武漢大學(xué)分子生物學(xué)全部課程3-文庫吧資料
2025-02-13 02:40本頁面
【正文】 cytosine, pair with each other. (Related to replication and transcription) DNA STRUCTURE (3) The Two Chains of the Double Helix Have Complementary Sequences Example: If sequence 5’ ATGTC3’ on one chain, the opposite chain must have the plementary sequence 3’ TACAG5’ DNA STRUCTURE (4) WatsonCrick Base Pairing (Related to replication and transcription) The strictness of the rules for “ WastonCrick” pairing derives from the plementarity both of shape and of hydrogen bonding properties between adenine and thymine and between guanine and cytosine. A:C inpatibility Hydrogen Bonding Is Important for the Specificity of Base Pairing DNA STRUCTURE (5) ? The hydrogen bonds between plementary bases contribute to the thermodynamic stability of the helix (why?) and the specificity of base pairing ? Stacking interactions between bases significantly contribute to the stability of DNA double helix The double helix has Minor and Major grooves (What Why) DNA STRUCTURE (5) (See the Structural Tutorial of this chapter for details) It is a simple consequence of the geometry of the base pair. The Major groove is rich in chemical information (What are the biological relevance?) DNA STRUCTURE (6) The edges of each base pair are exposed in the major and minor grooves, creating a pattern of hydrogen bond donors and acceptors and of van der Waals surfaces that identifies the base pair. A: Hbond acceptors D: Hbond donors H: nonpolar hydrogens M: methyl groups The double helix exists in multiple conformations. DNA STRUCTURE (7) ? The B form (10 bp/turn), which is observed at high humidity, most closely corresponds to the average struct
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