Question

Discuss the general structure of the eukaryotic promoter including in your answer how a limited number of transcription factors allow the regulation of gene expression.

Answer 1

Answer:

• Promoter region on DNA is a sequences that define where transcription of a gene by RNA polymerase begins. Many eukaryotic genes have a conserved promoter sequence called the TATA box, located 25 to 35 base pairs upstream of the transcription start site.
• The enzyme RNA polymerase search for promotor for its attachment on gene.

PROMOTER is made up of following ELEMENTS:

1):Core promoter:

• the minimal portion of the promoter required to properly initiate transcription
• Transcription Start Site (TSS)
• Approximately -34
• A binding site for RNA polymerase
• General transcription factor binding sites

2): Proximal promoter:

• The proximal sequence upstream of the gene that tends to contain primary regulatory elements
• Approximately -250
• Specific transcription factor binding sites
• Eukaryotic promoters are extremely diverse and are difficult to characterize.
• They typically lie upstream of the gene and can have regulatory elements several kilobases away from the transcriptional start site.
• In eukaryotes, the transcriptional complex can cause the DNA to bend back on itself, which allows for placement of regulatory sequences far from the actual site of transcription.
• Many eukaryotic promoters, contain a TATA box (sequence TATAAA), which in turn binds a TATA binding protein which assists in the formation of the RNA polymerase transcriptional complex.
• The TATA box typically lies very close to the transcriptional start site (often within 50 bases).

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