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Chain Termination Method (Sanger et al 1977) In this method sequence of single stranded DNA molecule determined. This is done by enzymatic synthesis of complementary polynucleotide chain. These chains terminate at specific nucleotide positions. Principle Single stranded DNA differing in length by single nucleotide can be separated by polyacrylamine gel electrophoresis . So we can get lengths from 10 to 1500 nucleotide into series of bands. Steps Starting material is identical s ingle s tranded DNA molecule. Then short oligonucleotide is annealed to each single stranded molecule at same position . These gonucleotide acts as primer . Strand synthesis requires DNA polymerase , dNTPs (Deoxyribonuleotide triphosphate) as substrate. The DNA synthesis doesn't continue for long because along with dNTPs small amount of ddNTPs ( Dideoxyribonucleotide triphosphate – It lacks 3'-hydroxyl group need to form connection with next nucleotide) is added . The polymerase can't discri

Sample Preparation Hundreds and thousands of copies of single cell type is made from which protein can be extracted. Get Cell: Cell of single type is grown, obtained from biopsy or body fluids Culture Cell: Cells are then placed in growth medium in petridish. Cells feed and multiply. Now base of the petridish is covered with thousands of cells . Make More Copies: Cells are again divided in more petridishes to get more copies of cells. Millions of copies are produced. Then the cells are scraped from petridish base and put it in test tube Add Detergent: Detergent added ruptures outer membrane of cell membrane. Now the test tube contains proteins along with cell debris . Spin: The solution is know centrifuged to separate proteins form cell debris like cell membrane, cytoskeleton. After centrifugation the test tube contains cell debris at bottom and protein above . Separation A single cell has millions of protein type. Hence there separation is necessary. 2D Electrophoresis:

A virus has helped to create a new type of tiny battery , made with a simple stamping technique that could power miniature devices . Electronic devices used for controlled drug delivery , or to power tiny lab-on-a-chip applications , need to get their power from somewhere. But as conventional batteries are made smaller and smaller, they contain less and less of the materials that actually store charge, causing a decline in efficiency . Using nanoscale components can boost a battery's capacity to store charge. Now, scientists at the Massachusetts Institute of Technology, Cambridge, have designed a quick method to build a microbattery that relies on a genetically-engineered virus called M13. The scientists first made a template from polydimethylsiloxane (PDMS), a commonly used silicon-based organic polymer. After coating it with alternating layers of positive and negative electrolytes , they added the virus . The virus had been designed to have negatively charged amino aci

Do you know? The first human chromosome to be sequenced is chromosome no 22. The sequencing completed in December 1999 The genetic code of it comprised of 33.5 million bases About Chromosome 22 Chromosome 22 is the second smallest of the human autosomes. The short arm (22p) contains a series of tandem repeat structures including the array of genes that encode the structural RNAs of the ribosomes , and is highly similar to the short arms of chromosomes 13, 14, 15 and 21. The long arm (22q) is the portion of human chromosome 22 that contains the protein coding genes and this is the region that has now been sequenced. The completed sequence consisted of 12 contiguous segments covering 33.4 million bps separated by 11 gaps of known size. One of these gaps has subsequenctly been closed by the Oklahoma group. The sequence is estimated to cover 97% of 22q, and is complete to the limits of currently available reagents and methodologies. The largest contiguous contig is >23 million bps