Cell Biology

• Cell membrane


  Surrounds the cell and controls the passage of substances into and out of the cell.

  
• Cell wall


  Found outside the cell membrane in plant and bacterial cells, provides support for the cell.

  
• Chloroplast


  Found in plant cells. Contain chlorophyll that absorbs light for photosynthesis.

  
• Cytoplasm


  Where most of the chemical reactions take place in a cell.

  
• Domain


  Name given to the groups suggested by Woese. There are three domains: Archae, Bacteria and Eukaryota.

  
• Eukaryote


  Type of cell that contains a nucleus

  
• Mitochondria


  Where aerobic respiration takes place.

  
• Nucleus


  Contains DNA and controls cell activities.

  
• Plasmid


  Small rings of DNA found in bacterial cells.

  
• Prokaryote


  Cells without a nucleus.

  
• Ribosomes


  Where protein synthesis occurs.

  
• Vacuole


  Found in plant cells. Contain a fluid called cell sap.

  
• Cell


  The basic unit of living things.
• Differentiation


  When cells become specialised to do a particular job.

  
• Organ


  A group of tissues working together to perform a specific function.

  
• Organ system


  Groups of organs that work together e.g. digestive system.

  
• Specialised


  Cells that have a particular job/function.

  
• Tissue


  A group of cells with a similar structure and function.
• Translocation


  The movement of sugars in plants.
• Transpiration


  The movement of water through the plant and leaves.
• Epidermis (plant)


  A single layer of cells that forms the outer layer.
• Palisade


  Tissue found in the upper layer of the leaf, packed with chloroplasts for photosynthesis.

  
• Spongy mesophyll


  Tissue found in the lower layer of the leaf, with spaces between the cells to allow gases to diffuse.

  
• Xylem


  Water travels through xylem tissue from the roots to the leaves.
• Phloem


  Sugars are transported through the phloem cells.
• Guard cells


  Cells which surround the stomata and control its opening and closing.

  
• Stomata


  Tiny pores in the epidermis of the leaf.

  
• Electron microscope


  A microscope that uses electron beams in place of light to give a higher magnification.
• Light microscope


  An instrument that uses visible light and lenses to magnify a specimen.

  
• Magnification


  How many times larger something appears.

  
• Micrograph


  Another word for a microscope image.

  
• Resolving power


  The ability to distinguish between two points.

  
• Magnification of image


  Magnification = size of image/size of real object
• Total magnification


  Magnification = magnification of eyepiece x magnification of objective lens

  
• Adult stem cell


  Stem cells found in some adult tissues. They are partly specialised and can become a range of different type of cell, but not all.

  
• Asexual reproduction


  Reproduction involving only one parent, producing genetically identical offspring.

  
• Benign


  Type of tumour that is slow growing, not cancerous and usually easy to remove.
• Cancer


  A condition resulting from changes in cells that leads to their uncontrolled growth, division and spread.

  
• Carcinogen


  Chemicals and other agents that cause cancer.

  
• Chromosome


  Long strands of DNA found in cells. Human body cells have 46 chromosomes.