Stem cell transplants may someday be used to treat Parkinson's disease. Researchers are hopeful that these cells would alleviate the symptoms of Parkinson's disease by

Researchers are hopeful that these cells would alleviate the symptoms of Parkinson's disease by secreting the neurotransmitter dopamine.

Explanation:

Dopamine is a neurotransmitter released by the brain that plays a role in pain processing at various levels of the central nervous system. This includes the spinal cord, periaduectal gray matter, the thalamus, the basal ganglia, the insular cortex, and the cingulate cortex. Low dopamine levels are associated with the painful symptoms that frequently occur in Parkinson's disease. Parkinson's is generated from a neurodegenerative disorder that mainly affects dopaminergic neurons, responsible for producing and secreting dopamine within the brain. When these neurons degenerate, dopamine levels decrease and the consequences are tremor, muscle stiffness and difficulty making voluntary movements, among others.  In Parkinson's disease, there is a loss of dopaminergic neurons and a potential treatment would be that the lost neurons could somehow be replaced. One possibility is to transplant stem cells that differentiate into dopamine-producing nerve cells.

currents is the correct answer.

step 1: initiation

initiation is the beginning of transcription. it occurs when the enzyme rna polymerase binds to a region of a gene called the promoter. this signals the dna to unwind so the enzyme can ‘‘read’’ the bases in one of the dna strands. the enzyme is now ready to make a strand of mrna with a complementary sequence of bases.

step 2: elongation

elongation is the addition of nucleotides to the mrna strand. rna polymerase reads the unwound dna strand and builds the mrna molecule, using complementary base pairs. there is a brief time during this process when the newly formed rna is bound to the unwound dna. during this process, an adenine (a) in the dna binds to an uracil (u) in the rna.

step 3: termination

termination is the ending of transcription, and occurs when rna polymerase crosses a stop (termination) sequence in the gene. the mrna strand is complete, and it detaches from dna.