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Types of DNA
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Dr Praveen Kumar Agrawal is teaching live on Unacademy Plus

Dr Praveen Kumar Agrawal
Ex - Faculty, Allen Kota, 22 Yrs Experience. Author - 17 books Known for best explanation Youtube : biology by pkagrawal

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Sir thanx for making learning easier.... & Sir do we need to read the first 4 chapters from modern history of India by spectrum since not even a single question is asked from those chapters in the previous year papers .. pls suggest
sr upload enzyme immediately.
  1. COURSE BIOMOLECULES Lesson DNA and its various types Dr. Praveen Kumar Agrawal


  2. end Double helical structure and specification 3 end HO The structure given by Watson and Crick is of B DNA B-DNA is an alpha helix, meaning that it has a right handed . or clockwise, spiral. . There are 10 base pairs (bp) per 360-degree rotation of 2 nm3.4 nm the helix. . So each base pair is twisted 36 degrees relative to the adjacent bases. The base pairs are 0.34 nanometer (nm) apart 0.34 .So each complete rotation of the molecule T A encompasses 3.4 nm. This length is called pitch of the DNA The diameter of the helix is 2 nm, and the bases are perpendicular to the long axis of the DNA molecule. 3 end 5' end


  3. A and Z DNA A-DNA Another secondary structure that DNA can assume is . the A-DNA structure. .It exists if less water is present. Like B-DNA, A-DNA is an alpha (right-handed) helix. . It is shorter and wider than B-DNA. . Its bases are tilted away from the main axis of the molecule. Z-DNA This form of DNA occurs if DNA is placed in high salt concetration. . It forms a left-handed zigzag helix. It is left handedly coiled.


  4. 28A (a) A form (b) B form (c) Z form


  5. dfgd dfg Very Rare Right handedly coiling Parameters B DNA Rare (under high salinity) Left handedly coiling Occurrence Very common Coiling Right handedly coiling (Alpha helix) 10 (Alpha helix) Number of base pairs per turn Diameter 12 2 nm 2.6 nm 1.8 nm Pitch length 3.4 nm 2.86 nm 4.4 nm


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