b1

• eukaryotic cells


  contain genetic material in a nucleus (plant and animal cells)
• nucleus


  controls the cell and contains genetic material
• cell membrane


  controls which substances enter and leave the cell and contains receptor molecules
• cytoplasm

  where chemical reactions take place
• mitochondria

  where aerobic respiration occurs and contains the enzymes needed
• cell wall (plant)


  supports the cell
• chloroplast (plant)


  contains chlorophyll and is where photosynthesis occurs
• vacuole (plant)


  stores cell sap and makes cell rigid
• flagella (bacteria)


  allows cell to move through liquids
• pili (bacteria)


  allows cells to attach to structures and transfer genetic material
• slime capsule (bacteria)


  protects bacterium from drying out and poisonous substances
• plasmid (bacteria)


  piece of DNA used to store extra genes
• resolution


  ability to see details
• features of a light microscope

  eye piece lens, objective lens, slide, stage, corse focus, fine focus, light
• light microscope advantages


  - look at dead or living cells

  - cheap

  - easy to use
• light microscope disadvantages


  - lower magnification

  - lower resolution
• how a light microscope works

  - using a light source

  - objective lens focuses and magnifies specimens

  - eye piece further magnifies specimen
• light microscope resolution


  2x10^-2m
• total magnification =


  eye piece lens magnification x objective lens magnification
• magnification =


  size of image/size of real object
• how electron microscope works

  uses electrons instead of light to produce an image (black and white)

  
• advantages of EM

  - higher magnification

  - higher resolution

  - allows scientists to see structures inside cells
• disadvantages of EM


  - expensive

  - complex to use

  - speciemens have to be dead
• gene


  short section of DNA that codes for protein
• chromosomes


  long molecules of DNA

  
• structure of DNA


  - a polymer made up of monomers called nucleotides

  - twos trends form a double helix

  - have 4 bases; A and T, G and C

  
• what are enzymes


  - proteins

  - biological catalysts
• what do enzymes do

  - speed up chemical reaction without being used up

  - break down large molecules or join smaller molecules together
• lock and key hypothesis


  only a substrate with a specific shape can fit into the active site

  
• effect of temperature on enzymes

  - as the temp increase the rate of reaction increases

  - the higher the temp, the more collisions as molecules have more kinetic energy

  - reaction is fastest at the optimum temp

  [ - above the optimum temp, enzymes denature and changes (irreversible change)

  - substrate cannot bind so rate decreases ]
• effect of pH on enzymes

  - enzymes denature if pH is too high
• effect of enzyme concentration

  - as enzyme concentration increases, rate of reaction increases

  - reaction stops once enzymes have run out of substrates
• effect of substrate concentration

  - as substrate concentration increases, rate of reaction increases

  - rate of reaction then reaches a maximum and the active sites are full
• investigating enzyme activity


  to measure enzyme action, you measure:

  - how long it takes for an enzyme to break sown a substrate

  or - how quickly a product is formed
• metabolic rate


  speed at which chemical reactions in your cell transfer energy from its chemical sores in food
• carbohydrates


  polymers made of sugar (carbohydrase) eg. starch
• proteins


  polymers made of amino acid (protease)
• lipids (fats and oils)


  each molecule contains 1 glycerol and 3 fatty acids
• aerobic respiration


  - releases ATP (energy)

  - occurs in all organisms

  - takes place in the mitochondria

  - is exothermic (gives out heat)

  - required for movement, maintaining body temp and bulging large molecules
• aerobic respiration formula


  glucose + oxygen ---> carbon dioxide + water c6h12o6 + 6o2 ---> 6co2 + 6h2o