is TTGACA. The σ-factor binds to the -35 promoter region. At this point, the holoenzyme is referred to as the closed complex because the DNA is still double stranded (connected by hydrogen bonds). Once the σ-factor binds, the remaining subunits of the polymerase attach to the site. The high concentration of adenine-thymine bonds at the -10 region facilitates the unwinding of the DNA. At this point, the holoenzyme is called the open complex. This open complex is also called the transcription bubble. Only one strand of DNA, called the template strand (also called the noncoding strand or nonsense/antisense strand), gets transcribed. Transcription begins and short "abortive" nucleotide sequences approximately 10 base pairs long are produced. These short sequences are nonfunctional pieces of RNA that are produced and then released. Generally, this nucleotide sequence consists of about twelve base pairs and aids in contributing to the stability of RNA polymerase so it is able to continue along the strand of DNA. The σ-factor is needed to initiate transcription but is not needed to continue transcribing the DNA. The σ-factor dissociates from the core enzyme and elongation proceeds. This signals the end of the initiation phase and the holoenzyme is now in core polymerase form. The promoter region is a prime regulator of transcription. Promoter regions regulate transcription of all genes within bacteria. As a result of their involvement, the sequence of base pairs within the promoter region is significant; the more similar the promoter region is to the consensus sequence, the tighter RNA polymerase will be able to bind. This binding contributes to the stability of elongation stage of transcription and overall results in more efficient functioning. Additionally, RNA polymerase and σ-factors are in limited supply within any given bacterial cell. Consequently, σ-factor binding to the promoter is affected by these limitations. All promoter regions contain sequences that are considered non-consensus and this helps to distribute σ-factors across the entirety of the genome. Elongation During elongation, RNA polymerase slides down the double stranded DNA, unwinding it and transcribing (copying) its nucleotide sequence into newly synthesized RNA. The movement of the RNA-DNA complex is essential for the catalytic mechanism of RNA polymerase. Additionally, RNA polymerase increases the overall stability of this process by acting as a link between the RNA and DNA strands. New nucleotides that are complementary to the DNA template strand are added to the 3' end of the RNA