Back to B2 Home
B2 B) Enzymes
B2 B) Enzymes
Living organisms have thousands of different chemical reactions going on inside them all of the time. Chemical reactions taking place inside cells are known as metabolic reactions. Metabolic reactions need to be controlled, so that the reactions produce the correct quantities of desired substances. Cells have enzymes that increase the rate of reactions in cells. Enzymes are biological catalysts.
All of the different reactions in cells require different enzymes; there is not one enzyme that catalyses all of the different reactions.
- Biological means that the enzymes have been produced by us; enzymes are proteins that have been synthesised by ribosomes.
- Catalysts have two characteristics:
- 1 – they increase the rate of reaction
- 2 – they are not used up during the reaction – after the catalyst has catalysed a reaction, it is unchanged and free to catalyse more reactions
All of the different reactions in cells require different enzymes; there is not one enzyme that catalyses all of the different reactions.
How do Enzymes Work?
There is a diagram below of an enzyme and a substrate (the substance that the enzyme is for).
There is a diagram below of an enzyme and a substrate (the substance that the enzyme is for).
Most of the chemical reactions in cells involves the joining together or the splitting up of substances; we are going to look at what happens when an enzyme splits a larger substance into two smaller substances. The substance that the enzyme is for is known as the substrate (this is the green thing on the above diagram). The enzyme has a unique shape on its surface that the subtract fits into; this section of the enzyme is known as the active site. The active site of an enzyme will only be the correct shape for one type of reaction; this is why there are many different types of enzymes in the body and not just one type.
The substrate fits into the active site of the enzyme and attaches itself to it (part 2). The reaction then takes place and the products are formed; for our example, the substrate splits into two different products (part 3). When the substrate is attached to the active site, a lower amount of energy is needed to start the reaction, which means that reactions take place more easily and the rate of reaction increases. After the reaction has taken place, the products are released (part 4). The enzyme is unchanged during the reaction, which means that it is free to catalyse more reactions; another substrate enters the active site, and the whole process starts again.
The process of the substrate attaching to the active site of the enzyme is sometimes referred to as the lock and key theory; the lock is the enzyme and the key is the substrate.
We have many different types of enzymes in the body. This is because the different reactions have different substrates, which are different shapes. These different shaped substrates require different shaped active sites, thus meaning that different reactions require different enzymes. Example of different enzymes are amylase, protease and lipase.
The process of the substrate attaching to the active site of the enzyme is sometimes referred to as the lock and key theory; the lock is the enzyme and the key is the substrate.
We have many different types of enzymes in the body. This is because the different reactions have different substrates, which are different shapes. These different shaped substrates require different shaped active sites, thus meaning that different reactions require different enzymes. Example of different enzymes are amylase, protease and lipase.
Why are Enzymes Needed?
If humans didn’t have enzymes, the temperature inside the body would be too low for a sufficient number of chemical reactions to take place to support life. Enzymes increase the rate of reaction, which produces sufficient quantities of substances – enzymes are essential for life.
If humans didn’t have enzymes, the temperature inside the body would be too low for a sufficient number of chemical reactions to take place to support life. Enzymes increase the rate of reaction, which produces sufficient quantities of substances – enzymes are essential for life.