Final answer:
Expressed sequence tags (ESTs) are partial cDNA sequences used in genomic analyses to identify active gene fragments and contribute to faster and more reliable physical mapping of genomes.
Step-by-step explanation:
Expressed sequence tags (ESTs) are crucial in genomic analyses, and they are specifically partial cDNA sequences that represent gene fragments expressed in certain tissues or at certain development stages. These ESTs are generated by taking the mRNA from cells, converting it into cDNA using reverse transcriptase, and then sequencing a portion of it. ESTs are useful because they provide a snapshot of which genes are active in a particular cell at a given time. Moreover, ESTs help in identifying gene transcripts, and in creating physical maps of genomes by locating these ESTs within the genome. This has proven to be a faster alternative compared to traditional genetic mapping as it is not affected by increased or decreased recombination frequency, thereby overcoming one of the limitations faced by traditional genetic mapping approaches.
An expressed sequence tag (EST) is a short sequence-tagged site (STS) that is identified with complementary DNA (cDNA) libraries in genomic analyses. ESTs are partial cDNA sequences that represent the parts of genes that are actively transcribed and expressed in a specific tissue or cell type. They are used to study gene expression, identify new genes, and provide valuable information about the functional elements of the genome.