CH 4 - Translation and Protein Structure

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Jun 2, 2023
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CCIHIAAPPTT E- 44 4. I - Molecular Structure of Proteins The bond between two amino acids is known as a peptide bond , when the bond is formed , water is released Polymer of amino acids connected by peptide bonds are known as polypeptides Primary Structure - sequence of amino acids in a protein Secondary Structure - Interaction between stretches ; caused by hydrogen bonding in the polypeptide backbone Tertiary Structure - 3D structure ; results from interactions between amino acid side chains ( e. g. Spatial distribution of hydrophilic anchor hydrophobic R groups ) Quaternary Structure - individual polypeptides that interact with each other ; can be formed by polypeptide subunits coming together ( e. g. Hemoglobin ) Chaperones are proteins that help protect slow - folding or denatured proteins until they can retain their 3D structures ; binds with hydrophobic groups and nonpolar R groups to shield them from innapropriate aggregation
4. 2- Protein Synthesis In Prokaryotes , translation occurs immediately after . In Eukaryotes , translation occurs in the cytoplasm Three binding sites for tRNAs " " " " ¥ É } Binding sites SMALL SUB A Codons are three adjacent nucleotides Anti codons are part of tRNAs that base pair with the corresponding codons of mRNA Enzymes known as aminoacyl tRNA synthase are responsible for translating the codon sequence AUG codon - MET ; start of translation o UAA , UAG , UGA - STOP codons INITIATION , ELONGATION , and TERMINATION Initiation - AUG codon is recognized , MET is established as first amino acid Elongation - successive amino acids are added to the growing chain Termination - addition of amino acids is stopped , the completed polypeptide chain is released from the ribosome
Initiation of translation requires a number of protein initiation factors that bind to mRNA Elongation is assisted by elongation factors which are bound to GTP molecules ; break their high energy bonds to provide energy for elongation of polypeptide Release factor binds to A site which causes termination Operon related to polycistronic mRNA 4. 3- Protein Origins and Evolution 0 Folding Domain folds independent from the rest of the protein Mutations are carried or eliminated based on a process of selection ; what would give an organism the most
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