plz need explanation (nbme question0 - kath2329

[ArchivalUser]

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
© 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

[ArchivalUser]

wouldn't that be C ? not sure

[ArchivalUser]

oups!!!
meant D , I over read . Presence of introns in H.influenzae DNA

[ArchivalUser]

Hi, I think it's A.
Methylation inhibits the activity of Restriction Endonucleases.

[ArchivalUser]

Rt.
*A*
Restriction endonucleases attack of palindrome inverted repeats in story is immune by methylation/methylase.

[ArchivalUser]

yesss i worked it out to be A too!

@kath: since they're sampling DNA theres not question about introns vs extrons. its all introns that becomes mRNA that becomes DNA.

[ArchivalUser]

thank u so much!