4.10.4.10. G-QADRUPLEX
 

• Structure of a DNA quadruplex formed by telomere repeats. The conformation of the DNA backbone diverges significantly from the typical helical structure.
• These guanine-rich sequences may stabilize chromosome ends by forming very unusual structures of stacked sets of four-base units, rather than the usual base pairs found in other DNA molecules. Here, four guanine bases form a flat plate and these flat four-base units then stack on top of each other, to form a stable G-quadruplex structure.
• Telomeres and telomerase have recently received great attention because of their potential links to cancer, HIV and other diseases. A unique G-rich DNA sequence in the telomeres was found to protect the chromosomes from recombination, end to end fusion, and degradation through forming G-quadruplexes with highly polymorphic structures in the presence of alkali metal cations. This unusual structure and extensive cellular functions make G-quadruplex a very attractive target for drug design, which made it important for determination of G-quadruplex.

Figure 4.10: Structure of G-quadruplex.

4.10.4.11. DNA IS A STORE OF GETIC INFORMATIONS

DNA contains all of the information necessary to make a complete organism, like the human shown here. DNA is a very useful molecule for storing this information because it is extremely stable - you can’t break it apart easily. It’s also easy to replicate. That is, machinery in the cell can make many copies of it with few mistakes.

4.11. THE COMPARATIVE STRUCTURE OF DNA AND RNA