Genetics PP2 (Chapter 10)

So any order of bases is ok change b double helix

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Unformatted text preview: bases is OK change B. Double Helix Model B. 1. History of development 2. Features of Model a. Two sugar-PO4 backbones b. Base-pairing due to weak H bonding b. weak c. Width is even, about 2 nm d. Chains are polar, must go in opposite d. polar must directions directions x Polarity given by 5' and 3' Cs of sugar s 3. DH Model meets criteria of genetic material x x x Stable storage of complex info -- bases can Stable go in many orders (coding) but stay fixed once ordered ordered Replicable--one chain determines other Expressible--linear code system can work for Expressible--linear other polymers other 4. Structural variants of DNA 4. s B-DNA is standard double helix with major and B-DNA minor grooves minor s A-DNA similar but wound tighter x Unclear whether it exists in nature May appear in DNA-RNA hybrid helices May s Z -DNA has left-handed instead of righthanded twists x Small regions found near transcribing genes xMay relieve torque as helix is opened IV. RNA STRUCTURE IV. s s s A. Same as DNA except: A. Sugar is different U instead of T Stable as single-stranded molecule IV. RNA STRUCTURE IV. A. Same as DNA except: A. x Sugar is different x U instead of T x Stable as single-stranded molecule s B. Three large forms 1. mRNA -- tranmits info from DNA 2. rRNA -- translation macinery 3. tRNA -- interpreters of translation s C. Multiple small forms (more later) V. DNA and RNA Structural Variants V. A. Both can self-pair when single-stranded s 1. Hairpins Common in RNA Plain stem or stem-loop s 2. Compound stems and circles Common in RNA s V. DNA and RNA Structural Variants V. s A. Both can self-pair when single-stranded 1. Hairpins Common in RNA Plain stem or stem-loop s 2. Compound stems and circles Common in RNA s s s B. Methylation Methyl group added to base, usually C Changes how proteins interact with DNA / RNA...
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