The final phase of translation, called termination, is signaled by three nucleotides, called a , that mark the end of a polypeptide chain. intron exon plasmid stop codon

The correct answer is "stop codon"

Explanation:

Codon is a trinucleotide (three nucleotides) sequence that translates to a specific amino acid or stops the translation of genetic sequence to amino acids. There is a codon table that is usually used to determine the corresponding protein.

However, a sequence of DNA or RNA sequence will have 3 nucleotides (codons) each been translated to a specific amino acid. For example, the sequence below can be translated as follows

5' - UAUGGAUUUAGACACUAG -3'

UAU - Tyrosine

GGA -Glycine

UUU - Phenylalanine

AGA - Arginine

CAC - Histidine

UAG - stop codon

The stop codon is a codon that doesn't code for any amino acid and signals the stop of protein synthesis/gene translation of a sequence. There are three stop codons which are UAG, UGA and UAA.

the answer that best describes the relative refractory period in the neuron is the resting membrane potential is restored, but concentrations of sodium and potassium are not restored to their original state.

the refractory period is the time during which another stimulus given to the neuron will not lead to a second potential. thus, because na+ channels are inactivated during this time, additional depolarizing stimuli do not lead to new action potentials.  

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