12.07.2015 Views

PRINCIPLES OF TOXICOLOGY - Biology East Borneo

PRINCIPLES OF TOXICOLOGY - Biology East Borneo

PRINCIPLES OF TOXICOLOGY - Biology East Borneo

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

246 MUTAGENESIS AND GENETIC <strong>TOXICOLOGY</strong>One possibility, infidelity or inexact copying of a DNA strand during normal cellular replication, mayresult from inaccurate initiation of replication, failure of the transcription enzymes to accurately “read”the DNA, or interruption of the transcription process by agents that interpose (intercalate) themselveswithin the DNA molecule or between the DNA and an enzyme.Point mutations, as the second possibility, may be subdivided into basepair changes and frameshiftmutations (Figure 12.4). The former result from transition or transversion of DNA base pairs so thatFigure 12.4 Schematic representation of point mutations (frameshift and basepair changes).

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!