蛋白質(zhì)生物合成(1)-資料下載頁(yè)
2025-01-07 07:57本頁(yè)面
【正文】 code is maless and degenerate。 the first two nucleotides of the threeletter code are often sufficient。 and there are special codons for the initiation and termination of peptide synthesis. ? 2. An aminoacyltRNA synthetase catalyzes the addition of a specific amino acid to the acceptor stem of the appropriate tRNA, producing an aminoacyltRNA. ? 3. Ribosomes are the RNAprotein plex. The growing polypeptide chain is attached to a tRNA in the peptidyl (P) site of the ribosome, and the aminoacyltRNA molecule bearing the next amino acid to be added to the nascent polypeptide chain docks in the aminoacyl (A) site. ? 4. Translation begins with the formation of an initiation plex consisting of an initiator tRNA, the mRNA template, the ribosomal subunits, and several initiation factors. In prokaryotes, initiation occurs just downstream of ShineDalgarno sequence. ? 5. The elongation step of translation requires accessory proteins called elongation factors. The three steps of elongation are(1)positioning of the correct aminoacyltRNA in A site, (2)formation of the peptide bond by peptidyl transferase, and (3) translocation of the ribosome by one codon. ? 6. Release factors recognize termination codons and catalyze the termination of protein synthesis and disassembly of the translation plex. ? 7. Many proteins are posttranslationally modified. Some eukaryotic proteins destined for secretion containing Nterminal signals. 蛋白質(zhì)生物合成 ? mRNA、 tRNA、 rRNA的作用 ? 遺傳密碼的四個(gè)特點(diǎn)；重點(diǎn)簡(jiǎn)并性、擺動(dòng)性 ? 起始密碼、終止密碼 ? 以原核生物為例，說(shuō)明蛋白質(zhì)生物合成的過(guò)程（包括各種酶及蛋白質(zhì)因子）。 ? 分泌性蛋白 ? 信號(hào)肽
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