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Answer:
Three nucleotide
Explanation:
Three nucleotides are required to code for one amino acid. There are four types of nucleotides A, T, G, C which make DNA. So a doublet of nucleotide code which involves only two nucleotide would be insufficient to code for 20 amino acids because if 4 different nucleotide is taken two at a time then it can only produce 16 amino acid(4²=16).
But if we take three-nucleotide than the number reaches 64 which is more than sufficient to code for 20 different amino acids(4³= 64). Therefore 3 nucleotides are needed to code for an amino acid.
Other molecules such as proteins, starch and sugar are simply too large to diffuse across the membrane. Sometimes, some of these large molecules are transported across the cell membranes by carrier proteins; this does not require energy and as a result is a form of passive transpor