B1 Cells and microscopy

• What is an organism?


  A living thing
• What is a unicellular organism?

  An organism made up of one cell
• What is a multicellular organism?

  An organism made up of many cells
• What is a eukaryotic cell?


  A cell with a nucleus. Animal and plant cells are examples of eukaryotic cell
• What’s in a typical animal cell?

  Nucleus, mitochondria, cell membrane, cytoplasm and ribosomes
• What is in a plant cell but not an animal cell?

  Chloroplasts, vacuole, cell wall
• What does a nucleus do?


  Controls the activities of the cell and contains DNA
• What is the function of cytoplasm?


  Site of most chemical reactions
• What is the function of the cell membrane?


  Controls the movements of substances in and out of the cell
• What is the function of mitochondria?


  Where energy is released in respiration
• What is the function of ribosomes ?


  Makes proteins and is the site of protein synthesis
• What is the function of the cell wall?


  Strengthens the cell and is made of cellulose
• What is the function of chloroplasts?


  They absorb light energy to make food in a process called photosynthesis and are made of chlorophyll
• What is the function of the vacuole?


  Stores sugars for the cell in the form of cell sap
• What is a prokaryotic cell ?


  The DNA is not within the nucleus and bacteria cells are examples of prokaryotic cells
• Where is the DNA contained in bacteria cells?


  Plasmids and a free loop of DNA
• How do you convert from metres to millimetres ?


  X 1000
• How to convert millimetres or micrometers ?


  X 1000
• How to convert micrometers to nanometres ?


  X 1000
• What is a specialised cell?


  A cell that has adaptations that enable the cell to perform specific jobs
• What is the job of the sperm cell?


  To fertilise the egg cell
• What are the adaptations of the sperm cell?

  Streamlined shape - Allows it to move quickly

  Many mitochondria - Release energy for swimming by respiration

  Tail - to swim
• What is the job of the nerve cell?


  Pass on information as electrical impulses
• What are the adaptations of the nerve cells?


  Branched structure - allows communication with lots of cells

  Long shape - allows info to pass over a long distance
• What is the job of the muscle cells?


  Enable movement
• What are the adaptations of the muscle cell?

  Mitochondria -Release energy for movement by respiration

  Contractile filaments - Allows contraction and relaxation
• What is the job of the root hair cell?


  Absorbs water and minerals from the soil
• What are the adaptations of root hair cells?


  Thin walls - To increase absorption

  Hair like structure - Gives a larger surface structure
• What is the job of the xylem?


  Transports water and minerals
• What are the adaptations of the xylem?


  Long tube formed from dead cells - Transports water over a long distance

  Wall strengthened with lignin - Strong and waterproof

  Water flows in one direction
• What is the job of phloem?


  Transports sugar
• What are the adaptations of phloem ?

  Long tube made of living cells - Transports sugar over long distances

  Pores in cell wall - allows sugars to move between cells easily

  Sugars transported in both directions
• As an organism develops cells differentiate and their structures change to to carry out different functions and become specialised
• What are stem cells?

  Cells that are unspecialised and can differentiate into any type of cell or reproduce to form new stem cells
• What is a light microscope ?

  Low magnification and resolution

  Cheap and don’t produce 3D images
• What is an electron microscope?


  High magnification and resolution

  Expensive and can produce 3D images
• How has the electron microscope improved understanding of cells?


  Allowed very small structures inside the cell to be seen and allowed microbes to be studied
• Image size = Actual size / Magnification
• How do you use a scale bar to calculate magnification?


  Measure the scale bar using correct units

  Use image size / actual size
• What does only a bacteria cell contain?

  Plasmids and single loops of DNA