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
• Other examples


  • Skin
  • Teeth
  • Lungs
  • Spleen
  • Bones
  • Testes
  • Immune system
  • Nervous system
  • Respiratory system
  • Endocrine system
  • Urinary system
• 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 catalyzing a particular chemical reaction
• How enzymes work


  1. Enzyme has an active site with a unique shape

  2. Substrate fits into active site

  3. Enzyme speeds up the chemical reaction
• Substrate


  Reactant in a chemical reaction
• Products


  Smaller pieces that a substrate is broken into
• Enzymes speed up chemical reactions without being consumed or changed in the process
• Lock and key model


  Original model where substrate had to fit perfectly into active site
• Induced fit model


  More realistic model where enzyme changes shape slightly to better fit the substrate
• The active site of an enzyme is complementary to the substrate
• The induced fit model is like putting your hand into a rubber glove - the glove molds to your hand
• 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
• 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
• Optimal pH


  pH at which enzyme works best
• Most enzymes in our body work best at neutral pHs of around 7
• Enzymes that work in the stomach have an optimal pH of around 2 to function in the acidic environment
• There is a learning platform where you can watch all the videos, practice what you've learned with questions, and keep track of your progress for both the sciences and maths
• Biological molecules/nutrients


  Carbohydrates, lipids, proteins, vitamins, mineral ions, fiber, water
• Foods normally have a mix of different nutrients, not just one
• Carbohydrates


  Found in starchy foods, fruits, vegetables; provide energy
• Lipids


  Fats and oils; provide energy, insulate, protect organs
• Proteins


  Found in nuts, seeds, meat, fish, legumes; building blocks for growth and repair
• Vitamins


  Organic molecules made by living organisms; needed in small amounts
• Vitamin A


  • Found in liver, leafy vegetables; for vision, skin, hair
• Vitamin D


  • Found in eggs, oily fish; helps absorb calcium
• Minerals


  Inorganic, simple molecules; needed in small amounts
• Calcium


  • Found in dairy, leafy vegetables; for strong bones
• Iron


  • Found in red meat, spinach, beans; component of hemoglobin