Structure Of A Dna Sequencer

A DNA sequencer is composed of an electrophoresis system, which includes a sieving matrix (e.g., polyacryl-amide gel), buffer, a high-voltage power supply, and a detection system. When a high voltage (1000 V to 10 kV) is applied to the gel, an electric field forces negatively charged fragments of DNA molecules to move through the mesh created by polymer molecules constituting the gel. The difference in the friction for the DNA fragments of different sizes leads to their spatial separation. Groups of molecules of the same size propagate through the gel as a set of confined bands with the width defined by such factors as diffusion, injection conditions, sample volume, field, and temperature gradients, etc.

Manual and automated instruments, in their principle of operation, mainly differ by the method of detection. In manual sequencers the electrophoretic run is stopped as soon as the first base of interest (typically a primer) reaches the end of the gel. Then, information about DNA sequence is obtained by determining the relative position of the bands in the gel. In automated sequencers, the detection system records variations of the output intensity over time at a fixed location in the gel. The difference in the migration times of various DNA chain lengths results in a set of electrophoretic peaks.

Automated DNA sequencers can be divided into three major categories based on the method used for sieving matrix support: slab gel, capillary, and micro-array sequencers.

Getting Started With Dumbbells

Getting Started With Dumbbells

The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.

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