Chapter 4 Protein Structure RNA Translation Protein Production Part 1 Protein Structure I Amino Acids A Monomers with tetrahedral structure fig 4 1 B 20 different ones C Amino acids linked buy forming a peptide bond via dehydration fig 4 3 AA chain II Primary structure III Secondary Structure between a carbonyl group of 1 AA amide group of another A R groups not involved B Alpha helix each carbonyl group H bonds with an amide group 4 repeating folding patterns stabilized by H bonds amino acids ahead in the chain fig 4 6 C Beta pleated sheet the polypeptide folds back on itself and H bonds form between carbonyl groups in 1 chain and amide groups in the other chain fig 4 7 IV Tertiary structure polypeptide folds into a 3D shape because of R group interactions A Can be final structure but not always functional multimeric protein A Subunits of proteins with quat structure may be identical or 2 polypeptides associate to form a V Quaternary structure different from each other 1 Sequence of bases in a codon specifies an amino acid an amino acid AND start or stop 2 Each base only part of 1 codon code doesn t overlap Part 2 Translation I Translation mRNA A 3 bases 1 codon protein II Equipment required for translation A mRNA fig 3 22 not here introns exons poly A tail 1 2 3 end poly A tail 5 end 5 cap B Ribosome 1 Complexes of protein rRNA that form the environment for translation 2 Looks like hamburger bun a When mRNA comes in the large small subunits of ribosome come together around strand of mRNA C tRNA 1 Brings specific AA to the ribosome 2 Ensures the right AA gets matched to the right codon 3 Structure a Entire thing is single strand but mostly folded over on itself and twisted to look like ribbon model b Top single stranded where amino acid attaches c Bottom 3 bases called anticodon i Opposite in polarity complementary to the mRNA 4 To pick up an amino acid tRNA interacts with a specific type of enzyme forming charged tRNA holding covalently bonded AA 5 Fig 4 14 AA attaches at small top part D Sets of proteins 1 Proteins to help start translation initiation factors keep it going elongation factors or end it release factors III 3 stages if translation A Initiation 1 Initiation factors bring the equipment for translation together 2 Don t know order fig 4 17 a b just know how it 1 Ribosome moves down mRNA as amino acids are added 2 Starts at 5 end ribosome moves towards 3 end of all comes together B Elongation to the polypeptide mRNA C Termination 3 Fig 4 15 great base pairing occurs between the tRNA mRNA codon 1 At stop codon protein release factor binds to ribosome breaking bond between the last tRNA the polypeptide IV Gene Expression A Making a product from a gene B Genes that code for RNA products run transcription mRNA final product C Genes that code for proteins run transcription then translation V See end of chapter 4 pages 4 16 4 17
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