안녕하세요 학생 ^^

Prokaryotes use a modified form of methionine for the first amino acid. It is known as fmet (formyl-methionine). fmet is used ONLY as the first amino acid of a protein. When AUG appears in the middle of a coding region of an mRNA, methionine (not fmet) is put into the protein. The formyl group is put onto methionine after the methionine is attached to the tRNA. 

prokaroyte이 위와 같이 first methionine을 항상 fMet 을 붙여줍니다. eukaryote 은 그렇지 않죠  The first amino acid put into proteins is methionine, since that is the amino acid specified in the genetic code for the first codon of a protein .  mitochondria는 eukaryote안에 있는 structure로써, eukaryote 처럼 행동하지 않고 맨 첫 aa을 fmet 을 붙여줌으로써 prokaryote처럼 행동하네요. 그래서 endosymbiosis의 증거가 될수 있습니다.