AAMC FL1 B/B #57

mshah
Posts: 18
Joined: Mon Aug 28, 2017 4:21 pm

AAMC FL1 B/B #57

Postby mshah » Mon Dec 11, 2017 11:59 am

The experiment makes sense and I understand how to get the answer. But how do you know it is double-stranded DNA and not single-stranded DNA in the bacterium?
NS_Tutor_Andrew
Site Admin
Posts: 520
Joined: Mon May 23, 2016 1:47 pm

Re: AAMC FL1 B/B #57

Postby NS_Tutor_Andrew » Wed Dec 13, 2017 2:00 pm

Hi mshah,

In general, all non-viral life will always have dsDNA as its genome -- viral genomes can be dsDNA, ssDNA, +/- sense ssRNA, and even dsRNA. The experiment they describe is known as the Meselson-Stahl experiment, and it's worth knowing, b/c it's an elegant, historically relevant, and MCAT-testable experiment that confirmed semiconservative replication.

Hope this is helpful!
Andrew D.
Content Manager, Next Step Test Prep.

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