Biology chapter 3 gcse

• Hierarchy of organization:

  • Cell
  • Tissue
  • Organ
  • Organ system
  • Organism
• Amylase is produced in the salivary glands, pancreas, and small intestine; works in the mouth and small intestine
• Enzymes and digestion:

  • Glands in the stomach produce hydrochloric acid, which is the ideal environment for protease
  • The acid also kills pathogens
  • Bile is added as it travels through the small intestine
  • Bile is made in the liver and stored in the gallbladder, which is alkaline to neutralize the stomach
  • Bile emulsifies fat, creating a larger surface area
  • The alkaline conditions and large surface area increase the rate of fat breakdown by lipase
• Factors affecting enzyme reaction:

  • The rate of an enzyme-catalyzed reaction is affected by pH and temperature
  • When an enzyme is denatured, it won't fit the next substrate because the active site is ruined
  • An increase in temperature initially increases the rate of an enzyme-catalyzed reaction, but after 40°C, denaturation occurs, and the rate of reaction drops dramatically
  • The rate of reaction is fastest at the optimum temperature
• Enzyme-substrate complex:

  • Enzymes reduce the activation energy required for a reaction to take place
• Enzymes:

  • Proteins carry out many different functions, such as antibodies in the immune system that destroy pathogens, muscles, and enzymes
  • Enzymes are biological catalysts
  • There are thousands of different enzymes, each catalyzing a different reaction
• Required practical 5:

  • Iodine: starch test, changes color from orange to blue/black in the presence of starch
  • Benedicts: glucose test, changes color from blue to brick red (or green/orange for lower concentrations) in the presence of glucose
  • Biuret: protein test, changes color from light blue to pale purple in the presence of protein
  • Sudan 3: lipids test, changes color to milky white or forms a red layer in the presence of lipids (e.g., cheese, butter, oils)
• Tissue: a group of cells with a similar structure working together
• Organ system: a group of organs working together for a particular function
• Organs: a group of tissues working together for a particular function
• Pancreas: produces enzymes which travel into the intestine via the pancreatic duct
• Stomach: acid is added and enzymes digest food
• Liver: produces bile which emulsifies fat and neutralises the stomach acid
• Small intestine: enzymes digest food and where absorption of soluble products of digestion occurs
• Salivary glands: produces enzymes that are mixed with food as it is chewed
• Large intestine: absorbs water from undigested food producing faeces
• Proteins: long chains of amino acids
• Metabolism: the sum of all the reactions in the cell or body
• Catalyst: a substance that changes the rate of a chemical reaction
• Enzyme: a biological catalyst
• Enzyme-substrate complex: the enzyme and substrate bound together
• Activation energy: the energy needed for the chemical reaction to take place
• Active site: the special site in the structure of the enzyme where the substrate binds
• Ribosome - The site where protein synthesis occurs
• The nucleus is the control centre of the cell, containing DNA which controls all activities within the cell.