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.

you are certainly talking about this picture:

a: is the label of the white square, it is showing the  replication fork, formed by helicase (d) ==> so it is the site of dna separation and replication 

b: is a new dna brand that is following directly the replication fork, so it is continuous ==> built continuously from 5' to 3

c: dna polymerase cannot replicate dna on its own, it needs the of their proteins, and one of them plays the role of a clamp which fixes  the dna with the dna template and increases  the processivity of the enzyme. ==>   stops polymerase from falling off the  template.

d: is the enzyme responsible for forming the replication fork (helicase) ==> unwinds and separates dna into two strands

e: is the delayed strand, it is built  in the opposite sense of the helicase, so dna will be built in fragments ==> built  fragments from 5' to 3 joins

and finally f: is the enzyme that builds  the new dna strand (dna polymerase) ==>   adds nucleotides to make a new dna helix.

credit: gradman555p98x9p

read more on -