B2 - Topic 1 - 1.4 - 1.7

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  • Created by: topcat543
  • Created on: 07-04-14 18:24
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  • B2 - Topic 1 - 1.4
    • 1.4 Be able to describe how plant and animal cells can be studied in greater detail with a light microscope.
      • Microscopes enable you to objects (like microorganisms) which you cannot see with the naked eye
      • Microscopes using the visible part of the electromagnetic spectrum (visible light) were invented in the late 16th century
      • With these light microscopes you can see individual cells and smaller details such as nuclei and mitochondria in all cells, and chloroplasts in plant cells.
    • 1.5 Be able to demonstrate an understanding of how changes in microscope technology have enabled us to see cells with more clarity
      • In the 20th century, with advances in atomic physics, the electron microscope was invented which works off beams of electrons instead of visible light.
      • This has enabled the magnification produced by a microscope to be considerable increased
        • to the point where you can see even smaller structures such as the internal details of mitochondria, chloroplasts and plasmids
      • magnification = length of image / length of object
    • 1.6 Know that a gene is a section of a molecule of DNA and that it codes for a specific protein.
      • The genetic code ('blueprint') to make a particular protein is in the form of a sequence of bases attached to the sugar-phosphate backbone of a DNA molecule.
    • 1.7 Be able to describe a DNA molecule as
      • a) two strands coiled together to form a double helix
      • b) strands linked by a series of complementary base pairs joined together by weak hydrogen bonds
        • There are four bases in DNA holding the structure together and the same bases are always paired together.
          • adenine (A)
            • thymine (T)
          • cytosine (C)


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