A segment of an eucaryotic gene that is not represented in the mature mRNA, is known as:
Introns are the RNA sequences in the primary transcript that are not found in the mRNA. Exons RNA sequences in the primary transcript that are found in the mRNA. A TATA box is a DNA sequence that indicates the point at which a genetic sequence can be read and decoded. Transcription: Transcription is the process by which DNA is copied (transcribed) to mRNA, which carries the information needed for protein synthesis. Transcription takes place in two broad steps. First, pre-messenger RNA is formed, with the involvement of RNA polymerase enzymes. Second formation of Messenger RNA. Transcription unit: is a linear sequence of DNA that extends from a transcription sta site to a transcription stop site. The transcription unit--that poion of a gene that is copied by RNA polymerase--consists of coding regions of DNA (exons) interrupted by intervening sequences of noncoding DNA (introns). After transcription, during RNA processing, introns are removed and the exons are ligated together to form the mature mRNA that appears in the cytoplasm. 1) Transcription Steps: There are three main steps to the process of DNA transcription. Initiation: RNA Polymerase Binds to DNA. DNA is transcribed by an enzyme called RNA polymerase. Specific nucleotide sequences tell RNA polymerase where to begin and where to end. RNA polymerase attaches to the DNA at a specific area called the promoter region. Elongation: Ceain proteins called transcription factors unwind the DNA strand and allow RNA polymerase to transcribe only a single strand of DNA into a single stranded RNA polymer called messenger RNA (mRNA). The strand that serves as the template is called the antisense strand. The strand that is not transcribed is called the sense strand. Termination: RNA polymerase moves along the DNA until it reaches a terminator sequence. At that point, RNA polymerase releases the mRNA polymer and detaches from the DNA. 2) Pre mRNA processing: RNA splicing: pre-mRNAs typically include introns.Exons:are the continuous coding regions. Introns: are the noncoding intervening sequences. They may serve to separate functional domains (exons) of coding information in a form that permits genetic rearrangement by recombination to occur more rapidly than if all coding regions for a given genetic function were contiguous. Introns are removed by RNA processing in which the intron is looped out and cut away from the exons by snRNPs, and the exons are spliced together to produce the translatable mRNA. Ref: Harper's illustrated biochemistry, 26th Edition Page 319
Exon
Intron
Plasmid
TATA box