The leucine-enkephalin binds to the opioid receptors they function as important signaling molecules in the brain. There are four peptide bonds present in them. These are endogenous ligands which act as neurotransmitters and they have morphine like activity that is they suppress the brain pain receptors and depress the central nervous system and provide relief in pain.
Answer - A Prokaryotic cells, being unicellular organisms, do not have a defined nucleus. They have a nucleoid in place of the nucleus which is formed of a single chromosome consisting of double stranded DNA.
