What is special about the DNA Form B?

What is special about the DNA Form B?

B-form DNA is a right-handed double helix, which was discovered by Watson and Crick based on the X-ray diffraction patterns. It is the common form of DNA exists under normal physiological condition. The double strands of B-DNA run in opposite directions.

What are the main structural features of B-DNA?

What are the main structural features of B DNA? Bases are aligned perpendicular to the central axis of the molecule. 10 base pairs per turn. Consider a piece of double stranded DNA in which each strand of the helix has 1800 nucleotides.

What are 5 characteristics of DNA?

DNA contains four basic building blocks or ‘bases?’: adenine? (A), cytosine? (C), guanine? (G) and thymine? (T). The order, or sequence, of these bases form the instructions in the genome. DNA is a two-stranded molecule. DNA has a unique ‘double helix’ shape, like a twisted ladder.

What are the characteristics of DNA?

In essence, DNA stores information in the form of code in four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T). The DNA base pairs with each other A with T, C with G, forming base units. These genes are passed down from parents to offspring and carry with them some specific individual traits.

Why is B form DNA most stable?

It is known that the stability of the double helical structure of B-DNA is supplied by the hydrogen bonds as proposed by Watson and Crick3 and by the stacking interactions.

What are the main differences between A and B forms of DNA?

In B-form, the base-pairs are almost centered over the helical axis (Figure 2.5. 4), but in A-form, they are displaced away from the central axis and closer to the major groove. The result is a ribbon-like helix with a more open cylindrical core in A-form.

What is the difference between A and B DNA?

A-DNA is a double stranded helical structure almost similar to B-DNA but with a shorter and more compact structural organization. Ø A DNA is 20 to 25% shorter than B-DNA due to the smaller rise per turn. Ø A-DNA contains 11.6 base pairs per turn. Ø The distance between the adjacent base pairs is 2.9 Å.

What are the 3 main features of DNA?

The basic units of DNA are nucleotides. These nucleotides consist of a deoxyribose sugar, phosphate and base.

What are the 2 characteristics DNA must have?

Describe two characteristics that DNA needs to fulfill its role as a genetic material. DNA must code for a protein and be able to replicate. remnant of a structure that may have had an important function in a species’ ancestors, but has no clear function in the modern species.

What are the characteristics of DNA that make mitosis possible?

DNA can replicate itself because of the way its double strands relate to one another. The purines and pyrimidines that join the two strands pair exclusively with only one other base. This ensures that when the DNA strands separate to replicate an exact copy is created.

How does DNA determine the characteristics of an organism?

DNA contains the information to make proteins, which carry out all the functions and characteristics of living organisms. DNA carries all of the information for your physical characteristics, which are essentially determined by proteins. So, DNA contains the instructions for making a protein.

Is B-DNA dehydrated?

Several reports have shown that B-DNA succumbs to A-form upon dehydration down to a water activity (aw) of 81% r.h. (11,12). Further dehydration can even lead to denaturation of natural DNA. Reports have also suggested that dehydrated DNA is more sensitive to damage by high temperature and UV radiation (9).

What is the difference between DNA a and DNA B?

It is a right-handed double helix fairly similar to the more common B-DNA form, but with a shorter, more compact helical structure whose base pairs are not perpendicular to the helix-axis as in B-DNA. It was discovered by Rosalind Franklin, who also named the A and B forms.

What is the diameter of a B-DNA strand?

The diameter of the B-DNA is ~20 Angstroms, and the distance between base pairs is ~3.4 Angstroms. The base pairing of opposite strands is stereochemically selective, Adenine always pairing with Thymine , and Guanine with Cytosine . Two and three hydrogen bonds are formed in A – T and G – C base pairs, respectively.

What is the difference between major and minor grooves in B-DNA?

Although the grooves are of similar depth in B-DNA, the major groove is considerably wider than the minor groove. The edges of the base pairs present a more complex sterochemical environment in the major groove than in the minor groove.

What do the A – B – and Z-DNA conformations mean?

Side and top view of A-, B-, and Z-DNA conformations. Yellow dots represent the location of the helical axis of A-, B-, and Z-DNA with respect to a Guanine-Cytosine base pair. Dehydration of DNA drives it into the A form, and this apparently protects DNA under conditions such as the extreme desiccation of bacteria.