Gene Structure and Function Gene and How They Work Chapter 15 Topics you are not responsible for: SRP-RNA Detailed structure of bacterial and eukaryotic RNA polymerases, and tRNAs, ribosomes, and spliceosomes specific promoter sequences Alternative splicing End of Chapter questions: Understand: all Apply: all Synthesize: 1 - 3 Do all mQuiz questions Gene Structure and Function

Gene Structure and Function How is genetic information used? “Transcription” of code from DNA to RNA “Translation” of code from RNA into A.A. sequence Gene Structure and Function

Gene Structure and Function How are genes arranged on DNA? Template strand vs complementary strand What are the functional regions of a gene? Gene Structure and Function

Gene Structure and Function How does RNA transcription occur? How does RNA polymerase ‘know’ where to begin? Promoters -- RNA polymerase binding site … and gene regulation How does RNA polymerase ‘know’ where to end? Gene Structure and Function

Gene Structure and Function How does transcription proceed? Binding to promoter Opening of helix Complementary base-pairing Concurrent transcription Transcription Transcription - 2 Gene Structure and Function

What are the functions of RNA? mRNA tRNA rRNA (other types, e.g. snRNA, iRNA) In eukaryotes, How is mRNA modified before existing the nucleus? Stabilizing the transcript 5’ capping 3’ poly-A tail Removal of introns Review Differences in RNA and DNA Structures (Chapter 3) Gene Structure and Function

Gene Structure and Function How are introns removed? “RNA processing” Introns & Exons “snRNPs” & spliceosomes Can be many introns Gene Structure and Function

Gene Structure and Function Where does translation occur? Export to the cytosol What is the Genetic code? Codons specify AAs How many codons? How many AAs? -- Redundancy Starting position Ending position Gene Structure and Function

Gene Structure and Function Where is translation initiated and terminated? Start Codons & Stop Codons What is the “Reading Frame”? Gene Structure and Function

Gene Structure and Function What is the structure of ribosomes? Large and small subunits rRNA and protein constituents tRNA binding sites Model Gene Structure and Function

Gene Structure and Function What is the structure of tRNA? Anticodons ‘Charging’ of tRNAs -- aminoacyl tRNA synthestases Model Translation video Gene Structure and Function

What are the 3 stages of translation? Initiation -- formyl methionine -- ‘fMet’ Elongation -- elongation factors Termination -- release factor Initiation Virtual cell animation Gene Structure and Function

Ribosome translocates How does the peptide pass between tRNAs during translation? Peptide chain on tRNA in P-site is passed new t-RNA Ribosome translocates 1 codon, and t-RNA exists from E-site New t-RNA enters at the A-site Gene Structure and Function

Gene Structure and Function What happens during translation termination stage? Termination Gene Structure and Function

Gene Structure and Function What are effects of different types of mutations on gene function - I? What is a “Missense” mutation? What is a “Nonsense” mutation? Gene Structure and Function

Gene Structure and Function What are effects of different types of mutations on gene function – II ? What causes a “Frameshift” mutation? What is a “Silent” mutation? Gene Structure and Function