Please enable JavaScript.

Coggle requires JavaScript to display documents.

Biology (B1 (Cell Structure (Parts of a cell (Nucleus - contains genetic…

- - - - Plant cell
      - Animal cell
      - Eukaryotic cells have a cell membrane, cytoplasm and genetic material enclosed in a nucleus
    - - Bacteria cell
      - Prokaryotic cells are smaller than eukaryotic cells. The genetic material is not enclosed in a nucleus. The DNA is in a single loop and there may be one ore more rings of DNA called plasmids
    - - Nucleus - contains genetic material, which controls the activities of the cell. It is located in animal and plant cells
      - Cytoplasm - most chemical processes take place here. Controlled by enzymes. This is located in all of the cells.
      - Cell membrane - Controls the movement of substances into and out of the cell. It is located in all of the cells
      - Mitochondria - Most energy is released here by respiration. It is located in animal and plant cells.
      - Ribosomes - Protein synthesis takes place here. It is located in animal and plant cells.
      - Cell wall - Strengthens the cell. For plant cells it is made from cellulose. It is located in plant and bacteria cells.
      - Chloroplasts - contains chlorophyll, absorbs light energy for photosynthesis. It is located in plant cells.
      - Permanent Vacuole - Filled with cell sap to keep the cell hard. It is located in plant cells
      - Bacterial DNA - loop of DNA NOT found in a nucleus.It is located in bacteria cells.
      - Plasmid - Small ring of DNA. It is located in bacteria cells.
      - Flagella - Something on the end of a cell to help with movement. It is located in a bacteria cell.
    - - The structure of different cells helps them carry out a particular job within the organism. These are called specialised cells
      - Sperm Cell
        
        Function = To fertilise an egg. It is streamlined so it can swim to the egg. It has acrosome in the head containing enzymes to digest the egg cell membrane. It has a large number of mitochondria in the middle section to release energy for movement.
      - Nerve Cell
        
        Function = To carry electrical signals. It is long to carry signals long distances. It has branched connections to connect to other nerve cells and form a network around the body. insulating sheath to enhance transmission of electrical signals
      - Muscle cell
        
        Contain a large amount of mitochondria to release energy during respiration for movement. they are long so that there is enough space to contract
      - Root Hair Cell
        
        Function = to absorb minerals and water from the soil. It has hair like projections to increase the surface area. They have no chloroplasts as they do not need them in soil.
      - Xylem Cell
        
        Function = To carry minerals and water in plants. It forms hollow xylem tubes made of dead tissue. Long cells with walls toughened by lignin. Water and minerals flow from the roots to the leaves only in one direction in a process called TRANSPIRATION
      - Phloem Cell
        
        Function = To carry glucose around the plant. Form phloem tubes that are made from living tissue. Cells have end plates with holes in them. Glucose in solution moves from the leaves to growth and storage tissues in a process called TRANSLOCATION
    - - Cell differentiation occurs as organisms develop, the cell changes and becomes specialised. As the cell differentiates, it forms different sub-cellular structures (e.g. the tail on a sperm)
    - - Light microscope
        
        Radiation used = light rays
        
        Max magnification = 1500 times
        
        Resolution = 200nm
        
        Size = small and portable
        
        Cost = 100 pounds
        
        A light microscope has a lower magnification and resolution than an electron microscope but they can see structures like nuclei and mitochondria.
      - Electron microscope
        
        Radiation used = electron beams
        
        Max magnification = 2,000,000 times
        
        Resolution = 0.2nm
        
        Size = Very large and not portable
        
        Cost = 100,000 to 1 million pounds
        
        Electron microscopes have a higher magnification and resolution than light microscopes so they can see more sub-cellular structures in a cell
      - Resolution = the shortest distance between two objects that can be seen clearly
      - How to calculate magnification
        
        Magnification (M) = size of image (I) divided by real size of object (A)
        
        Magnification = the number of times bigger the image looks compared to the object
        
        Image = What is viewed through the microscope lenses
        
        Object = The ACTUAL specimen under the microscope
      - MICROSCOPY PRACTICAL
        
        Method (onion cells)
        
        Place a thin section of specimen onto the slide
        
        Stain the specimen or place a drop of water in the middle of the slide
        
        Gently lower cover slide onto specimen without leaving any air bubbles
        
        Switch on your light source and place your slide on the stage
        
        Use the lowest objective wheel and turn the focusing wheel to move the lens closer to the slide
        
        Adjust the focusing wheel until you see a clear image
        
        Increase the magnification by changing the objective lens and re-focus
        
        Draw a diagram of the onion cell
        
        Diagram