BIOLOGI SMA Kelas 12 - Metabolisme Part 1 (Enzim) | GIA Academy

Summary

This video script from Kia Academy YouTube channel explores the concept of metabolism, focusing on enzymes as biological catalysts. It explains how enzymes speed up chemical reactions in the body without altering their own structure, and delves into the different types of enzymes, their mechanisms of action, and factors affecting their activity, such as temperature, pH, and the presence of activators and inhibitors.

Takeaways

• 🏃‍♂️ Physical activities, such as exercise, help in maintaining a fit body, while continuous sedentary activities like sitting and eating can lead to fat accumulation and weight gain.
• 🔬 Metabolism is a series of chemical reactions occurring in living organisms' cells, converting nutrients into energy for sustaining life.
• 🌟 Enzymes are biological catalysts that speed up these metabolic reactions without undergoing any chemical changes themselves.
• 📊 Enzymes reduce the activation energy required for a reaction, making the process more efficient and faster.
• 🤔 Enzymes can be classified into two types based on their composition: simple enzymes (made of protein) and complex enzymes (holoenzymes) which consist of protein and non-protein components.
• 🧬 Holoenzymes are composed of an apoenzyme (protein part) and a coenzyme or cofactor, which are essential for the enzyme's activity.
• 🔍 The active site of an enzyme is the specific part where the substrate binds, and the allosteric site is where regulators like activators and inhibitors can bind.
• 🔄 Enzymes are highly specific, meaning they only catalyze reactions of certain substrates, and their activity is influenced by factors like pH and temperature.
• 🌡️ Each enzyme has an optimal temperature and pH at which it works best, and deviations from these can lead to reduced activity or denaturation.
• 💡 Theories explaining enzyme function include the lock-and-key model, where the enzyme's active site fits the substrate like a key in a lock, and the induced fit model, where the enzyme's shape changes upon substrate binding.

Q & A

What is metabolism and why is it important in our body?

Metabolism is a series of chemical reactions occurring within the cells of living organisms, converting food into energy for sustaining life. It is crucial as it processes nutrients from food to produce energy and maintain bodily functions.

How do enzymes function as catalysts in metabolic processes?

Enzymes function as biological catalysts, speeding up biological reactions without undergoing any chemical changes themselves. They lower the activation energy required for a reaction, making the process faster and more efficient.

What is the role of enzymes in lowering the activation energy in reactions?

Enzymes reduce the activation energy needed for a reaction by providing an alternative reaction pathway with a lower energy barrier. This allows the reaction to proceed more quickly with less free energy required.

How are enzymes classified based on their composition?

Enzymes are classified into two types based on their composition: simple enzymes, which consist only of protein, and complex enzymes, also known as holoenzymes, which consist of protein components and non-protein components such as coenzymes and cofactors.

What are the components of a holoenzyme?

A holoenzyme consists of an apoenzyme (the protein component), a coenzyme (an organic compound like a vitamin), and cofactors (inorganic compounds like metal ions).

What is the specificity of enzymes in catalyzing reactions?

Enzymes are highly specific in their action, meaning they only affect certain substrates. The active site of an enzyme is selective for the chemical structure of the substrate it catalyzes.

How do temperature and pH affect enzyme activity?

Temperature and pH can significantly influence enzyme activity. Each enzyme has an optimal temperature and pH at which it functions best. Deviations from these optimal conditions can lead to reduced activity or denaturation of the enzyme.

What are the two theories that explain how enzymes work?

The two theories explaining enzyme function are the lock and key model, which suggests that the enzyme's active site and substrate fit together perfectly, and the induced fit model, which proposes that the enzyme's active site changes shape to fit the substrate.

What are activators and inhibitors, and how do they affect enzyme activity?

Activators are substances that enhance or accelerate enzyme reactions, such as salts and metal ions. Inhibitors, on the other hand, are substances that slow down or prevent enzyme reactions. They can be competitive (binding at the active site) or non-competitive (binding at an allosteric site).

How do substrate concentration and enzyme concentration influence the rate of a reaction?

The rate of a reaction increases with increasing substrate concentration, provided the enzyme concentration is constant. However, if the enzyme concentration is too low relative to the substrate concentration, the reaction may proceed slowly, and some substrates may remain uncatalyzed.

What is the difference between competitive and non-competitive inhibitors?

Competitive inhibitors bind to the active site of an enzyme, competing with the substrate for binding, and can be overcome by increasing substrate concentration. Non-competitive inhibitors bind to an allosteric site, altering the enzyme's shape and preventing substrate binding, and their effect cannot be reversed by increasing substrate concentration.