Promoter sequences define the direction of transcription and indicate which DNA strand will be transcribed; this strand is known as the sense strand. Many eukaryotic genes have a conserved promoter sequence called the TATA box, located 25 to 35 base pairs upstream of the transcription start site.romoter sequences are typically located directly upstream or at the 5' end of the transcription initiation site.
Popular Answers. Positive selection: also called (Darwinian selection) variants that increase in frequency until they fix in the relevant population. The selective pressure that leads to this fixation is termed positive selection. Negative selection: Also called purifying selection, it means that selection is purging changes that cause deleterious impacts on the fitness of the host. ...
Selection is the process that increases the frequencies of plant resistance alleles in natural ecosystems through coevolution, and it is the process that increases the frequencies of virulence alleles in agricultural ecosystems during boom and bust cycles. Selection occurs in response to a specific environmental factor.