Explain DNA structure briefly

• The structure of DNA (Deoxyribonucleic acid) is known as the Double Helix, as the two strands of DNA are coiled together to form a double helix.

Full form of DNA is Deoxyribo Nucleic Acid.

It is a genetic material, capable of self-replication and contains the genetic information for the development and functioning of all known living organisms.

Double helix structure of DNA:

A dinucleotide of DNA is formed by covalently linking the 5′-phosphate group of one nucleotide to the 3′-hydroxyl group of another to form a phosphodiester bond. One end of a nucleic acid strand has a 5′-hydroxyl group and the other end has a 3′-hydroxyl group. The nucleic acid chain therefore has directionality.

• DNA is made of two polynucleotide chains. Sugar and phosphate forms the backbone and bases projected to inside. DNA is usually a double-helix and has two strands running in opposite directions except viral DNA which has single strand.
• Adenine of one strand pairs with Thymine of another strand by two hydrogen bonds and vice versa. (A=T or T=A). Guanine of one strand pairs with Cytosine of another strand by three hydrogen bonds and vice versa. G = C or C = G
• A purine comes opposite to a pyrimidine. This generates approximately uniform distance between the two strands of the helix. The two chains are coiled in a right – handed fashion.
• The pitch of the helix is 3.4 nm or 34 A^{0 .} There are roughly 10 bp in turn. The distance between the bp in a helix is 0.34nm or 3.4 A⁰.
• H-bond confers stability of the helical structure of the DNA.
• Each strand has a backbone made up of deoxyribose sugar molecules linked together by phosphate groups. The 3' C of a sugar molecule is connected through a phosphate group to the 5' C of the next sugar. This is known as 3'-5' phosphodiester linkage. All DNA strands are read from the 5' to the 3' end where the 5' end terminates in a phosphate group and the 3' end terminates in a sugar molecule.

More to know:

Paternal & Maternal DNA

• Portions of human DNA that are passed from Father to child relatively unchanged through many generations are known as paternal DNA.
• Portions of human DNA that are passed from Mother to child relatively unchanged through many generations are known as maternal DNA.

There are two major types of DNA

1. Genomic DNA - This comprises the genome of an organism. The genomic DNA controls expression of the various traits in an organism.
2. Mitochondrial DNA - The DNA located in Mitochondria is called Mitochondrial DNA.

• The nucleus of a cell typically holds DNA, proteins, RNA, and other important chemicals! The DNA is negatively charged because of the presence of negatively charged phosphate group.
• Most of the proteins are negatively charged but the proteins like histones contain positively charged amino acid residues lysine and arginine which makes them positively charged that makes the balance in nucleus.
• DNA by itself doesn't have a pH. A solution of DNA would have a pH depending on the amount of DNA in the solution. If DNA has Low pH indicates that the solution DNA is in is acidic.