基于EST全基因組定位的基因結構注釋研究.pdf

1、華中科技大學碩士學位論文基于EST全基因組定位的基因結構注釋研究姓名：井輝申請學位級別：碩士專業(yè)：生物信息技術指導教師：周艷紅20070208II Abstract Identification of protein coding genes is a crucial issue of genome research. As genomes of more and more species have been sequenced, th

2、e issue is becoming particularly important. Traditional biological experiments could hardly tackle the whole problem with the explosion of genomic sequences, which makes the high throughput methods of bioinformatics inva

3、luable. An EST (expressed sequence tag) is a partial sequence of a clone picked at random for cDNA library. In theory, an EST contains no introns and represents part of a gene. The amount of ESTs is very large and is gro

4、wing fast. It is an extremely precious resource. Prediction and annotation of protein coding genes using genomically aligned ESTs is a crucial issue. However, this is not a trifle due to the poor quality of EST sequences

5、 and the complexity of genome. Characteristics of EST sequences have been studied at first. Several factors concerning the quality of EST sequences have been investigated, including foreign sequences, genomic DNA sequenc

6、es, chimeric sequences, pre-mRNA sequences, random-primed sequences, internal-primed sequences and so on. Components of the genome have also been studied, such as repeats, pseudo genes, multi-copy genes, overlapping gene

7、s, nested genes and alternative splicing. Based on these analyses, several measures have been brought up according to different cases involved in the alignments between EST sequences and the genome. The annotation proced

8、ures include trimming foreign sequences, locating ESTs on the genome, verifying and testing the alignments, clustering between each other and predicting the final gene structure. At the prediction step, directed acyclic