From DNA to Protein1 Chapter 7 -- Transcription and Translation Questions in this chapter you should be able to answer: Chapter 7- #s , 16A,C,D, 17 There are several good animations on the The Virtual Cell web site  watch them

From DNA to Protein2 There are many steps between DNA & Protein

From DNA to Protein3 What are the key events during transcription? Begins at Promoter Ends at terminator σ-factor is required in prokaryotes Jmol-RNA polymerase Jmol-RNA polymerase Transcription

From DNA to Protein4 What is a promoter? For example, in prokaryotes… Consensus sequences σ-factor Orientation Initiation site Jmol σ-factor on DNA Jmol σ-factor on DNA Virtual Cell Animation

From DNA to Protein5 Transcription in Eukaryotes is more complex Two concepts for now… 1)3 RNA polymerases RNA polymerase I RNA polymerase II RNA polymerase III 2) General transcription factors Some bind to “TATA-box” 5’-TATAAA-3’ consensus sequence  initiation complex Some bind to RNA polymerase II  polymerase phosphorylation

From DNA to Protein6 Either strand may carry template sequence Another question: From an evolutionary perspective, why don’t overlapping genes occur? Question 7-2 In what direction are the RNA polymerases moving in this image?

From DNA to Protein7 What happens to mRNA after (as) it is transcribed? Capping RNA processing Polyadenylation Export Translation

From DNA to Protein8 What is 5’ capping and polyadenylation? Poly-A tail protects against RNAse (function is sort of like a telomere)

From DNA to Protein9 How does RNA processing occur? snRNPs, Spliceosomes and Ribozymes RNA Processing

From DNA to Protein10 Is an mRNA always processed in the same way? -- “alternative splicing” -- can be very complex…

From DNA to Protein11 How do mRNAs get to the cytosol? Only properly processed RNAs allowed out Why doesn’t this process involve importins and nucleoporins that we discussed earlier?

From DNA to Protein12 What is the structure of the ribosome? What are the functions of the A, P & E sites? Jmol - Ribosome

From DNA to Protein13 What is the structure of tRNAs? Anticodon 3’ AA binding site ‘Charging’ How many tRNAs? in humans -- wobble allows some to fit 2 or more codons tRNA model

From DNA to Protein14 How is translation initiated? Orientation Initiation complex Finding start codon Add LSU Translation

From DNA to Protein15 How does elongation and termination proceed? Passing of peptide From P- to A-site tRNAs Ribosome translocation Release factor Polyribosome Elongation

From DNA to Protein16 RNA and the evolution of Life Why RNA as start of evolution? 1) Has genotype & phenotype 2) Could have self-replicated

From DNA to Protein17 What is the evidence for the RNA world? Central roles of ribonucleotides -- m-,t- r-RNAs -- ribozymes -- ribosome catalysis -- miRNAs -- telomerase -- ATP, NADH, etc Experimental demonstrations

From DNA to Protein18 Why did DNA evolve as the repository for genetic information? Why is it genetically more stable? Why is it chemically more stable?

From DNA to Protein19 Why does DNA contain thymine instead of uracil?