DESCRIPTION:
Assignment Brief: In your own time, answer all the questions on the worksheet provided, ensuring that you attempt to answer all the questions (1.1, 1.2, 3.1, 3.2, 3.3, 3.4). Your answers must be fully referenced. __________________________________________________ 1.1 Distinguish the terms metabolism, anabolism and catabolism and give a range of examples 1.2 Describe the structure of ATP and explain how ATP is involved in exothermic and endothermic reactions in the cell. 2.1 Explain the lock and key and induced fit hypotheses of enzyme action 2.2 Explain the role of enzymes in metabolic processes 2.3 Interpret data relating to the effect of temperature, pH or inhibitors on enzyme activity 2.4 Explain the effect of temperature, pH and inhibitors on enzyme activity 3.1 Identify the main stages in aerobic and anaerobic respiration and the main products of each stage 3.2 Explain the importance of co-enzymes in aerobic respiration and show how the different stages of respiration are linked 3.3 Explain the difference in yield of ATP from anaerobic and aerobic respiration 3.4 Explain the concept of oxygen debt
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1.1 Distinguish the terms metabolism, anabolism and catabolism and give a range of examples:
Metabolism refers to all the chemical reactions that occur within an organism, including the breakdown of molecules for energy and the synthesis of new molecules. Anabolism is a subset of metabolism that involves the synthesis of new molecules, such as the building of proteins from amino acids or the synthesis of carbohydrates from simple sugars. Anabolic reactions require energy input, and are endothermic. Catabolism is the opposite of anabolism and refers to the breakdown of complex molecules into simpler ones, releasing energy in the process. Catabolic reactions are exothermic.
Examples of anabolic reactions include the synthesis of proteins from amino acids, the synthesis of lipids from fatty acids and glycerol, and the synthesis of nucleic acids from nucleotides. Examples of catabolic reactions include the breakdown of glucose to release energy, the breakdown of fatty acids in adipose tissue, and the breakdown of amino acids in muscle tissue.
1.2 Describe the structure of ATP and explain how ATP is involved in exothermic and endothermic reactions in the cell:
ATP, or adenosine triphosphate, is a high-energy molecule that is used to transfer energy within cells. The molecule consists of an adenine base, a ribose sugar, and three phosphates. The energy stored in ATP is in the form of the bonds between the phosphates. When the terminal phosphate bond is broken, energy is released, and the molecule becomes ADP (adenosine diphosphate). This reaction is exothermic.
ATP is involved in both exothermic and endothermic reactions in the cell. In exothermic reactions, such as catabolic reactions, the energy released when the terminal phosphate bond of ATP is broken is used to drive the reaction. In endothermic reactions, such as anabolic reactions, the energy released when the terminal phosphate bond of ATP is broken is used to drive the synthesis of new molecules.
2.1 Explain the lock and key and induced fit hypotheses of enzyme action
The lock and key hypothesis, proposed by Emil Fischer in 1894, explains the specific binding of enzymes and substrates. According to this hypothesis, enzymes have a specific active site that is complementary in shape to the substrate, similar to a lock and key mechanism. Once the substrate fits into the active site, a chemical reaction occurs, and the products are formed.
The induced fit hypothesis, proposed by Daniel Koshland in 1958, builds upon the lock and key hypothesis by suggesting that the binding of the substrate to the enzyme causes a conformational change in the enzyme, which in turn, causes the substrate to fit better into the active site. This conformational change, or induced fit, increases the specificity and efficiency of the enzyme-substrate interaction.
2.2 Explain the role of enzymes in metabolic processes
Enzymes are catalysts that speed up chemical reactions within the cell. They work by decreasing the activation energy required for a reaction to occur, making it more likely that the reactants will form products. This increases the rate of the reaction, allowing the cell to carry out its metabolic processes more efficiently. Enzymes are specific to certain reactions and substrates, and each enzyme is responsible for catalyzing a specific chemical reaction.
2.3 Interpret data relating to the effect of temperature, pH or inhibitors on enzyme activity
Enzyme activity can be affected by various factors such as temperature, pH, and inhibitors. An increase in temperature generally leads to an increase in enzyme activity
