Explain (in one or two lines) the function of the followings:
Promoter is a region of DNA that helps in initiating the process of transcription. It serves as the binding site for RNA polymerase.
tRNA or transfer RNA is a small RNA that reads the genetic code present on mRNA. It carries specific amino acid to mRNA on ribosome during translation of proteins.
Exons are coding sequences of DNA in eukaryotes that transcribe for proteins.