enzymes worksheet
1) what is a catalyst?
2) what is an enzyme?
3) what is the active site and what is its job?
4) what is a substrate?
5) what is the product?
6) explain how an enzyme works using the terms from questions 1 – 5.
7) what is denaturing and what causes it to occur?
8) what 4 things can affect the way enzymes work? explain how each thing affects an enzyme.
9) how can a lock and key be used to describe an enzyme?

Question

Accepted Answer

To answer these questions, we'll go through each one with the appropriate scientific concepts related to enzymes (a topic in Biology, a subfield of Natural Science).

### Question 1: What is a catalyst?
# Brief Explanations:
A catalyst is a substance that increases the rate of a chemical reaction by lowering the activation energy (the energy needed to start the reaction) without being consumed or permanently altered in the process. This allows reactions to occur more quickly or under milder conditions.
# Answer:
A substance that increases the rate of a chemical reaction by lowering the activation energy, without being consumed in the reaction.

### Question 2: What is an enzyme?
# Brief Explanations:
Enzymes are biological catalysts, typically proteins (though some RNA molecules called ribozymes also act as enzymes). They speed up chemical reactions in living organisms by lowering activation energy. Each enzyme is specific to a particular reaction or set of reactions (substrate - specific) and functions optimally under certain conditions (like specific temperature, pH).
# Answer:
A biological catalyst (usually a protein) that speeds up chemical reactions in living organisms by lowering activation energy, with high specificity for its substrate.

### Question 3: What is the active site and what is its job?
# Brief Explanations:
The active site is a specific, three - dimensional region of an enzyme (usually a pocket or groove) formed by the folding of the enzyme's protein structure. Its job is to bind to the substrate (the molecule the enzyme acts on) in a highly specific way (like a lock and key or induced fit model). Once the substrate is bound, the active site facilitates the chemical reaction, either breaking the substrate into products or joining substrates together.
# Answer:
The active site is a specific region of an enzyme (a pocket/groove in the enzyme's structure) that binds to the substrate. Its job is to facilitate the chemical reaction of the substrate (either breaking it down or combining it with other molecules) by providing an environment for the reaction to occur.

### Question 4: What is a substrate?
# Brief Explanations:
A substrate is the molecule (or molecules) upon which an enzyme acts. It is the reactant in the enzyme - catalyzed reaction. The substrate has a shape that is complementary to the enzyme's active site, allowing it to bind there and undergo a chemical change (be converted into products).
# Answer:
The molecule (or molecules) that an enzyme acts on; the reactant in an enzyme - catalyzed chemical reaction.

### Question 5: What is the product?
# Brief Explanations:
The product is the molecule (or molecules) formed as a result of the enzyme - catalyzed reaction. After the substrate undergoes a chemical change at the enzyme's active site, the resulting molecule(s) is/are called the product(s). For example, in the reaction catalyzed by amylase, starch (substrate) is broken down into maltose (product).
# Answer:
The molecule (or molecules) formed as a result of an enzyme - catalyzed chemical reaction (the result of the substrate being chemically changed).

### Question 6: Explain how an Enzyme works using the terms from questions 1 – 5.
# Brief Explanations:
1. Enzymes are biological catalysts (from Q2). A catalyst (Q1) speeds up a reaction by lowering activation energy.
2. The enzyme has an active site (Q3) that is specific to its substrate (Q4). The substrate binds to the enzyme's active site.
3. Once the substrate is bound, the enzyme facilitates the chemical reaction, converting the substrate into the product (Q5). After the reaction, the enzyme is released and can be reused, as it is not consumed in the reaction.
# Answer:
Enzymes are biological catalysts (Q2) that increase reaction rates (like a catalyst, Q1) by lowering activation energy. The enzyme has an active site (Q3) that specifically binds to its substrate (Q4). When the substrate binds to the active site, the enzyme catalyzes the reaction, converting the substrate into the product (Q5). The enzyme is then released and can catalyze more reactions.

### Question 7: What is denaturing and what causes it to occur?
# Brief Explanations:
Denaturing is the process by which an enzyme (or other protein) loses its specific three - dimensional structure, including the structure of the active site. This loss of structure causes the enzyme to lose its catalytic activity because the active site loses its specific shape needed to bind the substrate. Denaturing is caused by factors that disrupt the weak bonds (like hydrogen bonds, ionic bonds) that maintain the protein's secondary, tertiary, and quaternary structures. Common causes include high temperatures (which provide too much kinetic energy to break the bonds) and extreme changes in pH (which alter the charge distribution in the protein, disrupting ionic bonds and hydrogen bonds).
# Answer:
Denaturing is the process where an enzyme (protein) loses its specific three - dimensional structure (including the active site structure), resulting in loss of catalytic activity. It is caused by factors like high temperature (breaks bonds maintaining structure) and extreme pH (alters charge - based bonds in the protein).

### Question 8: What 4 things can affect the way enzymes work? Explain how each thing affects an enzyme.
# Brief Explanations:
1. **Temperature**:
   - At low temperatures, enzyme activity is low because the molecules (enzyme and substrate) have low kinetic energy, so there are fewer successful collisions between the enzyme's active site and the substrate.
   - At an optimal temperature (different for different enzymes, e.g., human enzymes around 37°C), enzyme activity is highest as the kinetic energy is just right for maximum successful collisions and proper active site - substrate interaction.
   - At high temperatures (above the optimal), the enzyme denatures (loses its active site structure), and activity drops sharply as the active site can no longer bind the substrate.
2. **pH**:
   - Each enzyme has an optimal pH (e.g., pepsin in the stomach works best at acidic pH ~2, trypsin in the small intestine at slightly alkaline pH ~8).
   - Deviations from the optimal pH (either too acidic or too alkaline) can cause the enzyme to denature (by disrupting bonds in the protein structure) or can alter the charge of the active site or substrate, preventing proper binding.
3. **Substrate Concentration**:
   - As substrate concentration increases, the rate of enzyme - catalyzed reaction increases (up to a point). This is because more substrate molecules mean more frequent collisions with the enzyme's active site.
   - However, once all the enzyme's active sites are occupied (saturation point), further increases in substrate concentration do not increase the reaction rate, as there are no more free active sites to bind the additional substrate.
4. **Enzyme Concentration**:
   - If substrate is in excess, increasing the enzyme concentration will increase the reaction rate. This is because more enzyme molecules mean more active sites available to bind substrate, leading to more reactions occurring per unit time.
# Answer:
1. **Temperature**: Low temp - low activity (low kinetic energy, few collisions); Optimal temp - max activity; High temp - denaturation, activity drops.
2. **pH**: Deviation from optimal pH (too acidic/alkaline) causes denaturation or charge changes, reducing activity.
3. **Substrate Concentration**: Increases rate (more collisions) until saturation (all active sites occupied), then rate levels off.
4. **Enzyme Concentration**: Increases rate (more active sites) when substrate is in excess.

### Question 9: How can a lock and key be used to describe an enzyme?
# Brief Explanations:
The lock - and - key model is a way to describe enzyme - substrate interaction. The enzyme is like a lock, with a specific - shaped active site (the "keyhole"). The substrate is like a key, with a shape complementary to the enzyme's active site (the keyhole). Just as a key can only fit into a specific lock, a substrate can only fit into the active site of a specific enzyme. Once the substrate (key) binds to the enzyme's active site (lock), the enzyme can catalyze the reaction (like the lock opening when the correct key is inserted and turned).
# Answer:
The enzyme is like a lock (with a specific - shaped active site/"keyhole"), and the substrate is like a key (with a complementary shape to the active site). Only the correct substrate (key) can fit into the enzyme's active site (lock), and when it does, the enzyme can catalyze the reaction (similar to a lock opening with the correct key).

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Question 1: What is a catalyst?

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Question 2: What is an enzyme?