BIOLOGY
NUCLEIC ACIDS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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This always reads:AUG, This begins every polypeptide chain, This codes for methionine, If a missense mutation occurs in this codon, the protein will never be translated
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This is a set of 3 nucleotides on mRNA
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This is a set of 3 nucleotides on tRNA
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None of the above
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Detailed explanation-1: -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-2: -The standard start codon for translation of a gene is “AUG, ” which encodes the amino acid methionine (Met or M), and establishes the reading frame for the ribosome to follow, adding corresponding amino acids in a polypeptide chain.
Detailed explanation-3: -The start codon in all mRNA molecules has the sequence AUG and codes for methionine. Next, the large ribosomal subunit binds to form the complete initiation complex. During the elongation stage, the ribosome continues to translate each codon in turn.
Detailed explanation-4: -The AUG codon is usually within the context of a slightly larger sequence, called the Kozak consensus sequence, which generally has the sequence GCCACCAUGG (the underlined adenine can also be a guanine). AUG codes for the amino acid methionine, and so all protein translation begins with methionine. Figure 3.17.