In: Biology
Describe the events that must all come together for transcription of a Class II gene. Include in your answer the stages of preinitiation/initiation and elongation. include diagrams also
STEPS OF TRANSCRIPTION
Transcription is the process by which the information in a strand of DNA is copied into a new molecule of messenger RNA (mRNA). The major steps are :
Pre initiation : Transcription of class II genes requires the formation of a preinitiation complex. The preinitiation complex is a complex of approximately 100 proteins that is necessary for the transcription of protein-coding genes in eukaryotes.
The preinitiation complex positions RNA polymerase II at gene transcription start sites, denatures the DNA, and positions the DNA in the RNA polymerase II active site for transcription.
Initiation. Initiation is the beginning of transcription which occurs when the enzyme RNA polymerase binds to a region of a gene called the promoter. This signals the DNA to unwind so the enzyme can ''read'' the bases in one of the DNA strands.
Elongation. Elongation is the addition of nucleotides to the growing mRNA strand as the RNA polymerase moves down the DNA template strand.
Termination. Transcription ends in a process called termination once the polymerase transcribes a sequence of DNA known as a terminator.