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 Theory of natural selection was proposed by Charles Darwin in 1858. Darwin believed all plants and animals had evolved from a few common ancestors by means of natural selection. Plants and animals produce many offspring, but some of the young die before they can become parents. According to Darwin's theory, natural selection determines which members of a species die prematurely and which ones survive and reproduce. All living things must compete for a limited supply of food, water, space, and other necessities.