Chapter4Part2Powerpoint 11.45.23 PM

Chapter4Part2Powerpoint 11.45.23 PM - CHAPTER 4, PART 2...

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Unformatted text preview: CHAPTER 4, PART 2 FLOW OF GENETIC INFORMATION CHAPTER 4, PART 2: FLOW OF GENETIC INFORMATION LECTURE TOPICS 1. RNA properties in general 2. Transcription: RNA Polymerase 3. mRNA properties 4. Genetic Code 5. Eucaryotic genes: structural organization RNA is usually a single-stranded polynucleotide Single-Stranded DNA and RNA can form helical hairpins Complementary when reversed (fold back and base pair) 3` 5` 3` 5` 5` 3` 5` 3` Stem-loop (hairpin) structures [Fig.5.19] Typical highly base-paired RNA structure (----) Extra H-bonds (----) Watson-Crick H-bonds in (G-C) base pair 3 bases form H-bonds * * * * * * * [p.126 and Fig.5.20] ends • All RNA in E. coli (a bacterium) is made by one RNA polymerase • mRNA encodes protein amino acid sequences Types of cellular RNA molecules The “Central Dogma” of molecular biology DNA RNA PROTEIN Replication Reverse DNA virus Retrovirus RNA Virus Transcription translation transcription Prions 10 -4,-5 10-8 10-3, -4 10-4 FEATURES OF PROCESSES ¾ Accuracy - RELATIVE ¾ Signals - STARTS AND STOPS ¾ Stages - INITIATION, ELONGATION, TERMINATION = error rates 2) TRANSCRIPTION: DNA Æ RNA RNA polymerase makes RNA that is complementary to a DNA template strand Coding strand DNA sequence is same as mRNA (or any RNA transcript), but has T’s instead of U’s TRANSCRIPTION: DNA Æ RNA RNA polymerase: DNA-dependent enzymes which require: A. A template DNA (preferably double-stranded) B. Activated precursors (all 4 rNTPs – ATP, GTP, CTP, UTP) C. Mg ++ D. Reaction is: (RNA) n + rNTP (RNA) n+1 + PPi 2Pi E. Same reaction mechanism as DNA polymerase F. RNA polymerase does not require a primer RNA polymerase reaction mechanism: (same as DNA polymerase) 3`-OH attacks α-P 3` 3` 5` 5` Nucleophilic attack New 3` Æ 5` phosphodiester bond •...
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This note was uploaded on 12/16/2011 for the course BIOLOGY 101 taught by Professor Mr.wallace during the Fall '11 term at Montgomery College.

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Chapter4Part2Powerpoint 11.45.23 PM - CHAPTER 4, PART 2...

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