In genetics

Genetics

Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....

, a promoter is a region of DNA

DNA

Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...

 that facilitates the transcription

Transcription (genetics)

Transcription is the process of creating a complementary RNA copy of a sequence of DNA. Both RNA and DNA are nucleic acids, which use base pairs of nucleotides as a complementary language that can be converted back and forth from DNA to RNA by the action of the correct enzymes...

 of a particular gene

Gene

A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

. Promoters are located near the genes they regulate, on the same strand and typically upstream

Upstream and downstream (DNA)

In molecular biology and genetics, upstream and downstream both refer to a relative position in DNA or RNA. Each strand of DNA or RNA has a 5' end and a 3' end, so named for the carbons on the deoxyribose ring. Relative to the position on the strand, downstream is the region towards the 3' end of...

 (towards the 5' region of the sense strand

Sense strand

In genetics, a sense strand or coding strand is the segment of double stranded DNA running from 5' - 3' that is complementary to the antisense strand or template strand...

).
In order to for the transcription to take place, the enzyme that synthesizes RNA, known as RNA polymerase

RNA polymerase

RNA polymerase is an enzyme that produces RNA. In cells, RNAP is needed for constructing RNA chains from DNA genes as templates, a process called transcription. RNA polymerase enzymes are essential to life and are found in all organisms and many viruses...

, must attach to the DNA near a gene. Promoters contain specific DNA sequences and response elements which provide a secure initial binding site for RNA polymerase and for proteins called transcription factors that recruit RNA polymerase.