Enzymes

Summary

Mr. Andersen's Biology Essentials video on enzymes explains their role in speeding up reactions without being consumed. Focusing on catalase, he describes how it breaks down hydrogen peroxide into water and oxygen at an incredible rate. The video delves into enzyme structure, activation, and inhibition, highlighting the importance of cofactors and coenzymes. He also covers competitive and allosteric inhibition, and discusses factors affecting reaction rates, such as enzyme concentration, temperature, and pH. The enzyme lab experiment with catalase in yeast is also detailed.

Takeaways

• 🧪 Enzymes are chemicals that speed up reactions without being consumed in the process.
• 🧬 Catalase is an enzyme found in almost all living cells that breaks down hydrogen peroxide into water and oxygen.
• ⚛️ The balanced chemical equation for catalase's reaction is 2 H2O2 → 2 H2O + O2.
• 🚀 Catalase works at an incredible rate, breaking down 40 million hydrogen peroxide molecules every second.
• 🔑 Enzymes have an active site where substrates fit, similar to a key fitting into a lock.
• 🔄 Enzyme activity can be regulated through activation or inhibition to control chemical reactions.
• 🛑 Inhibition can be competitive (blocking the active site) or allosteric (changing the enzyme's shape).
• 🍃 Enzymes are crucial for processes like photosynthesis and cellular respiration, where they help speed up each step.
• ⚙️ Cofactors (inorganic) and coenzymes (organic) are necessary for some enzymes to function properly.
• 🌡️ Reaction rates of enzymes can be affected by factors such as enzyme concentration, temperature, and pH.

Q & A

What are enzymes and how do they function in chemical reactions?

Enzymes are chemicals that aren't consumed in a reaction but can speed up a reaction. They work by lowering the activation energy required for a reaction, allowing it to proceed more quickly.

What is catalase and what role does it play in cells?

Catalase is an enzyme found in almost all living cells, especially eukaryotic cells. It breaks down hydrogen peroxide (H2O2) into water (H2O) and oxygen (O2), preventing the buildup of hydrogen peroxide which can damage cells.

Why is hydrogen peroxide harmful to cells?

Hydrogen peroxide is harmful because it can damage and kill cells, especially at high concentrations. It is a byproduct of various chemical reactions in the cell and must be broken down quickly to prevent cellular damage.

Describe the balanced chemical equation for the breakdown of hydrogen peroxide by catalase.

The balanced chemical equation for the breakdown of hydrogen peroxide by catalase is 2 H2O2 → 2 H2O + O2. This reaction converts two molecules of hydrogen peroxide into two molecules of water and one molecule of oxygen.

What is the significance of the active site in an enzyme?

The active site is a region within the enzyme where the substrate fits. It is crucial for the enzyme's function as it allows the substrate to bind and undergo a chemical reaction facilitated by the enzyme.

How do enzymes lower the activation energy of a reaction?

Enzymes lower the activation energy by providing an active site where substrates can be brought together in the correct orientation to react, often tugging on the substrate to facilitate the reaction and making it easier for the chemical bonds to break.

What are cofactors and coenzymes, and how do they assist enzymes?

Cofactors are inorganic chemicals that help enzymes function, such as heme. Coenzymes are organic molecules, like thiamine (vitamin B1), that assist enzymes. Both are required for enzymes to be active and perform their catalytic functions.

What is competitive inhibition in the context of enzyme activity?

Competitive inhibition occurs when an inhibitor molecule binds to the active site of an enzyme, preventing the substrate from binding. This blocks the enzyme's activity because the substrate cannot fit into the active site.

What is allosteric inhibition and how does it differ from competitive inhibition?

Allosteric inhibition involves an inhibitor binding to a different site on the enzyme, not the active site. This binding changes the shape of the enzyme and its active site, preventing the substrate from binding. This differs from competitive inhibition, which directly blocks the active site.

How can the rate of a chemical reaction be measured in an enzyme lab?

The rate of a chemical reaction can be measured by either the amount of reactants consumed or the amount of products formed. In the enzyme lab described, the rate is measured by the amount of oxygen produced when hydrogen peroxide is broken down by catalase.