UC Biologia Molecular Past Paper PDF
Document Details
Uploaded by BenevolentZinc
Universidade de Aveiro
S. Mendo
Tags
Summary
This document provides an overview of the translation process in prokaryotes and eukaryotes. It includes details of mechanisms, tRNA, ribosomes, and regulation. Diagrams and tables are included to illustrate the process.
Full Transcript
UC Biologia Molecular| Ano lectivo 24_25 Parte II| Aula: 5 10 e 11 dezembro Sumário: Etapas do processo de tradução em procariotas e eucariotas. Mecanismos que controlam o rigor do processo de tradução. tRNA iniciador inicia a cadeia polipeptídica. Varrimento da subunidade pequena do ribossoma à pr...
UC Biologia Molecular| Ano lectivo 24_25 Parte II| Aula: 5 10 e 11 dezembro Sumário: Etapas do processo de tradução em procariotas e eucariotas. Mecanismos que controlam o rigor do processo de tradução. tRNA iniciador inicia a cadeia polipeptídica. Varrimento da subunidade pequena do ribossoma à procura de locais de iniciação de eucariotas. Translocação dos ribossomas. Centros activos dos ribossomas. Regulação da tradução. Manipulação da tradução. Stages of the translation process in prokaryotes and eukaryotes. Mechanisms that control the translation process. Initiator tRNA initiates the polypeptide chain. Scanning the small subunit of the ribosome for eukaryotic initiation sites. Translocation of ribosomes. Active centres of ribosomes. Translation regulation. Translation manipulation. 1 S. Mendo| BM24_25 The mRNA circuit ✓3 locations for cytoplasmic mRNA Stress granules Polybosomes, translation factors and ribosomes P-bodies 2 S. Mendo| BM24_25 The process of mRNA translation 3 S. Mendo| BM24_25 Dimensions of the components of the translation apparatus ✓ ~65% rRNA ✓ ~35% ribossomal proteins (L1, L2…: large subunit; S1, S2…: small subunit) 4 S. Mendo| BM24_25 Three stages of translation ✓Initiation (Prokaryotes: IFs; Eukaryotes: eIFs) ✓Elongation (Prokaryotes: EFs; Eukaryotes: eEFs) ✓Termination /release: (Prokaryotes: RFs; Eukaryotes: eRFs) 5 S. Mendo| BM24_25 Three stages of translation ✓ The ribosome has three tRNA-binding sites. An aminoacyl-tRNA enters the A site. Peptidyl-tRNA is bound in the P site. Deacylated tRNA exits via the E site. ✓ Two sites for binding charged tRNAs. 6 S. Mendo| BM24_25 Controlling the accuracy of translation ✓ Pretty accurate: 1 error every 104 -105 ; determined by speci c mechanisms at each stage. ✓ The polymerase inserts a wrong base ✓ Synthetases may attach a wrong tRNA to an aa ✓ Ribosome may allow binding of a tRNA not corresponding to the codon in the A site (most common error) - Wrong substrates are rejected; only correct ones are accepted: 4 bases, one of 20 aa and 1/30-50 tRNAs - error rates of mRNA transcription are low:
