Transcription is the DNA-directed synthesis of RNA: a closer look A. Describe the general
model of transcription. Include in your answer the steps of transcription elements of each step.
B. Compare and contrast transcription between prokaryotes and eukaryotes. C. What makes
RNA polymerase start transcribing in a gene at the right place on the DNA of a prokaryotic cell?
D. What makes RNA polymerase start transcribing in a gene at the right place on the DNA of a
eukaryotic cell?
Solution
17.2). a).
Transcription is the synthesis of RNA (ribonucleic acid) under the direction of DNA in the
nucleus. The process of transcription starts with RNA polymerase, this enzyme binds to the
sigma factor (in prokaryotes) and in this form; it can recognize the promoter sites in the DNA
and is transcribed into RNA.
The three steps in eukaryotic transcription include the following.
Several of the transcription factors bind to the promoter region to recruit the appropriate RNA
polymerase. The complex of RNA polymerase and transcription factors bind to the promoter
region to form a pre-initiation complex (PIC).
A group of transcription factors assemble at the promoter region of DNA, and bind to TATA box
to change its shape. This event exposes the binding sites of other transcription factors. After
several of these events, RNA polymerase binds.
The binding of RNA polymerase (moves in 3\' to 5\' direction) to the promoter site starts the
process of transcription. There are three different classes of RNA polymerases that bind to
different promoter sites and transcribe different parts of genome. Of these, RNA polymerase II
causes the transcription of mRNA. The mRNA contains uracil in place of thymine and it moves
into the cytoplasm through the nuclear pore channels.The terminator present at another end of
the genome signals the completion of transcription, thus terminating the programme..
Transcription is the DNA-directed synthesis of RNA a closer look A..pdf
1. Transcription is the DNA-directed synthesis of RNA: a closer look A. Describe the general
model of transcription. Include in your answer the steps of transcription elements of each step.
B. Compare and contrast transcription between prokaryotes and eukaryotes. C. What makes
RNA polymerase start transcribing in a gene at the right place on the DNA of a prokaryotic cell?
D. What makes RNA polymerase start transcribing in a gene at the right place on the DNA of a
eukaryotic cell?
Solution
17.2). a).
Transcription is the synthesis of RNA (ribonucleic acid) under the direction of DNA in the
nucleus. The process of transcription starts with RNA polymerase, this enzyme binds to the
sigma factor (in prokaryotes) and in this form; it can recognize the promoter sites in the DNA
and is transcribed into RNA.
The three steps in eukaryotic transcription include the following.
Several of the transcription factors bind to the promoter region to recruit the appropriate RNA
polymerase. The complex of RNA polymerase and transcription factors bind to the promoter
region to form a pre-initiation complex (PIC).
A group of transcription factors assemble at the promoter region of DNA, and bind to TATA box
to change its shape. This event exposes the binding sites of other transcription factors. After
several of these events, RNA polymerase binds.
The binding of RNA polymerase (moves in 3' to 5' direction) to the promoter site starts the
process of transcription. There are three different classes of RNA polymerases that bind to
different promoter sites and transcribe different parts of genome. Of these, RNA polymerase II
causes the transcription of mRNA. The mRNA contains uracil in place of thymine and it moves
into the cytoplasm through the nuclear pore channels.The terminator present at another end of
the genome signals the completion of transcription, thus terminating the programme.
