book- chapter 3

• Metabolism is the sum of all chemical reactions that take place in cells, including catabolic and anabolic reactions
• Catabolic metabolism involves breaking down large molecules into smaller ones, such as in digestion
• Anabolic metabolism involves building up small molecules into larger ones, like in protein synthesis
• Catabolic reactions release energy, while anabolic reactions require energy
• Nutrients are substances in food used for growth, repair, and maintaining the body, including water, carbohydrates, lipids, proteins, minerals, and vitamins
• Carbohydrates are the main source of energy for cells, with simple sugars like glucose used in cellular respiration
• Carbohydrates always contain carbon, hydrogen, and oxygen, with twice as many hydrogen atoms as oxygen atoms
• Monosaccharides are single-unit sugars like glucose, fructose, and galactose
• Disaccharides are two simple sugars joined together, such as sucrose, maltose, and lactose
• Polysaccharides are large numbers of simple sugars joined together, like glycogen, cellulose, and starch
• Lipids, including fats and oils, are important energy sources broken down to fatty acids and glycerol
• Proteins are made up of amino acids and are essential for enzyme production and structural materials in the body
• Enzymes are biological catalysts that speed up chemical reactions by lowering activation energy and are specific to particular reactions
• Enzymes have an active site that binds with a substrate to form an enzyme-substrate complex
• Factors affecting enzyme activity include enzyme concentration, substrate concentration, temperature, and pH
• Enzymes have an optimal temperature range for maximum impact on reaction rate, typically between 30°C to 40°C
• Enzymes are sensitive to pH levels and require specific ions or non-protein factors for optimal function
• Enzymes:

  • Many enzymes require the presence of certain ions or non-protein molecules before they will catalyse a reaction, called cofactors
  • Cofactors change the shape of the active site so that the enzyme can combine with the substrate
  • Without a cofactor, the enzyme molecule is intact but cannot function
  • Some cofactors are non-protein organic molecules, known as coenzymes
  • Many vitamins function as coenzymes
  • Enzyme inhibitors are substances that slow or stop the enzyme's activity
  • Inhibitors may be used by cells to control reactions so that products are produced in specific amounts
• • Many drugs are enzyme inhibitors
• Factors affecting enzyme activity:

  • Temperature
  • pH
  • Concentration of both substrate and enzyme
  • Removal of products
  • Presence of cofactors, coenzymes, and enzyme inhibitors
• Glycolysis:

  • First phase in the breakdown of glucose, does not require oxygen
  • Glucose is broken down to two molecules of pyruvate
  • If no oxygen is available, pyruvate is converted to lactic acid by fermentation
  • Anaerobic respiration allows cells to produce some energy in the absence of oxygen
  • Anaerobic respiration important during vigorous physical activity
• Aerobic respiration:

  • Requires oxygen
  • Pyruvate produced from glycolysis is completely broken down to carbon dioxide and water
  • Occurs in the mitochondria of the cell
  • ATP is produced during the conversion of pyruvate to acetyl CoA and in the citric acid cycle
  • Electron transport system uses oxygen and results in the formation of water
  • Aerobic respiration releases about 95% of the energy needed to keep a cell alive
  • Mitochondria are known as the powerhouses of the cell
• ATP:

  • Adenosine triphosphate
  • Used to transfer energy between cellular respiration and processes in the cell requiring energy
  • ATP is formed when an inorganic phosphate group is joined to a molecule of adenosine diphosphate (ADP)
  • ATP can be used to transfer energy released in cellular respiration to processes in the cell that require energy
• Energy use by the cell:

  • ATP transfers energy produced in catabolic reactions to anabolic reactions that require energy
  • ATP transfers energy from reactions that release energy to reactions that require energy
• Catabolic reaction:

  • Involves breaking down large molecules into smaller ones
  • Releases energy

  Anabolic reaction:

  • Involves combining small molecules to make larger ones
  • Requires energy
• Cells use energy in five ways:

  • Movement
  • Active transport
  • Nerve impulses
  • Cell division
  • Growth
• Energy is released when ATP forms ADP because:

  • ATP is able to store energy in the bond between adenosine diphosphate (ADP) and the third phosphate group
  • This energy can be released when needed
• Approximately 60% of the energy produced during cellular respiration is released as heat. Discuss whether this energy is 'waste':

  • Heat energy is not 'waste' as it helps maintain body temperature
  • Heat energy is also used in various metabolic processes
• Cells that require a large amount of energy contain a lot of mitochondria because:

  • Mitochondria are the powerhouse of the cell and produce ATP through cellular respiration
  • More mitochondria means more ATP production for energy-demanding processes
• Optimal temperature for trypsin activity:

  • Determined through an experiment involving trypsin, milk powder solution, and different temperatures
  • Results are recorded and shared with the class
• Metabolism involves all the chemical reactions in a cell:

  • Includes catabolic and anabolic reactions
  • Nutrients from food are used in metabolism
• Enzymes increase the rate of chemical reactions by:

  • Lowering the activation energy
  • Forming enzyme-substrate complexes
• Factors affecting enzyme activity:

  • Concentration of enzyme and substrate
  • Removal of the product
  • Temperature, pH, presence of cofactors or enzyme inhibitors
• Cellular respiration involves:

  • Glucose being broken down to release energy
  • ATP storing energy in the bond between ADP and the third phosphate group
• Glycolysis is the first stage of cellular respiration:

  • Glucose forms two pyruvate molecules and two ATP molecules
  • Does not require oxygen
• In the presence of oxygen, pyruvate undergoes aerobic respiration:

  • Forms acetyl CoA before entering the citric acid cycle and electron transfer system
  • Up to 36 ATP molecules are produced
• Only 40% of the energy produced during cellular respiration is stored in ATP:

  • Remaining 60% is released as heat
  • ATP is used in various cellular processes
• Adenosine triphosphate (ATP) is able to store energy in the bond between ADP and the third phosphate group:

  • Energy can be released when needed for cellular processes
• Metabolism is the sum of all chemical reactions that take place in cells, including catabolic and anabolic reactions
• Catabolic metabolism involves breaking down large molecules into smaller ones, such as in digestion