Your heart then pumps it through your body to provide oxygen to the cells of your tissues and organs. As the cells use the oxygen, carbon dioxide is produced and absorbed into the blood. Your blood then carries the carbon dioxide back to your lungs, where it is removed from the body when you exhale.
DNA polymerase has 5'-3' activity. All known DNA replication systems require a free 3' hydroxyl group before synthesis can be initiated (note: the DNA template is read in 3' to 5' direction whereas a new strand is synthesized in the 5' to 3' directionâthis is often confused).
A transcription unit is a linear sequence of DNA that extends from a transcription start site to a transcription stop site (Figure 4). Figure 4. The promoter, a DNA sequence that lies upstream of the RNA coding region, serves as an indicator of where and in which direction transcription should proceed.The promoter is not actually transcribed; its role is purely regulatory.he terminator, a sequence of nucleotides at the end of the transcription unit, is transcribed along with the RNA coding region. The terminator serves as a speed bump of sorts; transcription stops only after this region has been transcribed.