GENETICS AND EVOLUTION
MOLECULAR BASIS OF INHERITANCE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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It codes for methionine only
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It is also an initiation codon
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It codes for methionine in both prokaryotes and eukaryotes
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All of the above
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Detailed explanation-1: -AUG codon codes for the methionine whereas GUG also functions as a start codon. These start codons always codes for the methionine and they are universal and codes for the same in both eukaryotes and prokaryotes. Hence, the correct answer is option (D).
Detailed explanation-2: -The codon AUG is called the START codon as it the first codon in the transcribed mRNA that undergoes translation. AUG is the most common START codon and it codes for the amino acid methionine (Met) in eukaryotes and formyl methionine (fMet) in prokaryotes.
Detailed explanation-3: -One “start” codon, AUG, marks the beginning of a protein and also encodes the amino acid methionine.
Detailed explanation-4: -For example, the sequence AUG is a codon that specifies the amino acid methionine.
Detailed explanation-5: -Then a transfer RNA (tRNA) molecule carrying the amino acid methionine binds to what is called the start codon of the mRNA sequence. The start codon in all mRNA molecules has the sequence AUG and codes for methionine.