Cellular components & microscopy

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  • Created by: HeHeHe24
  • Created on: 05-12-19 20:56
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  • Cellular components
    • Magnification
      • how many times larger the image is compared to the actual size
      • = Image size / actual size
    • resolution
      • degree of clarity to which you can distinguish between 2 different objects
      • Limitations
        • diffraction of light through the sample
    • microscopy
      • light microscope
        • advantages
          • observe living things
          • cheap
          • easy to set up & portable
          • no harsh chemicals
        • disadvantage
          • low resolution
          • low magnification(x2000
        • sample preparation
          • dry mount - cut thinly and place with a cover slip
          • wet mount - suspend in liquid, place cover slip over at an angle
          • squash slide - prepare a wet mount and press down with lens slip
          • smear slide - edge of slide used to smear at an angle
        • differential stain
          • used to distinguish between different organelles otherwise hard to identify
          • stain cell cytoplasm
            • congo red
            • nigrosin
            • negatively repel cytosol
          • stain cell component
            • crystal violet
            • methylene blue
            • attracts negatively charged cytosol
      • Electron microscope
        • disadvantage
          • non living materials used
          • expensive
          • non portable & hard to use
          • harsh chemicals needed- cause artefacts
        • Scanning EM
          • advantages
            • high magnification (x500000)
            • high resolution
            • see detailed 3D images
        • Transmission EM
          • advantages
            • high resolution
            • high magnification (x20000000)
            • see detail
    • prokaryotic cells
      • single celled
        • no membrane bound organelles
      • nucleus
        • Naked DNA
        • not present
        • circular DNA not wound around histone proteins into chromosome
          • Plasmids
      • ribosomes
        • smaller 70s
      • cell wall
        • peptidoglycan
      • replication
        • binary fission
          • DNA replicated
          • split by cytokinesis
    • Eukaryotic cells
      • multicellular
      • Plasma membrane
        • selectively permeable
        • allows small non polar molecules to pass
      • nucleus
        • contains genetic information
          • DNA in linear chromosomes
          • histone proteins
        • nuclear envelope
          • double membrane to protect
        • nucleolus
          • produces ribosomes
        • nuclear pore
          • allows mRNA to leave
      • Mitochondria
        • cellular respiration to produce ATP
      • Vesicles
        • membrane bound sacs
        • transport materials in and out
        • stores material
      • lysosomes
        • release hydrolytic enzymes
      • Cytoskeleton
        • microfilament
          • contractile actin fibres for cell movement
        • microtubules
          • globular tublin proteins
          • polymerise to tubes
          • determine shape
        • intermediate fibres
          • mechanical strength
          • maintains cell integrity
        • centrioles
          • 2 microfilaments at 90o
          • spindle fibre formation
      • flagella
        • movement
      • cilia
        • fluid movement
      • ribosomes
        • synthesise proteins
        • SER
          • no ribosomes
          • lipid and carbohydrate synthesis and storage
        • RER
          • ribosomes
          • synthesis and transport protiens
        • golgi apparatus
          • processes and packages proteins into vesicles
            • transport or storage
    • plant components
      • Cell wall
        • Cellulose
        • Yeast
          • Chitin
        • freely permeable
        • rigid to give shape
        • defence mechanism against pathogens
      • Chloroplasts
        • photosynthesis
      • permanent vacuole
        • tonoplast membrane has cell sap
        • Untitled

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