BIO311C_Spr11_Chapter_17_part 2

BIO311C_Spr11_Chapter_17_part 2 - Gene Expr ession Figure...

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Unformatted text preview: Gene Expr ession Figure 17.26 TRANSCRIPTION RNA is transcribed from a DNA template. DNA RNA polymerase RNA transcript RNA PROCESSING In eukaryotes, the RNA transcript (pre- mRNA) is spliced and modified to produce mRNA, which moves from the nucleus to the cytoplasm. Exon P o ly- A RNA transcript (pre-mRNA) Intron NUCLEUS C a p FORMATION OF INITIATION COMPLEX After leaving the nucleus, mRNA attaches to the ribosome. CYTOPLASM mRNA P o l y- A Growing polypeptide Ribosomal subunits C a p Aminoacyl-tRNA synthetase Amino acid tRNA AMINO ACID ACTIVATION Each amino acid attaches to its proper tRNA with the help of a specific enzyme and ATP. Activated amino acid TRANSLATION A succession of tRNAs add their amino acids to the polypeptide chain as the mRNA is moved through the ribosome one codon at a time. (When completed, the polypeptide is released from the ribosome.) Anticodon A C C A A A U G G U U U A U G U A C E A Ribosome 1 P o ly- A 5 5 3 Codon 2 3 4 5 Genetic code and tr anslation Chapter 17 (328-331, 337- 342) Codons: Tr iplets of Bases Genetic information is encoded as a sequence of nonoverlapping base triplets, or codons www.wikipedia.org Figure 17.5 Second mRNA base U C A G U C A G UUU UUC UUA UUG CUU CUC CUA CUG AUU AUC AUA AUG GUU GUC GUA GUG Met or start Phe Leu Leu lle Val UCU UCC UCA UCG CCU CCC CCA CCG ACU ACC ACA ACG GCU GCC GCA GCG Ser Pro Thr Ala UAU UAC UGU UGC Tyr Cys CAU CAC CAA CAG CGU CGC CGA CGG AAU AAC AAA AAG AGU AGC AGA AGG GAU GAC GAA GAG GGU GGC GGA GGG UGG UAA UAG Stop Stop UGA Stop Trp His Gln Asn Lys Asp Arg Ser Arg Gly U C A G U C A G U C A G U C A G First mRNA base (5 end) Third mRNA base (3 end) Glu I nitiator or star t codon: AUG Ter mination or stop codons: UAA, UAG, UGA Univer sal genetic code! Char acter istics of Genetic Code A) Genetic code is almost universal B) Genetic code is non-overlapping Genetic code is non-over lapping C) Genetic code is degenerate Degener acy of the genetic code Many codons are redundant: two or more codons can code for the same amino acid....
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This note was uploaded on 08/18/2011 for the course BIO 1406 taught by Professor Bostic during the Spring '09 term at Austin Community College.

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BIO311C_Spr11_Chapter_17_part 2 - Gene Expr ession Figure...

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