Cell Biology

• What is a eukaryotic cell?

  A cell that contains a nucleus.
• What is a prokaryotic cell?


  A cell that does not contain a nucleus, and is smaller than a eukaryotic cell.
• What is the function of the nucleus?

  The nucleus contains the genetic material (DNA) and also controls the activities of the cell.
• What is the function of the cytoplasm?

  The cytoplasm is a gel-like substance where most of the chemical reactions happen inside the cell.
• What is the function of the cell mebrane?

  The cell mebrane holds the cell together and controls which substances enter and exit the cell.
• What is the function of the mitochondria?

  The mitochondria is where most of the aerobic resporation reactions take place in the cell.
• What is the function of the ribosomes?

  The ribosomes are where proteinsynthesis occurs in the cell.
• What is the function of the cell wall?

  The cell wall strenghtens and supports the cell.
• What is the funtion of the permanent vacuole?

  The permanent vacuole contains cell sap.
• What is the function of chloroplasts?

  Chloroplasts are were photosynthesis takes place in the cell.
• What are the three sub-cellular structures that are in plant cells but not animal cells?

  The permanent vacuole, chloroplasts and the cell wall.
• What do bacterial cells have instead of a nucleus?

  A single circular loop of DNA and/or plasmids.
• Name two reasons why electron microscopes are better than light microscopes?

  Higher resolution and higher magnification.
• How do you calculate magnification?

  $Magnification =$$image size/realsize$
• How do you prepare a slide in microscopy?

  1. Add a drop of water to middle of slide.
  2. Place the specimen into the water on the slide.
  3. Add a drop of iodine solution to stain the cells.
  4. Place a cover slip on top.
• How do you view a slide in microscopy?

  1. Clip the prepared slide to the stage.
  2. Select the lowest magnifiction objective lens.
  3. Use the coarse adjusment knob to move the stage to below the objective lens.
  4. Look down the eyepiece and use the coarse adjusment knob to move the stage down until the image is slightly in focus.
  5. Adjust the focus with the fine adjustment knob until the image is clear.
• What is differentiation?


  The process by which a cell changes to become specialised for its job.
• How are sperm cells specialised for reproduction?

  Long tail and a streamlined head to help swim to the egg.

  Lots of mitochondria to provide energy.

  Enzymes in the head to digest through the egg cell membrane.
• How are nerve cells specialised for rapid signalling?

  They are long to cover more distance and have branched connections at their ends to connect to other nerve cells to form a network through the body.
• How are muscle cells specialised for contraction?

  They are long so they have space to contract and contain lots of mitochondria to provide the energy needed for contraction.
• How are root hair cells specialised for absorbing water and minerals?

  They are long and stick into the soil which gives the plant a big surface area for absorbing water and mineral ions.
• How are phloem and xylem cells specialised for transporting substances?

  Xylem cells are hollow and phloem cells have very few sub-cellular structures so substances can move through them.
• How many pairs of chromosomes are in a human cell?

  23 pairs.
• What do multicellular organisms use mitosis for?

  To grow or replace damaged cells.
• What is mitosis?


  The process of cell division where two identical daughter cells are formed.
• Describe how the process of mitosis works?

  1. The cell grows and increases the amount of sub-cellular structures it has.
  2. It then duplicates its DNA which is copied and forms x-shaped chromosomes.
  3. The chromosomes line up at the centre of the cell and cell fibres pull them apart.
  4. Membranes form around each of the sets of chromosomes, and these become the nuclei of the cells therefore the nucleus has divided.
  5. Lastly, the cytoplasm and cell membrane divide to form two identical daughter cells.
• What type of cells replicate by binary fission?

  Prokaryotic cells.
• Describe the process of binary fission?

  1. The circular loop of DNA and plasmids replicate.
  2. The cell grows and the circular DNA strands move to opposite poles (ends) of the cell.
  3. The cytoplasm begins to divide and new cell walls begin to form.
  4. The cytoplasm divides and two daughter cells are produced.
• What conditions allow bacteria to divide quickly?

  Warm environment and lots of nutrients.
• What is binary fission?

  Asexual reproduction in a prokaryotic cell.