MBB 331 Lecture Notes - Lecture 3: Ecori, Tobacco Mosaic Virus, Phosphodiester Bond
22 Jul 2020
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L = t + w (twist + writhe) Forms a: writhe and twist have a reciporical relationship. If twist goes up, writhe goes down, and vice versa. Linking number does not change unless there is an outside agent (known as topoisomerase in vivo: deltal = l l0 (linking number linking number initial) sigma = deltal/l0 (supercoiling = change in linking number/linking number initial) Linear dna: moves faster than nicked bc linear can fold on itself sometimes, making it more compact than regular loose and nicke. Poll question 3: linking number is very hard to define when there"s a nick. Its very difficult to repair if dna is broken (double stranded nick), but nicked. Dna packing in viruses: tobacco mosaic virus (tmv) is an rna virus, has an rna genome packed in a rod shaped viral coat, rna genome is super coiled inside this viral coat with an rna binding protein.
