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Given the two 10-nucleotide sequences, line them up and compare the differences between them. Calculate the percent difference by taking the number of differences between the DNA bases divided by the total number of nucleotides. In this case there are three differences in the 10 nucleotide sequence. Thus there is a 30% difference.
The first method for determining DNA sequences involved a location-specific primer extension strategy established by Ray Wu at Cornell University in 1970. [33] DNA polymerase catalysis and specific nucleotide labeling, both of which figure prominently in current sequencing schemes, were used to sequence the cohesive ends of lambda phage DNA.
This nucleotide contains the five-carbon sugar deoxyribose (at center), a nucleobase called adenine (upper right), and one phosphate group (left). The deoxyribose sugar joined only to the nitrogenous base forms a Deoxyribonucleoside called deoxyadenosine, whereas the whole structure along with the phosphate group is a nucleotide, a constituent of DNA with the name deoxyadenosine monophosphate.
DNA sequencing is the process of determining the nucleotide order of a given DNA fragment. So far, most DNA sequencing has been performed using the chain termination method developed by Frederick Sanger. This technique uses sequence-specific termination of a DNA synthesis reaction using modified nucleotide substrates.
DDBJ (Japan), GenBank (USA) and European Nucleotide Archive (Europe) are repositories for nucleotide sequence data from all organisms. All three accept nucleotide sequence submissions, and then exchange new and updated data on a daily basis to achieve optimal synchronisation between them.
These creative approaches to visualizing DNA sequences have generally relied on the use of spatially distributed symbols and/or visually distinct shapes to encode lengthy nucleic acid sequences. Alternative notations for nucleotide sequences have been attempted, however general uptake has been low. Several of these approaches are summarized below.
Sequences can be complementary to another sequence in that the base on each position is complementary as well as in the reverse order. An example of a complementary sequence to AGCT is TCGA. DNA is double-stranded containing both a sense strand and an antisense strand. Therefore, the complementary sequence will be to the sense strand. [4]
The Reference Sequence (RefSeq) database [1] is an open access, annotated and curated collection of publicly available nucleotide sequences (DNA, RNA) and their protein products. RefSeq was introduced in 2000.