Question

I would like you to investigate a commercially available DNA sequencing device. In 2-3 paragraphs describe the fundamental biological/chemical mechanisms which are harnessed to produce the sequence. Also describe some of the advantages and disadvantages you see in the device.

Answer 1

DNA sequencing device:

DNA sequencing device is a scientific instrument used to automate the DNA sequencing process.It is a method used to determine the precise order of the four nucleotide bases; Adenine, Guanine, Cytosine and Thymine, that make up a strand of DNA.

DNA sequencing played a vital role in mapping out the human genome and it is an essential tool for many basic and applied research applications today.

DNA sequencing provides the means to know how nucleotide bases are arranged in a piece of DNA. This can be done either mechanically or chemically. Several methods have been developed for this process. These have four key steps.

(1) In the first instance DNA is removed from the cell.

(2) The second phase involves breaking up the DNA and inserting its pieces into vectors , cells that indefinitely self replicate, for cloning.

(3) In the third phase the DNA clones are placed with a short stretch of DNA that promotes replication into a thermal cycler, a machine which automatically raises and lowers the temperature to catalyse replication.

(4) The final stage consists of electrophoresis, whereby the DNA segments are placed in a gel and subjected to an electrical current which moves them.

ADVANTAGES :

1; High sensitivity, gold standard complete sequence.

2: High sensitivity provides percentage of mutated versus wild type DNA.

DISADVANTAGES:

1: Very time consuming, cannot detect deletions, translocations or copy number changes.

2: Often difficult to resolve differences in melt curves. Difficult to standardize. Multiplex capability is limited.