1. 15.1 Many Genes Encode Proteins The One Gene One Enzyme Hypothesis: Genes function by encoding enzymes, and each gene encodes a separate enzyme. More specific: one gene one polypeptide hypothesis

4. Concept Check 1 Auxotrophic mutation 103 grows on minimal medium supplemented with A, B, or C. Mutation 106 grows on medium supplemented with A and C, but not B; and mutation 102 grows only on medium supplemented with C. What is the order of A, B, C in a biochemical pathway?

5. Concept Check 1 Auxotrophic mutation 103 grows on minimal medium supplemented with A, B, or C. Mutation 106 grows on medium supplemented with A and C, but not B; and mutation 102 grows only on medium supplemented with C. What is the order of A, B, C in a biochemical pathway? B  A  C

6. 15.2 The Genetic Code Determines How the Nucleotide Sequence Specifies the Amino Acid Sequence of a Protein

7. Breaking the Genetic Code

10. Codon: a triplet RNA code Breaking the Genetic Code

11. Degenerate code: Amino acid may be specified by more than one codon. Synonymous codons: codons that specify the same amino acid Isoaccepting tRNAs: different tRNAs that accept the same amino acid but have different anticodons Wobble hypothesis The Degeneracy of the Code

14. Sense codons: encoding amino acid Initiation codon: AUG Termination codon: UAA, UAG, UGA The Degeneracy of the Code

16. Concept Check 2 Through wobble, a single can pair with more than one. a.codon, anticodon b.group of three nucleotides in DNA, codon in mRNA c.tRNA, amino acid d.anticodon, codon

17. Concept Check 2 Through wobble, a single can pair with more than one. a.codon, anticodon b.group of three nucleotides in DNA, codon in mRNA c.tRNA, amino acid d.anticodon, codon

18. 15.1 Many Genes Encode Proteins The One Gene One Enzyme Hypothesis: Genes function by encoding enzymes, and each gene encodes a separate enzyme. More specific: one gene one polypeptide hypothesis

19. 15.2 The Genetic Code Determines How the Nucleotide Sequence Specifies the Amino Acid Sequence of a Protein

20. Reading frame: three ways in which the sequence can be read in groups of three. Each different way of reading encodes a different amino acid sequence. Nonoverlapping: A single nucleotide may not be included in more than one codon. The universality of the code: near universal, with some exceptions The Reading Frame and Initiation Codons

21. 15.3 Amino Acid Are Assembled into a Protein Through the Mechanism of Translation

22. Aminoacyl-tRNA syntheses and tRNA charging The specificity between an amino acid and its tRNA is determined by each individual aminoacyl-tRNA synthesis. There are exactly 20 different aminoacylt-tRNA syntheses in a cell. The Binding of Amino Acids to Transfer RNAs

23. Initiation factors IF-3, initiator tRNA with N- formylmethionine attached to form fmet-tRNA Energy molecule: GTP The Initiation of Translation

26. The Shine–Dalgarno consensus sequence in bacterial cells is recognized by the small unit of ribosome. The Kozak sequence in eukaryotic cells facilitates the identification of the start codon. The Initiation of Translation

27. Exit site E Peptidyl site P Aminoacyl site A Elongation factors: Tu, Ts, and G Elongation

29. Concept Check 3 In elongation, the creation of peptide bonds between amino acids is catalyzed by. a.rRNA b.protein in the small subunit c.protein in the large subunit d.tRNA

30. Concept Check 3 In elongation, the creation of peptide bonds between amino acids is catalyzed by. a.rRNA b.protein in the small subunit c.protein in the large subunit d.tRNA

31. Termination codons: UAA, UAG, and UGA Release factors Termination

37. The three-dimensional structure of the ribosome Polyribosomes: –An mRNA with several ribosomes attached 15.4 Additional Properties of RNA and Ribosomes Affect Protein Synthesis

39. Messenger RNA surveillance: Detect and deal with errors in mRNA Nonsense – mediated mRNA decay: eliminating mRNA containing premature termination codons The posttranslational modifications of proteins 15.4 Additional Properties of RNA and Ribosomes Affect Protein Synthesis