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From DNA to Protein Chapter 7 -- Transcription and Translation. There are several good animations on the The Virtual Cell web site watch them. Questions in this chapter you should be able to answer: Chapter 7- #s 2 - 14, 16A,C,D, 17. There are many steps between DNA & Protein.
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From DNA to Protein Chapter 7 -- Transcription and Translation There are several good animations on the The Virtual Cell web site watch them Questions in this chapter you should be able to answer: Chapter 7- #s 2 - 14, 16A,C,D, 17 From DNA to Protein
There are many steps between DNA & Protein From DNA to Protein
What are the key events during transcription? Begins at Promoter Ends at terminator σ-factor is required in prokaryotes 7.2 Transcription RNA polymerase Jmol model From DNA to Protein
What is a promoter? For example, in prokaryotes… Consensus sequences σ-factor Orientation Initiation site Virtual Cell Animation σ-factor on DNA From DNA to Protein
Transcription in Eukaryotes is more complex Two concepts for now… • 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 Protein
Either strand may carry template sequence Question 7-2 In what direction are the RNA polymerases moving in this image? Question: From an evolutionary perspective, why don’t overlapping genes occur? From DNA to Protein
What happens to mRNA after (as) it is transcribed? Capping RNA processing Polyadenylation Export Translation From DNA to Protein
What is 5’ capping and polyadenylation? Poly-A tail protects against RNAse (function is sort of like a telomere) From DNA to Protein
How does RNA processing occur? Ribozymes, snRNPs and spliceosomes RNA Processing From DNA to Protein
Is an mRNA always processed in the same way? -- “alternative splicing” Question: Will counting the number of promoters yield the number of different proteins produced by the human genome? From DNA to Protein
How do mRNAs get to the cytosol? Why doesn’t this process involve importins and nucleoporins that we discussed earlier? From DNA to Protein
What is the structure of the ribosome? What are the functions of the A, P & E sites? Ribosome model From DNA to Protein
What is the structure of tRNAs? Anticodon 3’ AA binding site ‘Charging’ How many tRNAs? -- 48 in humans -- wobble allows some to fit 2 or more codons tRNA model From DNA to Protein
How is translation initiated? Orientation Initiation complex Finding start codon Add LSU Translation From DNA to Protein
How does elongation and termination proceed? Passing of peptide From P- to A-site tRNAs Ribosome translocation Release factor Elongation Polyribosome From DNA to Protein
RNA and the evolution of Life Why RNA as start of evolution? 1) Have genotype & phenotype 2) Could have self-replicated From DNA to Protein
What is the evidence for the RNA world? Central roles of ribonucleotides -- m-,t- r-RNAs -- ribosome catalysis -- miRNAs --ribozymes -- telomerase -- ATP, etc Experimental demonstrations From DNA to Protein
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 Protein
Why does DNA contain thymine instead of uracil? From DNA to Protein