Organisms of all three domains of life usually use the mRNA codon AUG as the start codon.
Do organisms of the three domains use the same amino acid as the initial amino acid in translation?
Identify similarities and differences.
Select the three correct answers.
Eukarya initiate translation using tRNA attached to formyl-methionine.
Archaea initiate translation using tRNA attached to methionine.
Bacteria initiate translation using tRNA attached to formyl-methionine.
Archaea initiate translation using tRNA attached to formyl-methionine.
Bacteria initiate translation using tRNA attached to methionine.
Eukarya initiate translation using tRNA attached to methionine.
Despite AUG being the most common start codon sequence, very few proteins have methionine as the first amino acid. Why is this the case?
Select the two correct answers.
Methionine contains an unstable sulphur atom and is prone to spontaneous decay.
Processing events (for example, removal of the signal sequence) expose internal amino acids at the amino terminus of the mature polypeptide.
Because sometimes other start codons are used which code for amino acids other than methionine or formyl-methionine.
Removal of the formyl-methionine (or methionine) exposes the second amino acid at the amino terminus of the mature polypeptide.
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