define promoter; tRna; exons.

Dear student,
 

tRNA= tRNA is transfer RNA. It is RNA molecule responsible for the translation process in protein synthesis. In two dimensions tRNA has three loops one of which is the anti codon . Opposite to the anticodon is the amino acid attachment site. In three dimensions it is a L shaped structure bent in the middle.

Exons=Exons are sequences present only on eukaryotic DNA that code for functional proteins or functional RNA. They alternate with stretches of regulatory DNA called introns which do not code for any proteins. In essence an exon will always give rise to mRNA (and in some cases rRNA) when an RNA polymerase passes over it.

Promoter= Sequence of DNA to which proteins bind and it will initiate transcription of a single RNA from the DNA downstream of it.

Regards.