Bio

• Cells

  The smallest living unit and the most basic building blocks of life
• Tissue


  A group of similar cells working together to carry out a function
• Organ


  A group of tissues working together to carry out a function
• Organ system


  Groups of organs working together
• Organism


  Multiple organ systems working together to form the whole
• Tissue example


  • Palisade tissue layer in a leaf which carries out photosynthesis
• Organ example


  • The heart which pumps blood around the body
• Organ system example


  • The nervous system
• Organism examples


  • A whole plant, a whole insect, a human
• These go in size order: cells, tissues, organs, organ systems, whole organism
• Salivary glands


  Secrete saliva that contains the enzyme amylase which digests carbohydrates
• Stomach


  Contains hydrochloric acid to kill bacteria and proteases to digest proteins
• Protease enzyme


  Breaks down proteins into amino acids
• Small intestine


  Where absorption of small molecules into the blood occurs, contains enzymes from the pancreas including lipase to digest lipids
• Lipase enzyme


  Breaks down lipids into glycerol and fatty acids
• Enzymes and their functions

  • Amylase (breaks down carbohydrates)
  • Protease (breaks down proteins)
  • Lipase (breaks down lipids)
• Lock and key mechanism

  The substrate acts like a key that fits into the active site of the enzyme which acts like a lock
• Digestive enzymes


  • Break down large insoluble molecules into small soluble molecules that can be absorbed into the blood
• Amino acids


  Small molecules absorbed that can be used to build proteins
• Glucose


  Small molecule absorbed that can be used to build other carbohydrates like glycogen or used in respiration
• Fatty acids and glycerol


  Small molecules absorbed that can be used to make lipids for energy storage or insulation
• Factors affecting enzyme action rate

  • Temperature, pH, substrate concentration, surface area
• Denatured


  The active site of the enzyme changes shape so it can no longer bind to the substrate
• Bile


  Produced by the liver, stored in the gallbladder, released into the small intestine to help digest fats through emulsification
• Emulsification


  Bile breaks down large lipid droplets into smaller ones, increasing the surface area for lipase enzymes to work on
• Bile is not an enzyme, it increases the speed of lipid digestion but does not break them down itself
• Starch test


  Add iodine, color change to blue-black indicates presence of starch
• Protein test


  Add biuret reagent, color change to purple indicates presence of protein
• Glucose test


  Add Benedict's reagent (heat), color change to brick red indicates presence of glucose
• Lipid test


  Add ethanol, then water and shake, a cloudy white emulsion indicates presence of lipids
• No color change indicates a negative result for the tests
• Independent variable


  The variable that is changed, e.g. pH, temperature, substrate concentration
• Dependent variable


  The variable that is measured, e.g. time for color change, mass/volume of product, change in pH
• Control variables


  Variables that are kept constant, e.g. volumes, concentrations, pH, temperature
• Example enzyme experiment


  • Measuring time for starch digestion by amylase at different temperatures
• Optimum temperature


  The temperature at which the enzyme works best, usually around 37°C for human enzymes
• Arteries


  Transport blood away from the heart at high pressure, have narrow lumen, thick elastic walls, and muscular walls
• Veins


  Transport blood to the heart at low pressure, have wider lumen, thinner walls, and valves to prevent backflow
• Capillaries


  Transport blood close to cells for exchange, have very narrow lumen to slow flow and thin walls for diffusion
• Blood plasma


  The liquid part of blood that contains dissolved substances being transported