy of reactants, products, and transition state).
• “Reactants”: Energy level at the start of the red line.
• “Products”: Energy level at the end of the red line (and white line; enzymes don’t change reactant or product energy, only activation energy).
• “Transition State”: The highest energy point of each line (peak) - the unstable intermediate state during the reaction.

Enzymes lower the activation energy (\(E_A\)) by stabilizing the transition state, making it easier for reactants to become products. So the “with enzyme” line has a lower peak (less \(E_A\)) than the “without enzyme” line.