Organisation

• Organelles

  Also called subcellular structures, the parts that make up a cell like the nucleus, ribosomes, and mitochondria
• Organelles

  • Each individual organelle has a specific role to play
  • When combined, multiple organelles will form a single cell
• Cells

  Come in all sorts of shapes and sizes and contain different combinations and numbers of organelles
• Specialized cells

  Different types of cells like epithelial cells, muscle cells, and glandular cells
• Tissues


  A group of similar cells that work together to carry out a particular function
• Tissues


  • Epithelial tissue
  • Muscle tissue
  • Glandular tissue
• Organs


  A group of different tissues that work together to perform a particular function
• Organs

  • Stomach
  • Pancreas
  • Liver
• Organ systems


  A group of organs that work together to perform a particular function
• Organism


  The highest level, with multiple organ systems working together
• Enzymes


  Catalysts made by living organisms
• Enzymes

  • They are large proteins made up of long chains of amino acids
  • They can fold into different shapes, each shape being a unique enzyme that catalyzes a particular chemical reaction
• How enzymes work


  1. Enzyme has an active site with a unique shape complementary to the substrate

  2. Substrate binds to active site

  3. Enzyme catalyzes the reaction

  4. Products are released
• Substrate

  Reactant in a biological chemical reaction
• Products

  Smaller pieces that a substrate is broken into during a reaction
• Catalyst

  A substance that increases the speed of a chemical reaction without being changed or used up in the process
• Enzymes are a type of catalyst made by living organisms
• Enzymes speed up chemical reactions without being consumed or permanently altered
• If the substrate doesn't fit the active site of the enzyme

  The reaction won't be catalyzed
• Lock and key model

  • Substrate has to fit perfectly into the active site of the enzyme, like a key in a lock
• Induced fit model

  • The enzyme changes shape slightly as it binds to the substrate, allowing them to fit together more perfectly
• The induced fit model is a more realistic description of how enzymes work
• Enzymes allow living cells to carry out a huge number of chemical reactions every second
• Most chemical reactions are naturally quite slow
• Increasing temperature

  Can increase the rate of chemical reactions
• High temperatures can damage cells and speed up unwanted reactions
• Catalysts provide a better way to increase the speed of chemical reactions
• How temperature and pH affect the functioning of enzymes and the rate of enzyme controlled reactions

  1. Increase in temperature increases rate of reaction

  2. Rate starts to drop rapidly at high temperatures due to bonds breaking and active site changing shape

  3. Enzyme becomes denatured at high temperatures

  4. Optimal temperature is the temperature at which rate of reaction is highest
• Denatured


  Enzyme cannot bind to substrate and catalyze reaction anymore due to active site changing shape
• Foods normally have a mix of different nutrients in them not just one
• Optimal temperature


  Temperature at which rate of reaction is highest
• How pH affects enzymes

  1. If pH gets too high or too low, it will lower the rate of reaction

  2. At first, active site just changes a bit so substrate can still fit but less well

  3. Soon, active site changes shape so much that substrate can't fit at all and enzyme becomes denatured
• Main nutrient groups that make up the large majority of our diet

  • Carbohydrates
  • Lipids
  • Proteins
• Optimal pH


  pH at which enzyme works best
• Most enzymes in our body work best at neutral pHs of around 7
• Carbohydrates


  Found most in starchy foods like bread, pasta and potatoes, as well as in fruits and vegetables. Provide us with most of the energy we need to carry out chemical reactions and move around.
• Lipids


  Fats and oils. Fats are lipids that are solid at room temperature, oils are lipids that are liquid at room temperature. Found in oily fish, nuts, seeds, dairy products and avocados. Provide energy and act as a longer term store of energy. Also insulate us and protect our organs.
• Enzymes that work in the stomach have an optimal pH of around 2 to function in the acidic environment
• Proteins


  Found in nuts, seeds, meat, fish, legumes like lentils and beans. Act as building blocks for growth and repair of damaged tissue. Can also be used for energy in emergencies.
• Enzymes


  Essential for helping us break down the large molecules that we eat into the much smaller soluble molecules that we can absorb through our intestinal lining