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Kaplan Qbank USMLE



Author4 Posts
  #1

1. DNA from Escherichia coli and Haemophilus influenzae is digested with the restriction endonuclease EcoRI and the fragments separated by agarose gel electrophoresis. An examination of the gel shows that the DNA from H. influenzae was cleaved into numerous smaller fragments while that from E. coli was not. Which of the following best explains this difference?

A. Methylation of E. coli DNA
B. Methylation of H. influenzae DNA
C. Presence of introns in E. coli DNA
D. Presence of introns in H. influenzae DNA
E. Presence of transposons in E. coli DNA
F. Presence of transposons in H. influenzae DNA

shocked

  #2

A methylation of E.coli is a defence mechanism to protect them from foreign invasion.

  #3

d?

  #4

this is a simple one. methylation of e coli is going to prevent the degradation of its components the basics of bacterial protective mechanism.







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