Final answer:
Eukaryotic gene transcription is regulated by transcription factors that bind to the promoter region, facilitating the formation of a preinitiation complex that recruits RNA polymerase II. Enhancers, silencers, and DNA methylation also play roles in regulating transcription efficiency.
Step-by-step explanation:
The regulation of gene transcription in eukaryotic cells is a complex process involving the orchestrated action of multiple transcription factors and the chemical modification of DNA. To enable RNA polymerase II to initiate transcription, a preinitiation complex is formed at the gene's promoter region. This process is facilitated by the binding of transcription factors to specific DNA sequences within the promoter, such as the TATA box, GC box, and CAT box in higher eukaryotes, or the TATA box and upstream activator sequence (UAS) in yeast.
Once the transcription factors have bound to these sequences, they assist in recruiting RNA polymerase II to the site. Basal transcription factors are required to form the preinitiation complex, along with other transcription factors bound to upstream enhancers and silencers that regulate transcription efficiency. Additionally, nucleotide methylation sites may enhance the binding of regulatory proteins to enhancers, helping to stabilize DNA conformation for effective transcription initiation.
In summary, transcription initiation and efficient gene expression are regulated by a diverse set of mechanisms, including transcription factor binding, DNA methylation, and complex formation with RNA polymerase and other accompanying proteins.