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Title Mystery of DNA replication, The
Subject DNA--Synthesis
Description The 43rd Annual Frederick William Reynolds Lecture.
Creator Lark, Karl G.
Publisher University of Utah Press
Date 1980-03-05
Date Digital 2008-05-29
Type Text
Format application/pdf
Digitization Specifications Original scanned on Epson Expression 10000XL flatbed scanner and saved as 400 ppi uncompressed tiff. Display images generated in PhotoshopCS and uploaded into CONTENTdm Aquisition Station.
Resource Identifier,83
Source QP624 .L37
Language eng
Relation Digital reproduction of "The Mystery of DNA replication," J. Willard Marriott Library Special Collections
Rights Digital Image Copyright University of Utah
Metadata Cataloger Seungkeol Choe; Ken Rockwell
ARK ark:/87278/s65q4t2n
Setname uu_fwrl
Date Created 2008-07-29
Date Modified 2008-08-04
ID 319398
Reference URL

Page Metadata

Title Page16
Description 16 KARL G. LARK tion could begin. Moreover, other cell components including new fats and RNA had to be made in order to initiate replication. At the same time, geneticists were discovering new genes which regulated DNA replication. Soon, several were shown to control initiation of replication and several were shown to determine different proteins involved in the replication process itself. (Today, more than twenty such components exist and the number still grows.) It was clear that, in the living cell, many components were involved in replication. While simple in principle, replication was not simple in practice. Initially, these experiments did little to influence the biochemical approach to replication. Instead, a paradox was growing out of the biochemistry itself. The enzyme, polymerase I, would add subunits only to existing DNA (that is, it could extend a chain while copying a template, but it could not initiate polymerization). Moreover, it could not add units in either direction, only in one. This created a problem because of the opposite polarity of the DNA strands. As the helix unwound in one direction, one template required polymerization in the right-handed sense, whereas to keep up, the other demanded the mirror image or left-handed sense. Polymerization did in fact occur on both sides of the helix as it unwound in the living cell. In a beautiful demonstration of this, John Cairns devised a technique whereby replicating molecules could be induced to make a self-portrait or autoradiograph. He showed that the bacterial chromosome was a circle, as had been predicted by genetic evidence, and that replication occurred in one sequential step, copying both sides of the double helix and proceeding on both sides in the same direction â€" despite the opposite polarity of the two templates. The paradox of polarity created a great deal of concern. Moreover, as the enzyme reaction was examined in ever greater detail, more problems arose. If the DNA strands were separated to begin with, the enzyme could faithfully copy the already-unwound templates, but the enzyme alone did not seem to be capable of unwinding DNA. Given a double-stranded molecule like a Watson-Crick helix, the enzyme synthesized strange structures that looked like
Format application/pdf
Identifier 022-RNLT-LarKK_Page16.jpg
Source Original Manuscript: The mystery of DNA replication by Karl G. Lark.
Setname uu_fwrl
Date Created 2008-07-29
Date Modified 2008-07-29
ID 319377
Reference URL