- Eukaryotic gene example
Many
genomes have been sequenced and their gene sequences are stored in general DNA sequence databases (e.g.GenBank ) and in species specific databases (e.g. TheArabidopsis Information Resource (TAIR).The figures are views of the sequence of one (AMY1) of the approximately 25,000 genes from "
Arabidopsis thaliana " theThale Cress plant.This gene encodes an alphaamylase enzyme.These images are views of the gene, cDNA, and coding sequence (
CDS ) used by researchers to study it further. Such research might involve seed germination or plant flavour.cDNA
The image below shows a screenshot of the [http://www.arabidopsis.org/servlets/TairObject?type=gene&id=1000641818 AMY1]
cDNA . This was obtained from [http://www.arabidopsis.org/servlets/sv?action=seq&start=12851579&length=10000&band=0&option2=0 TAIR]Note that TAIR provide three views of the 'Nucleotide Sequence', 'full length CDS', 'full length cDNA' (Fig. 1), 'full length genomic' (Fig. 2] . In each of them the DNA alphabet is used, although strictly the CDS should be shown as RNA (AUG etc).
A typical eukaryotic gene is transcribed into an
pre-mRNA that is then processed into a maturemRNA by removal ofintron s and 5' and 3' processing.Gene and mRNA
The mature
mRNA is comprised of a5' UTR (red)CDS (uppercase yellow) and3' UTR (red again) (Fig. 2). All three of these regions areexon ic (not just the protein coding sequence (CDS)).Intron s are shown in purple (lowercase) and are not present in the mature mRNA.For convenience neither the 5' Cap nor 3' tail are shown in the cDNA (fig 1) although the mRNA will have them. The gene sequence is also shown in a form where the codons can be read (ATG...), rather than as the template DNA strand which is actually copied into mRNA.
This gene structure view is typical of a eukaryotic gene. Similar views of genes can be obtained for
human ,fruitfly , oryeast genes.External links
* [http://www.arabidopsis.org/ The Arabidopsis Information Resource (TAIR)]
* [http://arabidopsis.org/seqViewer/help/sv_nuc.jsp#seqann Help for these types of displays at TAIR]
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