CELLS+MICROSCOPY

• eukaryotic cells


  • plants and animals
  • more complex
• prokaryotic cells


  • bacteria
  • smaller and simpler
• what does an animal cell contain?


  • nucleus
  • cytoplasm
  • mitochondria
  • ribosomes
  • cell membrane
• what does a plant cell contain?


  • cell wall
  • chloroplasts
  • nucleus
  • cytoplasm
  • mitochondria
  • ribosomes
  • cell membrane
• nucleus


  contains DNA (genetic material) in the form of chromosomes that controls the cells activities
• cytoplasm


  gel-like substance where most of the chemical reactions happen
• mitochondria


  the site of cellular respiration and contains the enzymes needed for the reactions involved.
• ribosomes


  where proteins are made in the cell
• cell membrane


  • holds the cell together
  • controls what goes in and out by providing a selective barrier
  • contains receptor molecules used for cell communication
• cell wall


  • made of cellulose
  • gives support for the cell
• chloroplasts


  • where photosynthesis occurs
  • they contain a green substance called chlorophyll
• 3 structures in prokaryotic cells


  • chromosomal DNA
  • plasmids
  • cell membrane
• chromosomal DNA


  • controls the cells activities and replication
  • floats free in the cytoplasm (not in a nucleus)
• plasmids


  • small loops of extra DNA that aren't part of the chromosome
  • plasmids contain genes for things like drug resistance and can be passed between bacteria
• cell membrane


  • controls what goes in and out of the cell
  • prokaryotic cell is also supported by a cell wall
• what do microscopes use to magnify images


  they use lenses
• what does increasing the resolution of an image mean


  • increase the detail you can see
• what is resolution


  how well a microscope distinguishes between two points that are close together
• when were light microscopes invented


  1590s
• what do light microscopes let us see


  nuclei and chloroplasts
• when were electron microscopes invented

  1930s
• what do electron microscopes let us see


  much smaller things in more detail, such as the internal structure of mitochondria
• what did electron microscopes allow us to do


  • have a much greater understanding of sub cellular structures
  • let us see things as tiny as plasmids or viruses
• TEM

  transmission electron microscope
• positives of TEM

  • higher magnification and resolution than light microscopes
• negatives of TEM

  • not portable
  • expensive
  • complicated process to prepare specimens for use
  • can't look at live specimens