Neurotransmitters is the word you're looking for.
The boundary separates them<span />
Answer:
The nitrogen cycle could not exist without first nitrogen. The cycle is about this specific element which goes to show that if this element is not present then, there will not be any nitrogen cycle. Also, an important factor for the cycle is the presence of the bacteria and other microorganism which are needed for the fixation.
Stability.
Atoms react with other atoms to be stable.
Answer:
The correct answer is B. DNA helicase first unwinds the double helix around the +1 site.
Explanation:
The helicase is an enzyme that specifically breaks the hydrogen bonds of the bases in the transcription process. As E. Coli is a prokaryote, then, the transcription only occurs in one point of the circular DNA. The promoter region indicates where the DNA polymerase has to start replicating and the Topoisomerase unwinds the parts of the DNA that are being excessively twisted because of the separation of the two strands.