cell biology

• Prokaryotic cell


  A small simple cell, e.g. a bacterium
• Eukaryotic cell


  A complex cell, e.g. a plant or animal cell
• in which sub-cellular structures do most of the reactions of aerobic respiration take place?

  The reactions take place mostly in the mitochondria
• Bacterial cell vs Plant cell

  • Similarities: both have a cell membrane, cell wall, cytoplasm

  Differences: plant cells have chloroplasts and mitochondria, bacteria do not; plant cells have a true nucleus, bacteria have a single circular strand of DNA; bacteria may contain plasmids
• Cell membrane


  Holds the cell together and controls what enters and leaves
• Nucleus


  Contains the genetic material that controls the activities of the cell
• Cytoplasm


  Gel-like substance where chemical reactions happen, contains enzymes that control these reactions
• Fine adjustment knob on a light microscope

  Used to focus the lens until a clear image of what's on the slide appears
• Electron microscopes vs light microscopes

  Electron microscopes have a higher resolution and higher magnification than light microscopes
• Electron microscopy


  • Lets biologists study cells in much finer detail than light microscopes
  • Enables seeing and understanding more sub-cellular structures like ribosomes, plasmids, internal structures of mitochondria and chloroplasts
• Iodine


  A stain used to highlight objects in onion cells by adding colour, making them easier to see
• Calculating image size from magnification and real size


  1. Magnification = image size / real size

  2. Image size = magnification x real size
• Cell Differentiation and Specialisation


  The process by which a cell changes to become specialised for its job
• Sperm cell function


  To transport the male DNA to the female DNA in eggs for reproduction
• Xylem cell function


  To transport water and minerals up plants
• Xylem cells


  • They are long and joined end to end, forming hollow tubes. This means that substances can flow through them.
• Nerve cell function


  To carry electrical impulses (signals) from one part of the body to another
• Nerve cells


  • They are long and have branched connections at their ends to connect to other nerve cells and form a network throughout the body. This allows for rapid signalling.