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What is Semi-Log Graph paper…. And WHY do I need to know?

What is Semi-Log Graph paper…. And WHY do I need to know?. DNA can be cut, using RESTRICTION ENZYMES… into segments of differing lengths.

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What is Semi-Log Graph paper…. And WHY do I need to know?

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  1. What is Semi-Log Graph paper…. And WHY do I need to know?

  2. DNA can be cut, using RESTRICTION ENZYMES… into segments of differing lengths.

  3. After DNA is separated on an agarose gel by electrophoresis, the migration of fragments of known size can be compared to that of fragments of unknown size.

  4. Suppose we have digested DNA from two viruses ~ both with Hind III, • And electrophoresed the DNA from both on an agarose gel

  5. Electrophoresing the DNA on an agarose gel ~~ causes the migration of the fragments.

  6. After running the gel ~ you measure the distance the DNA migrated.

  7. Table 1. Restriction enzyme analysis of λ and UPCFV DNAλ Virus U.P. Cabin Fever Virus (UPCFV) DNA Hind III digest DNA Hind III digestSize (kb) Distance (mm) Size Distance (mm) migrated migrated23.1 3 ? 5 9.42 14 ? 12 6.56 18.5 ? 15 4.36 23.5 ? 27 2.32 32. 2.03 34 0.56 50

  8. In order to determine the sizes of the U.P. Cabin Fever Virus DNA, you will make a standard curve for the known Lamda DNA • YUK! This does not show a linear relationship between the fragment size and distance migrated… down towards the right side of the graph, it would be difficult to determine size… Length migrated Size of fragment

  9. A logarithmic graph, basically takes an EXPONENTIAL graph and changes it to a LINEAR one … but using funky graph paper & by using the log function. (log function is the inverse of an exponential function) Length migrated Size of fragment

  10. When a curve is not straight.. It can be made straight with logarithms. Log of fragment length migration

  11. Scientists use logarithmic graph paper to manage large amounts of data easily

  12. And when you are talking kilo base pairs…. And DNA…. You are discussing a LARGE amount of data

  13. See the funky graph paper? The axis with the logarithmic info runs in cycles… The cycles differ by a factor of 10 btw, this is an example of 6 cycle graph paper

  14. See the funky graph paper? One of the virtues of semi-logarithmic plots is their ability to show a very wide range of values.

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