2.4 Enzymes (part 1)
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Living things have thousands of different chemical reactions going on inside them all of the time. Chemical reactions inside cells are known as metabolic reactions (the sum of metabolic reactions within a cell is known as the metabolism of that cell). Metabolic reactions need to be controlled, so that the reactions produce the correct quantity of desired substances. Enzymes control the rates of reactions and they are biological catalysts. A catalyst is a chemical that speeds up the rate of a reaction without being used up in the reaction. As the catalyst is not used up in the reaction, it is available after the reaction to catalyse more reactions.
A cell has hundreds of different chemical reactions that occur and each reaction requires a different catalyst (enzyme). The nucleus of cells contains genes, which control the rate of production of enzymes, which catalyse reactions in the cytoplasm. The activities of a cell are dependent on what enzymes it makes. The enzymes that it makes are dependent on what genes are working in its nucleus. Enzymes are made from proteins.
A cell has hundreds of different chemical reactions that occur and each reaction requires a different catalyst (enzyme). The nucleus of cells contains genes, which control the rate of production of enzymes, which catalyse reactions in the cytoplasm. The activities of a cell are dependent on what enzymes it makes. The enzymes that it makes are dependent on what genes are working in its nucleus. Enzymes are made from proteins.
Gene -> Proteins/ Enzymes -> Catalyst Reactions
How do Enzymes Work?
Most of the chemical reactions that occur in a cell involve the joining together or the splitting up of chemicals. The molecule that an enzyme acts on is called a substrate. The enzyme has a unique shape that fits onto the substance involved in the reaction. This section of the enzyme is known as the active site. The active site of an enzyme will likely only be the correct shape for one reaction. The substrate fits into the active site of the enzyme and attaches itself to it. The reaction then takes place and the products are formed (the reaction may be a joining or separating of substances). When the substrate is attached to the active site, a lower amount of energy is needed to start off the chemical reaction, thus allowing the products to be produced more easily. After the products have been produced, the product(s) is (are) released and the catalyst is free to catalyse another reaction.
Most of the chemical reactions that occur in a cell involve the joining together or the splitting up of chemicals. The molecule that an enzyme acts on is called a substrate. The enzyme has a unique shape that fits onto the substance involved in the reaction. This section of the enzyme is known as the active site. The active site of an enzyme will likely only be the correct shape for one reaction. The substrate fits into the active site of the enzyme and attaches itself to it. The reaction then takes place and the products are formed (the reaction may be a joining or separating of substances). When the substrate is attached to the active site, a lower amount of energy is needed to start off the chemical reaction, thus allowing the products to be produced more easily. After the products have been produced, the product(s) is (are) released and the catalyst is free to catalyse another reaction.
Why are Enzymes Needed?
Enzymes are needed in cells because the temperature in cells is too low for a sufficient amount of chemical reactions to take place to support life. Therefore, an enzyme is needed to increase the rate of reactions, thus allowing a sufficient quantity of reactions to take place to support life. The cells in the human body are at a temperature of 37 °C, which produces too few reactions.
Enzymes are needed in cells because the temperature in cells is too low for a sufficient amount of chemical reactions to take place to support life. Therefore, an enzyme is needed to increase the rate of reactions, thus allowing a sufficient quantity of reactions to take place to support life. The cells in the human body are at a temperature of 37 °C, which produces too few reactions.