Genomes can have known sequences {DNA sequencing}. H. influenzae has 1.8 million bases and 800 genes. E. coli has 4.5 million bases and 2000 genes. Saccharomyces yeast has 12 million bases and 6000 genes. P. falciparum has 30 million bases and 6500 genes. Caenorhabditis elegans roundworm nematode has 100 million bases and 10000 genes. Arabidopsis thaliana weed has 120 million bases and 20000 genes. Drosophila melanogaster fruitfly has 165 million bases. Fugu rubripes is zebrafish. Mus musculus mouse has 3000 million bases. Humans have 3500 million bases and 30000 genes.
methods
Sequencing {plus-minus method} can elongate DNA sequences using DNA polymerase.
Sequencing {Maxam-Gilbert sequencing method} can chemically degrade labeled, short DNA chains at G, C, A and G, and T and C to make fragments and then electrophorese all four, separately or together, to separate by size.
Sequencing {Sanger sequencing method} can elongate DNA chains and randomly terminate them with nucleotides that cannot bind to next ribose, using A, G, T, and C 2',3'-dideoxynucleoside triphosphates, and then electrophoreses all four, separately or together, to separate by size.
Mixing differently labeled clones {multiplex DNA sequencing} allows easier processing. Labels identify clones.
DNA-fragment ends can have fluorescent dyes, which respond to laser light. Dye terminator attaches to nucleotide 3' ends. Dye primer attaches to 5' ends. Longer fragments have higher signals. Fragments separate by electrophoresis in gels {horizontal ultrathin gel electrophoresis} (HUGE) or capillary tubes {capillary gel electrophoresis}. Because charges are equal, fragments leave gel or tube by size.
Scanning tunneling electron microscopes can sequence DNA strands by wand distance needed to maintain constant voltage. They can sequence 40000-base DNA fragments one base at a time. Exonuclease removes end nucleotide. Shining laser light and recording with photomultiplier reads nucleotide type.
Gas or liquid mixtures can separate using gas chromatography, liquid chromatography, supercritical fluid chromatography, or capillary electrophoresis.
Biological Sciences>Genetics>Recombinant DNA>DNA Sequencing
4-Genetics-Recombinant DNA-DNA Sequencing
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Date Modified: 2022.0224