What is an EST database?
The expressed sequence tag (EST) databases contain an increasingly large part of the transcriptome of many species. For this reason, these databases are probably the most abundant source of new coding sequences available today.
What does the term ESTs refer to?
Expressed Sequence Tags (ESTs) are DNA sequences (genes) that are expressed as mRNA for protein synthesis. These are used in Human Genome Project. So, the correct answer is ‘Genes expressed as RNA’.
What are ESTs used for?
Expressed sequence tags (ESTs) are relatively short DNA sequences (usually 200–300 nucleotides) generally generated from the 3′ ends of cDNA clones from which PCR primers can be derived and used to detect the presence of the specific coding sequence in genomic DNA.
What are STS and EST?
EST (expressed sequence tag): A unique stretch of DNA within a coding region of a gene that is useful for identifying full-length genes and serves as a landmark for mapping. An STS is a short segment of DNA which occurs but once in the genome and whose location and base sequence are known.
What is an EST and why would you expect to find such results for a particular gene?
EST sequences contain at least partial sequences of most mRNAs present in the various tissues used for library construction. Therefore, they have been used intensively as a source of information for the discovery of new genes whose function can be tentatively deduced from their sequence, and experimentally verified.
What is EST mapping?
EST (cDNA) mapping refers to the mapping of EST (cDNA) sequence file to the reference genome base sequence by using its homology to identify the genomic position from which EST is derived and registering the EST (cDNA) feature at that position.
How do ESTs work?
ESTs are generated by sequencing cDNA, which itself is synthesized from the mRNA molecules in a cell. The mRNA in a cell are copies of the genes that are being expressed.
How is EST used?
An EST results from one-shot sequencing of a cloned cDNA. The cDNAs used for EST generation are typically individual clones from a cDNA library. The resulting sequence is a relatively low-quality fragment whose length is limited by current technology to approximately 500 to 800 nucleotides.
What is BAC and YAC?
The term YAC stands for yeast artificial chromosome and the term BAC stands for bacterial artificial chromosomes. These are the two vectors which are basic tools to insert the gene of interest in the host cell. The key difference between these two vectors is that of the insert size of the gene of interest.
What is a human EST?
The Expressed Sequence Tag (EST) division of Gen-Bank, dbEST, is a large repository of the data being generated by human genome sequencing centers. ESTs are short, single pass cDNA sequences generated from randomly selected library clones.
What are EST give advantages also?
ESTs contain enough information to permit the design of precise probes for DNA microarrays that then can be used to determine gene expression profiles. Some authors use the term “EST” to describe genes for which little or no further information exists besides the tag.
How are EST sequences represented in a database?
They may be represented in databases as either cDNA/mRNA sequence or as the reverse complement of the mRNA, the template strand . One can map ESTs to specific chromosome locations using physical mapping techniques, such as radiation hybrid mapping, Happy mapping, or FISH.
How are ESTs generated in a DNA database?
Est database. 2. ESTs are small pieces of DNA sequence (usually 100 to 800 nucleotides long) generated by sequencing randomly selected cDNA clones from a library Expressed Sequence Tags (ESTs) are short , single-pass sequence reads from mRNA (cDNA).
Where can I find history of ESTs in GenBank?
A brief account of the history of human ESTs in GenBank is available (Trends Biochem. Sci. 20:295-6;1995). Also, consult the special “Genome Directory” issue of Nature (vol. 377, issue 6547S, 28 September 1995).
Why are EST libraries not annotated in dbEST?
A first challenge is that tissue provenance of EST libraries is described in plain English in dbEST. This makes it difficult to write programs that can unambiguously determine that two EST libraries were sequenced from the same tissue. Similarly, disease conditions for the tissue are not annotated in a computationally friendly manner.