Examination Papers

Date:
1959
Reference:
PP/CRI/E/1/7/3/3
Catalogue details

Licence: In copyright

Credit: Examination Papers. Source: Wellcome Collection.

    6/10
    Chemistry 192b toe Hour Examination of March 11, 1959, continued. 3. Draw a diagram (very roughly to scale) to show the two kinds of base-pairs believed to occur in DNA between the four common bases. Mention some other bases which have been found in DMA. State briefly the source of the DNA in each case. Can you suggest any reason why uracil is not normally found in DNA? 4. The crystals of a certain protein from a pig and another from a horse have identical unit cells, th® same space group P 2^2.^2 (4 asymmetric units in the unit cell) and very similar X-ray dif fraction patterns. How similar might these two proteins be? Prom th© X-ray photo the volume of the unit cell of one of these protein crystals is found to be 400,000 Their density is 1.17 and their content of protein 50£ by weight. The molecular weight of the protein in solution is found (by sedimentation-dif fusion) to be 70,000. What would you deduce from this about the molecule in solution? Explain your reasoning. » 1 cm. Take Avogadro's number as 6 X 10 25 ]