Biology

  • Created by: AOconnor
  • Created on: 14-05-18 17:21
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  • Biology
    • Prokaryotes
      • Bacterial cells
        • Simpler structures than eukaryotes
        • Role of mitochondria and chloroplasts taken over by cytoplasm
        • Flagella are tail like structures that help the bacterium move by rotating
        • Plasmids are loops of DNA that can be transferred from one cell to another
          • Allow bacterial cells to move genes from one cell to another
            • Can be used in genetic engineering
          • Can replicate independently of chromosomal DNA
        • Chromosomal DNA is found as one long, looped chromosome in cytoplasm since there is no nucleus
        • Cell wall provides structural support but isn't made of cellulose
    • Eukaryotes
      • Plant Cell
        • Cell wall provides structural support
          • Made of cellulose which can be made using glucose from photosynthesis
        • Vacuole stores cell sap, which supports the cell
        • Chloroplasts contain pigment called chlorophyll which absorbs sunlight
      • Animal cell
        • Cell membrane controls what passes in/out of cell
        • Nucleus stores genetic material controls activity of cell
        • Cytoplasm is the site of many chemical reactions
        • Mitochondria is site of respiration
        • Ribosomes is site of protein synthesis
    • Transport
      • Osmosis
        • Movement of water down concentration gradient (high to low) across partially permeable membrane
          • Practical
            • Potatoes used to measure effect of sugar solutions on plants
            • Cut cylinders of potato and measure mass
              • Place cylinders in different sugar solutions
                • After 30 mins remove cylinders and measure mass
            • Variables
              • Control: temperature, length of time cylinders left in solution and volume of solution
              • Independent: concentration of sugar solutions
              • Dependent: Change in mass of potatoes
      • Active transport
        • Movement of substance against concentration gradient (low to high)
          • Requires energy from respiration
      • Diffusion
        • Net movement of particles down a concentration gradient (high to low) until evenly spread out
          • Factors affecting diffusion
            • Concentration gradient
            • Temperature
            • Surface area of membrane
    • Digestion
      • Enzymes
        • Catalyse breakdown of large insoluble food molecules into smaller soluble molecules
          • Properties
            • Large proteins
            • Have active site
            • Catalyse specific reaction
            • Work best at optimum pH and temperature
          • Types
            • Amylase
              • Breaks down starch into sugar (maltose)
              • Produced in salivary gland and pancreas
            • Protease
              • Breaks down protein into amino acids
              • Produced in stomach, pancreas and small intestine
            • Lipase
              • Breaks down fats into fatty acids and glycerol
              • Produced in small intestine and pancreas
          • Tests for substances
            • Glucose
              • Benedict's reagents added to food molecule with water and heated
                • If present goes red
            • Protein
              • Biuret reagents added
                • If present goes purple
            • Lipids
              • Iodine solution added
                • If present goes black/blue
      • Bile
        • Produced in liver and stored in gall bladder
        • Alkaline so it neutralises HCL in stomach
          • Optimises conditions for lipase to breakdown fats and increases rate of breakdown
        • Emulsifies fat into small droplets (increasing surface area for enzymes to work on
          • Optimises conditions for lipase to breakdown fats and increases rate of breakdown

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