Oligonucleotide Synthesis Is Now Routine

The automated chemical synthesis of moderately long oligonucleotides (about 100 nucleotides) of precise sequence is now a routine laboratory procedure. Each synthetic cycle takes but a few minutes, so an entire molecule can be made by synthesizing relatively short segments that can then be ligated to one another. Oligonucleotides are now indispensable for DNA se-

Reaction containing radiolabel:

ddGTP ddATP ddTTP ddCTP

Sequence of original strand:

b la Sl

Reaction containing radiolabel:

ddGTP ddATP ddTTP ddCTP

b la Sl

Bases terminated

Bases terminated

AGTCTTGGAGCT

Figure 40-6. Sequencing of DNA by the method devised by Sanger. The ladder-like arrays represent from bottom to top all of the successively longer fragments of the original DNA strand. Knowing which specific dideoxynu-cleotide reaction was conducted to produce each mixture of fragments, one can determine the sequence of nucleotides from the labeled end (asterisk) toward the unlabeled end by reading up the gel. Automated sequencing involves the reading of chemically modified deoxynucleotides. The base-pairing rules of Watson and Crick (A-T, G-C) dictate the sequence of the other (complementary) strand. (Asterisks signify radiolabeling.)

quencing, library screening, protein-DNA binding, DNA mobility shift assays, the polymerase chain reaction (see below), site-directed mutagenesis, and numerous other applications.

Diabetes 2

Diabetes 2

Diabetes is a disease that affects the way your body uses food. Normally, your body converts sugars, starches and other foods into a form of sugar called glucose. Your body uses glucose for fuel. The cells receive the glucose through the bloodstream. They then use insulin a hormone made by the pancreas to absorb the glucose, convert it into energy, and either use it or store it for later use. Learn more...

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