Z - DNA: comparison with A-DNA and B-DNA

The most common form of DNA that occurs in living organisms is B-form or Watson and Crick's model of DNA. Under certain conditions, this form changes its configuration.
There are 6 different morphological forms of DNA: A, B, C, D, E and Z. Three biologically active forms of DNA are A-DNA, B-DNA, and Z-DNA.
A-DNA: this form is double-stranded, right-handed helical DNA. It is a dehydrated form that occurs in an environment richer in Na+ and less water. It shows 11 base pairs per turn of the helix and a diameter of 23 A. The height of the pitch is 28 A and axial rise is 2.56 A. The sugar-phosphate backbone is regular. The repeating units are mononucleotides. It shows the presence of 2 deep groves and 2 shallow groves.
B-DNA: occurs at low salt concentration and a high degree of hydration (i.e. normal conditions).
Z-DNA: Rich et al. working at MIT, USA studied the molecular structure of DNA fragments at atomic resolution. They proposed a Z-form of DNA along with B-DNA.
The Z-DNA shows the following characteristics:
 It is stabilized by high salt concentration.
 It is left-handed DNA.
 It is a double-helical structure with a zig-zag sugar-phosphate backbone.
 In Z-DNA, the repeating unit is a dinucleotide and the sugar residues have an alternating orientation of dinucleotide.
 In Z-DNA, 12 base pairs are present per turn.
 The height of the pitch is 45 A.
 The diameter of the helix is 18 A
For additional information about DNA and Nucleic acids, you can also refer to
• Watson and Crick's Mod... (“Watson and Crick’s model of DNA: Part-I (Characteristics)”- The video explains characteristics of DNA molecule with suitable models.)
• Nucleic Acids: Composi... ("Nucleic Acid Composition Part-I" Video describes various components of nucleic acids and gives a simple trick to draw and remember the structure of nitrogen bases, ribose and deoxyribose sugars. )
• Nucleic Acid Compositi... (‘Nucleic Acid Composition Part-II: Formation of polynucleotide and nomenclature of N, NS and NT’)
• Nucleic Acids: Made it... ("Nucleic Acids: Made it easy" )

[@swapnilombale4329]

U are amazing sir!!🙏🏻 this is so confusing topic...and u made it very easy for the students!🙏🏻 thanks a ton ,sir!🙌

[@DrSudhakarKhot]

Thank you Swapnil.

[@swapnilombale4329]

@@DrSudhakarKhot pleasure sir!🙏🏻🙏🏻

[@udaykhopade3236]

Real clg mde offline lectures hotE tva kadi pat jhale nahi. BUT Online you tube lectures attended karunch pat jhale.. SIR EK NUMBER GREAT SIR

[@DrSudhakarKhot]

Thank you Uday Sir

[@krishanuchoudhury7943]

Thank you so much read watson mol bio but was missing some concepts so can visualize with the model! Thank you very much🎉❤

[@nancyfaby160]

Wonderful explanation sir

[@sampadabachche7759]

Such briliant lecture sir DNA helical structure.I am lucky sir because I am your student sir

[@DrSudhakarKhot]

Wish you Best of Luck Sampada.

[@sampadabachche7759]

Thank you sir

[@ankitjangir05]

Such a nice explanation.. 👌
Where is various RNA forms,DNA replication and gene regulation...??? Plzz make videos on these topics,sir...

[@DrSudhakarKhot]

Thanks for your comments. Surely within next few days I will upload the videos on RNA and DNA replication.

[@ankitjangir05]

@@DrSudhakarKhot thank you sir 😊.... Waiting.

[@elleinafridi8619]

Amazing explanation ❤

[@drinnocent_bot]

Nice Idea of helical structure Sir...
It is my badluck sir that I am not your student. 😍🙏

[@DrSudhakarKhot]

Thank you for your complements.

[@dr.sachinpatil5943]

Very nice information

[@DrSudhakarKhot]

Thank you Sir. Plz keep watching and share with your students.

[@anilganta8087]

Sir please do more videos on topics like Carbohydrates,Amino acids, peptides,Proteins, Enzymes, Lipids and Nucleic acids for BSc level... please

[@DrSudhakarKhot]

Sure. 👍

[@dr.behappy1234]

Excellent explanation

[@DrSudhakarKhot]

Thank you Madam, please share it with your students.

[@Bio_Microbio_LifSci_Tut_Mentor]

Please tell in which form of DNA syn- & anti- conformation around the glycosidic bond are present?