F211 - Module 1 Cells

F211 - Module 1 Cells

1. Cell Structure

   • Microscopy
     • MAGNIFICATION = how large the image is compared to reality
     • RESOLUTION = the ability to distinguish between two objects or pieces of information in the image
     • Light Microscope
       • Magnification - max. x1500
       • shines light through specimen, and is focused through the objective lens, to produce an image
     • actual size=image size/magnification
     • Electron Microscope
       • Transmission Electron Microscope TEM
         • use magnets to hit specimen with beam of electrons
         • 2D Greyscale micrograph is produced
           • denser areas are darker bc electron dense = contrast
         • Magnification - max. x500 000
       • Scanning Electron Microscope SEM
         • An electron beam is directed at the sample at an angle
         • produce a 3D micrograph
           • the bounces are recorded to give surface of sample
         • Magnification - max. x100 000
       • Advantages
         • resolution is much higher than light microscope
           • can be used to produce detailed images
         • SEM produces 3D image
       • Disadvantages
         • Very expensive
         • preparation of specimen requires a lot of skills, high level of training
         • required to be done in a vacuum bc electron beams are deflected by molecules in the air
           • Very expensive
     • staining allows the specimen to be seen. the colour stain may bind to specific cell structures or chemicals on or in the specimen
   • Organelles
     • mitochondria
       • 2 membranes, inner membrane heavily folded = cristae, centre = matrix
       • Role: produces most ATP during respiration, almost all active processes use energy from mitchondria
     • Nucleus
   • Prokaryotes and Eukaryotes