H-DNA

Today I would be writing about a very unusual form of DNA, that is, H-DNA.
The H-DNA is a triple helix. This particularly unusual form of DNA is found in vitro or possibly during recombination and DNA repair. It forms by pairing and interwinding of 3 strands of DNA. Two of the three strands contain pyrimidines [...]

Read Full Post »

Z-DNA

Z-DNA was discovered in vitro under high salt conditions. It is know to exist in the interband regions of the giant salivary gland chromosomes of Drosophila and in the transcriptionally active macronucleus of the ciliated protozoan Stylonchia mytilus. The properties of Z-form DNA are listed below:
1) It is a left-handed helix and the helical diameter [...]

Read Full Post »

A-form DNA

The A-DNA is favoured in many solutions that are relatively of water. The properties of A-DNA are:
1) Right-handed helix
2) Helix rise per base pair is 0.23 nm
3) The number of base pairs per helical turn is 11.
4) A-form DNA is shorter and has a greater helical diameter than the B-DNA. The helical diameter of A-DNA [...]

Read Full Post »

DNA forms: A, B, Z, H

One of the properties of the DNA is that it shows confirmational flexibility, and could exist in alternative structural forms. The Watson-Crick structure is the B-form DNA, or B-DNA. The B from is the most stable structure for a random sequence DNA molecule under physiological conditions and is therefore “the standard point of reference in [...]

Read Full Post »

DNA structure

The double helical model of DNA structure was given by Watson and Crick.
DNA molecule is helical with two periodicities along its long axis, a primary one of 0.34 nm and a secondary one of 3.4 nm. The most predominant form of DNA present in the cell is B-form. It is a right-handed double helix and [...]

Read Full Post »

DNA: Its properties

Some of the properties of the DNA are listed below:
1) Double helical
2) Acidic in nature
3) Shows antiparallelity
4) Shows confirmational flexibility (alternative structures) and bending
5) Binds with basic histone proteins
6) Absorbs UV light at 260 nm (heterocyclic rings of nucleotides absorb in the UV region)
7) Undergoes reversible strand separation; many DNA molecules are circular; local unwinding [...]

Read Full Post »

Deoxyribonucleic Acid: DNA

To qualify as the genetic material, DNA has to fulfil two key requirements:
1) Genotype function or Replication: The genetic material must have the capability to store genetic information, and transmit this information faithfully from parents to offspring, generation after generation. This indicates that the genetic material should have the ability to replicate itself and make [...]

Read Full Post »

Nucleic acids: DNA vs RNA

I know this is very elementary and any high school student must be knowing the differences between RNA and DNA. But I feel a blog which deals with diverse aspects of molecular biology and biotechnology deserves a mention of basic differences between the two molecules.
DNA is double helical; RNA is single helical.
DNA contains deoxyribose pentose [...]

Read Full Post »

Nucleic Acids: An introduction contd…

The base of a nucleotide is joined covalently in an N-β-glycosyl bond to the 1′ carbon of the pentose sugar, and the phosphate is esterified to 5′ carbon. The N-β-glycosyl bond is formed by removal of water, as in O-glycosidic bond formation. The nitrogenous bases present in nucleic acids are:
1) Purines: Adenine and [...]

Read Full Post »

Nucleic Acids: An introduction

Nucleic acids (DNA and RNA) are the polymers of nucleotides. Each nucleotide is made up of 3 components: 1) a pentose sugar, 2) a phosphate, and 3) a nitrogenous (nitrogen-containing) base. A nucleotide without the phosphate group is called a nucleoside. The nitrogenous bases are derivatives of two compounds: pyrimidine and purine. The bases and [...]

Read Full Post »