biology aqa flashcards topic 1 microscopy

• Cell


  The smallest living part, the building block of life
• Eukaryotic cell


  Cells which contain their DNA in a nucleus
• Nucleus


  Controls all activities of the cell
• Cytoplasm


  Where most chemical reactions take place
• Cell membrane


  Controls what substances go in and out of the cell
• Mitochondria


  Where aerobic respiration takes place, releases energy for the cell to use
• Ribosomes


  Site of protein synthesis (where proteins are made)
• Cell wall


  Strengthens the cell, provide support
• Cellulose


  Substance that makes up plants' cell walls
• Chloroplasts


  Contain chlorophyll, absorb light to do photosynthesis
• Permanent vacuole


  Stores sap, helps to keep plant cells rigid to provide support
• Differences between animal and plant cells


  • Plant cells have chloroplasts
  • Plant cells have permanent vacuole
  • Plant cells have cellulose cell wall
  • Animal cells do not have these
• Prokaryotes


  Do not have a nucleus
• Eukaryotes


  Have a nucleus
• Bacteria are prokaryotic organisms
• Prokaryotes have a cell wall
• Slime capsule


  Extra layer on top of prokaryotic cell walls
• Prokaryotic DNA


  Exists in the cytoplasm
• Differences between prokaryotic and eukaryotic DNA

  • Prokaryotic DNA is circular
  • Eukaryotic DNA is linear
• Plasmid


  Extra small DNA rings found in some prokaryotes
• Flagella


  Allow the cell to swim and move around
• Differences between animal cells and bacteria


  • Animal cells have no cell wall and no plasmid, have linear DNA
  • Bacteria have cell wall and plasmid, have circular DNA
• Plant cells and bacterial cells


  • Both have cell walls (but different material)
• Magnification, image size and actual size equation


  Image Size = Actual Size x Magnification
• 5mm converted to µm is 5000 µm (microns)
• Calculating total magnification of a microscope


  Eyepiece lens x Objective lens magnifying power
• The objective lens we should start using when using a microscope is the lowest power (x4)
• Specimen preparation for light microscope


  Must be thin and usually stained
• How electron microscopy has increased understanding of organelles


  • Electron microscopes have much greater magnification and resolution, allowing organelles to be seen
• Image using an electron microscope


  Black and grey (not transparent) sometimes in 3D
• We must not use the coarse focus knob during high power magnification as it moves the stage by too much, may break the slide on the objective lens