Kozak sequence ·真核mRNA上的一个保守序列：ccRcccAUGG,其中R是 一种嘌呤（腺嘌呤和鸟嘌呤），处于起始密码子AUG的上 游三个碱基处，之后是另一个G； ·Kozak sequence在翻译的起始过程中起着重要的作用：
Kozak sequence • 真核mRNA上的一个保守序列：ccRcccAUGG ，其中R是 一种嘌呤（腺嘌呤和鸟嘌呤）, 处于起始密码子AUG的上 游三个碱基处，之后是另一个G； • Kozak sequence在翻译的起始过程中起着重要的作用；
poly-A tail SAAAAAAAAAAAAAAA3 8 poly-A binding 5'cap start(AUG) protein stop(AGU) Copyright 2004 Pearson Education,Inc.,publishing as Benjamin Cummings
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1-4 The genetic code遗传密码 编码蛋白质20个氨基酸的一套三联体密码子； 共有64个密码子，其中61个密码子编码20个氨基酸： This means that the code is highly degenerate; AUG is start codon;UAA,UAG and UGA are stop codons
1-4 The genetic code 遗传密码 • 编码蛋白质20个氨基酸的一套三联体密码子； • 共有64个密码子，其中61个密码子编码20个氨基酸； This means that the code is highly degenerate; • AUG is start codon; UAA, UAG and UGA are stop codons；
second position U A G UUU UCU UAU UGU Phe Tyr Cys UCC UAC UGC Ser UUA UCA UAA stop UGA stop A Leu UUG UCG UAG" stop UGG Trp G CUU CCU CAU CGU U CAC His CUC CCC CGC Leu Pro Arg CUA CCA CAA CGA A GIn CUG CCG CAG CGG G AUU ACU AAU AGU AUC AAC Asn Ser AGC third position(3'end) lle ACC Thr AUA ACA AAA AGA Lys Arg AUGI Met ACG AAG AGG G GUU GCU GAU GGU U GAC Asp GUC GCC GGC Val Ala GUA GCA GAA GAA Gly A Glu GUG GCG GAG GGG G Chain-terminating or"nonsense"codons t Also used in bacteria to specify the initiator formyl-Met-tRNAIMet Copyright 2004 Pearson Education,Inc.,publishing as Benjamin Cummings
Three rules >Codons are read in a 5'to 3'direction in units of three nucleotides; Codons are nonoverlapping and the message contains no gaps; The message is translated in a fixed reading frame which is set by the initiation codon;
Three Rules ➢ Codons are read in a 5’ to 3’ direction in units of three nucleotides; ➢ Codons are nonoverlapping and the message contains no gaps; ➢ The message is translated in a fixed reading frame which is set by the initiation codon;