Why must an in vitro observation be confirmed in vivo?
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A. A living thing does not make its own enzymes.
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B. A test tube is exactly like a living cell.
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c. Some enzymes behave unnaturally in a test tube.
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D. Observations in a test tube are easy to make.

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.