A branch of biology that deals with the heredity and variation of organisms. It studies how living things receive common traits from previous generations.

Comparison of different helical parameters of A, B, and Z – DNA

A – DNA Much wider and flatter. Right handed helix. major grooves: Narrow and deep minor grooves: wide and shallow Glycosidic bonds – anti-form 11 base pair B – DNA Solid central core. Right handed Major groove: wide and narrow Minor groove: narrow and deep Glycosidic bond – anti-form 10 base pair Z – DNA …

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Triple stranded DNA

Structure formed in nucleic acids by sequences that are rich in Guanine. Backbone represent by tube. Likewise, Cytosine can form C-G-C. They are less stable than double helixes due to fact that the 3 negatively charged backbone strands in triple helix results in increased electrostatic repulsion.

Chargaff’s rule

1905-2002 By Erwin chargaff It states that in all DNA, Pyrimidines and Purines must have 1:1 Adenine : Thymine Cytosine : Guanine i.e., the amount of adenine = amount of thymine similarly, the amount of cytosine = amount of guanine. It indicated that DNA is symmetrical.                (A) Double bond (T)    and   (C) triple bond (G)