Topic 1 - cell biology

• What are prokaryotic cells


  Cells without a nucleus (e.g bacteria) they are smaller and are a single celled organism without mitochondria
• What are eukaryotic cells


  Cells with a nucleus (e.g. Animal and plant cells) they are complex and have mitochondria, cell membrane and cytoplasm
• What are the 5 sub cellular structures in an animal cell.


  Nucleus, mitochondria, cytoplasm, cell membrane, ribosomes
• What is the function of the nucleus

  Contains genetic material that controls the activities of the cell
• What is the function of the cytoplasm 


  Gel like substance where most of the chemical reactions happen. Contains enzymes that control these reactions
• Function of cell membrane


  Holds the cell together and controls what goes in and out
• Function of Mitochondria 


  Where aerobic respiration takes place. Respiration transfers energy that the cell needs to work
• Function of ribosomes 


  Where proteins are made for protein synthesis
• What are the three sub cellular structures that plants cells have that animal cells don’t 


  Cell wall, vacuole, chloroplasts
• Function of cell wall


  Rigid and made of cellulose. It supports the cell and strengthens it
• Function of vacuole


  Contains cell sap which is a weak solution of sugar and salts. It helps give the cell its shape
• Chloroplasts 


  Where photosynthesis occurs. Contains chlorophyll, a green substance which absorbs light.
• Are bacteria cells prokaryotic or eukaryotic?

  prokaryotic
• What do bacteria have 


  Cell membrane, cell wall, cytoplasm
• What do bacteria have instead of a nucleus 


  A single circular strand of DNA that floats freely in the cytoplasm. They contain one or more small rings of DNA called plasmids.
• What do light microscopes do

  Use light and lenses to form an image of a specimen and magnify it.
• What do light microscopes allow Us to see 


  Let’s us see individual cells and large subcellular structures (e.g nuclei)
• Are light or electron microscopes cheaper

  Light
• what do electron microscopes do

  use electrons to form an image. higher magnification and resolution
• What do electron microscopes allow us to see 


  Let’s us see smaller things in detail (e.g. internal structure of mitochondria and chloroplasts and small things like ribosomes and plasmids
• What does resolution mean


  The ability to distinguish between two points
• How do you Calculate magnification

  Magnification= image size/real size
• describe how to prepare a microscope slide

  Add a drop of water to the middle of a slide. Cut up an onion and separate it out into layers. Use tweezers to peel some epidermal tissue from the bottom of one of the layers. Using the tweezers, place the epidermal tissue into the water on the slide. Add a drop of iodine solution. Iodine id a stain. Stains are used to highlight objects in a cell by adding colour. Place a cover slip on top. Tilt/lower it so it covers the specimen. Try not to get air bubbles as they obstruct your view of the specimen
• Describe how to use a light microscope to look at a slide

  1. Clip the prepared slide onto the stage
  2. use the coarse adjustment knob to move the stage up to just below the objective lens.
  3. Look down the eyepiece. Use the coarse adjustment knob to move the stage down until the image is in focus
  4. adjust the focus with the fine adjustment knob until you get a clear image of what’s on the slide
  5. swap to a higher powered objective lens and refocus if you need to see the slide with greater magnifixation.
• Describe how to draw your observations neat

  Use a pencil with a sharp point, no colouring or shading, include title and write magnification, label important features
• What is differentiation 


  Process by which a cell changes to become specialised for its job
• What happens as cells change to carry out a specific function?

  They develop different sub cellular structures and turn into different types of cells
• When does most differentiation occur

  As an organism develops
• When is the ability to differentiate lost in animal and plant cells 


  In animal cells the ability to differentiate is lost at an early stage, after they become specialised. Plant cells don’t ever lose this ability
• Do Animal or plant cells lose the ability to differentiate

  Plant cells
• What are the cells that differentiate in mature animals used for

  For repairing and replacing cells such as skin or blood cells
• Explain what a nucleus contains 


  Contains your genetic material in the form of chromosome. Each chromosome carries a large number of genes. Differebt genes control the development of different characteristics
• How many copies of each chromosome do body cells have

  Two
• What is a chromosome 


  Thread like structure carrying genetic information
• What is an allele

  a version of a particular gene
• What are chromatids

  Duplicating chromosone produced during mitosis
• What is cytokinesis

  Dividing of the cell in the last stage of mitosis
• What is a nerve cell specialised for

  Rapid signalling
• function of nerve cell


  To carry electrical signals from one party of the body to another. They are long to cover more distance. Have branched connections at their ends to connect to other nerve cells and form a network throughout the body
• What is a muscle cell specialised for

  Contraction