B4 Mindmap

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  • Created by: tom1000
  • Created on: 14-04-16 17:46
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  • B4
    • Cell structure and function
      • Plant and animal cells have similarities and differences
        • Most animal and plant cells have parts
          • Nucleus
          • Cytoplasm
          • Cell membrane
          • Mitochondria
        • Plant cells also have a few extra things animal cells don't have
          • Rigid cell wall
            • Made of cellulose, it supports the cell and strengthens it.
          • Vacuole
            • Contains cell sap, a weak solution of sugar and salts
          • Chloroplasts
            • where the reactions for photosynthesis take place. Contains chlorophyll and the enzymes needed for photosynthesis
      • Bacteria have a simple cell structure
        • They don't have a nucleus
          • They have a circular molecule of DNA which floats around in the cytoplasm.
        • They don't have mitochondria either
          • But they can still respire anaerobically
    • Enzymes
      • Enzymes are proteins that  speed up chemical reactions
      • Enzymes are very specific
        • A substrate is a molecule that is changed in a reaction
        • Every enzyme has an active site, it's where the substrate joins onto the enzyme
        • Each enzyme only speeds up one reaction, as it's active site is only specific to one substrate.
        • The name for how the enzyme only fits one substrate is called the lock and key model
      • Enzymes need the right temperature and pH
        • They have to be at a specific temperature and in specific conditions to work at their optimum
        • Changing the temperature changes the rate of an enzyme controlled reaction
        • if you increase the temperature, activity will increase at first, but after a certain point, the bonds in the enzyme will break and it will denature
        • When an enzyme denatures, it's bonds break and so it changes shape so the substrate doesn't fit the active site any more
        • All enzymes also have an optimum pH and if that changes too much, it will denature aswell
    • Aerobic respiration
      • Respiration
        • Respiration is a series of chemical reactions that release energy by breaking down large food molecules. it happens in living cell
      • The energy released in respiration is used to power some of the chemical reactions that happens in cells, e.g. the reactions involved in;
        • Movement - Energy is needed to make muscles contract
        • Active transport - This process uses energy to move some substances in and out of cells
        • Synthesis of large molecules
          • Lots of large molecules (polymers) are made by joining smaller molecules together
          • Glucose is joined together to make things like starch and cellulose in plant cells
          • In plant cells, animal cells and microorganisms, glucose and nitrogen are joined together to make amino acids. the amino acids are joined together to make proteins
      • Aerobic respiration needs a lot of oxygen
        • The aerobic basically means 'with oxygen'
        • It releases more energy per molecule of glucose than anaerobic respiration
        • This type of respiration happens most of the time
        • Aerobic respiration happens in animal and plant cells, and microorganisms
      • The word and symbol equations for aerobic respiration
        • Glucose + oxygen => carbon dioxide + water (+energy released)
        • C6 H12 O6 + 6 O2 => 6 CO2 +6 H2O (+energy released)
    • Anaerobic respiration
      • Doesn't use oxygen
      • Takes place in animal and plant cells and some microorganisms when there is very little or no oxygen
        • Human cells - when you do really vigorous exercise, your body can't supply enough oxygen to your muscle cells for aerobic respiration so they just respire anaerobically
        • Plant cells - if the soil a plant's growing in becomes waterlogged there won't be any oxygen getting to the roots so the root cells will have to respire anaerobically
        • Bacterial cells - bacteria can get under your ski n through puncture wounds caused by things like nails. there's very little oxygen there so only the bacteria that can respire anaerobically can survive.
      • Energy is always released during anaerobic respiration, but the products of the reactions are different depending on the type of cell it happens in
      • Anaerobic respiration can produce lactic acid
        • In animal cells and some bacteria anaerobic respiration causes lactic acid
      • Anaerobic respiration can also produce ethanol and carbon dioxide
        • In plant cells and some microorganisms (like yeast) anaerobic respiration produces ethanol and carbon dioxide
        • Fermentation is where microorganisms break down sugars into other products as they respire anaerobically. humans use fermentation to make lots of things like booze, biogas, and bread

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