Differentiate between three different types of DNA
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Answer:
Three major forms of DNA are double stranded and connected by interactions between complementary base pairs. These are terms A-form, B-form,and Z-form DNA
Different forms of DNA- A form, B form, Z form
The right-handed double-helical Watson – Crick Model for B-form DNA is the most commonly known DNA structure.
In addition to this classic structure, several other forms of DNA have been observed.
The helical structure of DNA is thus variable and depends on the sequence as well as the environment.
C-DNA
Formed at 66% relative humidity and in presence of Li+ and Mg2+ ions.
Right-handed with the axial rise of 3.32A° per base pair
33 base pairs per turn
Helical pitch 3.32A°×9.33°A=30.97A°.
Base pair rotation=38.58°.
Has a diameter of 19 A°, smaller than that of A-&B- DNA.
The tilt of base is 7.8°
D-DNA
Rare variant with 8 base pairs per helical turn
These forms of DNA found in some DNA molecules devoid of guanine.
The axial rise of 3.03A°per base pairs
The tilt of 16.7° from the axis of the helix.
E- DNA
Extended or eccentric DNA.
E-DNA has a long helical axis rise and base perpendicular to the helical axis.
Deep major groove and the shallow minor groove.
E-DNA allowed to crystallize for a period time longer, the methylated sequence forms standard A-DNA.
E-DNA is the intermediate in the crystallographic pathway from B-DNA to A-DNA.
three major types of DNA are double stranded and connected by interaction between complementary base pairs .these are terms A- form,B-form,C-form from DNA