参与蛋白质生物合成的物质包括 ·三种RNA -mRNA(messenger RNA,信使RNA) -rRNA(ribosomal RNA,核蛋白体RNA) -tRNA(transfer RNA,转移RNA) ·20种氨基酸(AA)作为原料 。酶及众多蛋白因子,如IF、eIF ·ATP、GTP—供能物质 ·无机离子,如Mg2+
(一)蛋白质合成的模板mRNA 从mRNA5'端起始密码子AUG到3'端终 止密码子之间的核苷酸序列,各个三联体密 码连续排列编码一条多肽链,称为开放阅读 框架(open reading frame,ORF)。 ORF. 5 30 mGppp AUG UAA AAA.A S'非翻译区UTR 3'非翻译区UTR
(一)蛋白质合成的模板mRNA UTR UTR
Poly(U)编码Poly Phe UUU→Phe CCC→Pro AAA→Lys AAGAAGAAGAAG AAGAAG. UCUCUCU C UCU CU C U a Ser—Leu-Ser-Leu -Ser
第二个字母 U C Y G 遗传密码表 UUU Phe UCU Ser UAU Tyr UGU Cys UUC Phe UCC Ser UAC Tyr UGC Cys 密 UUA Leu UCA Ser UAA Stop UGA Stop UUG Leu UCG Ser UAG Stop UGG 码 Trp CUU Leu CCU Pro CAU His CGU Arg CUC Leu CCc Pro CAC His CGC Arg 的 CUA Leu CCA Pro CAA GIn CGA Arg CUG Leu CCG Pro CAG GIn CGG Arg 第 AUU nle ACU Thr AAU Asn AGU Ser AUC ne ACC Thr AAC Asn AGC Ser AUA ne ACA Thr AAA Lys AGA Arg AUG Met ACG Thr AAG Lys AGG Arg 字 GUU Val GCU Ala GAU Asp GGU Gly 母 GUC Val GCC Ala GAC Asp GGC Gly GUA Val GCA Ala GAA Glu GGA Gly GUG Val GCG Ala GAG Glu GGG Gly 目录
密码的特点1一连续性 aa aa aa,aa aa11 aa139a15 AN UCICG GAIA AICU CICIU UIUIC AIGIC CICIU CIAIUC aaa aa12 a814 (a)Overlapping code.There will be statistical regularities between adjacent amino acid residues.Point mutations (red)will be able to change two amino acid residues aa1 a32 a33 a34 aas aas UCCIGIG A AIAIC U CICIU U UICIA G CICICIU CIAIUC (b)Punctuated code.Deletions of four nucleotides (or multiples thereof)will restore the reading frame aa1 a32 aa4 aas aa6 aa aas UCCIG G AIA A CIU C CIU U UIC A GIC C CIU C AIUC (c)Unpunctuated code.Deletions of three nucleotides (or multiples thereof)will restore the reading frame.This is the actual form of the code
密码的特点1—连续性