Biology Chapter: Functions of Enzymes

Function of Enzymes

• Enzymes speed up chemical reactions by acting as biological catalysts.
• They can break down large molecules into smaller ones, known as catabolism.
  • Examples: Starch breakdown into maltose, Maltose breakdown into glucose, Protein breakdown into amino acids, and Lipids breakdown into glycerol and fatty acids.
• Enzymes can also build up large molecules from smaller ones, also known as anabolism.
  • Examples: Joining glucose molecules to form Maltose, multiple glucose molecules joining to make Glycogen (in animal cells), and multiple glucose molecules joining to form starch (in plant cells).

Role of Enzymes in Chemical Reactions

• Enzymes are reusable and can catalyze multiple reactions.
• Enzymes lower the activation energy of a reaction, making it easier for the reaction to occur.

Effect of Temperature on Enzyme Activity

• Enzymes have an optimal temperature for maximum activity.
• Below optimal temperature, enzyme activity increases as temperature increases due to an increase in kinetic energy.
• Above optimal temperature, enzyme activity decreases and eventually stops due to enzyme denaturation.

Denaturation

• Denaturation is the loss of an enzyme's shape and function.
• Changes in the shape of the active site prevent substrates from binding.

Effect of pH on Enzyme Activity

• Each enzyme has an optimal pH at which it functions best.
• The pH affects the shape of the active site, influencing substrate binding and enzyme activity.

Examples of Enzyme Activity at Different pH

• Pepsin, found in the stomach, works best at acidic pH (pH 1.5).
• Amylase, present in saliva, works best at neutral pH (pH 7).
• Lipase, located in the small intestine, works best at alkaline pH (pH 8).

The Role of Enzymes in Seed Germination

• Seed germination involves the development of a seed into a new plant.
• Dry broad beans contain stored food reserves (starch, protein, lipids, and enzymes) in the cotyledons.

Steps of Seed Germination

• Absorption of water: This activates enzymes and initiates germination.
• Amylase converts starch to maltose: This hydrolysis reaction requires water and releases energy for the embryo.
• Maltose is converted to glucose: This provides energy for embryo growth.
• Glucose diffuses to cells: This fuels respiration and energy production.
• Phloem transports glucose and amino acids: This distributes nutrients from the cotyledon to the growing embryo.
• Protease breaks down protein to amino acids: This provides building blocks for embryo growth.

Investigations

• Iodine solution is used to detect starch due to its color change from yellow to blue-black in the presence of starch.
• The effect of amylase on starch can be observed by comparing the color changes in test tubes with and without amylase.
  • Amylase breaks down starch, resulting in a gradual color transition from blue-black to light blue and finally yellow-brown.
  • Test tubes without amylase will remain blue-black due to the presence of intact starch.

Explore the essential functions of enzymes in biological processes through this quiz. Understand how enzymes act as catalysts, their roles in catabolism and anabolism, and the impact of temperature on enzyme activity. Test your knowledge on these crucial biochemical components.