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. ...
Darwin also described a form of natural selection that depends on an organism's success at attracting a mate, a process known as sexual selection. The colorful plumage of peacocks and the antlers of male deer are both examples of traits that evolved under this type of selection.