In one case in a life time, everyone must have heard the term Deoxyribonucleic acid. Now y'all tin recollect that later because nosotros are going to larn here something more nearly DNA.

DNA is genetic cloth. Chromosomes are made upward of Deoxyribonucleic acid. In Human prison cell, 46 chromosomes (23 Pairs) are present. A small segment of DNA over chromosome is known as gene. Factor is ultimately storing all genetic data. It carries all data for formation of any kind of protein. You know this right? Here! All we are going to learn well-nigh is structure of DNA.

A detailed study of construction of Dna was explained by Watson & crick. They got Noble Prize (1962) for explaining this too.  Term DNA was given by Zaccharis.

Dna is a polymer. Its monomeric unit is known as nucleotide.  Before learning nigh a big molecule Deoxyribonucleic acid, permit me tell you almost construction of nucleotide.

Nucleotide if further made up of three things viz. Phosphate grouping, ribose sugar & nitrogenous group (Fig A).

SD-1 SD-2 Phosphate Group – It is attached to 5’ C of Carbohydrate molecule (Fig A). There can be mono, di or tri phosphate.

Ribose Sugar – It’s basically a ring of 5 carbons. RNA consists of ribose saccharide while Deoxyribonucleic acid consists of deoxyribose sugar (Fig B).

Nitrogenous bases – Nitrogenous bases are of ii types viz. Purines & Pyrimidines (Fig C). Dna consists of A, T, C & M as its bases. While RNA consists of A, U, C & G. Let me tell yous their full form besides 🙂

SD-3A – Adenine

T – Thymine

C – Cytosine

G – Guanine

U – Uracil

DNA is basically a chain of nucleotides known every bit Polynucleotides. One nucleotide is attached to another past making phosphodiester bond. I h2o molecule is as well released in this process (Fig D). 3’C of one sugar molecule make bonds with Phosphate group fastened to the 5’C of another sugar. That’southward why we phone call it equally 5’ -3’ Phosphodiester bond.

SD-4One polynucleotide chain is bonded with another chain to form the double stranded molecule. Energy required for formation of DNA is fulfilled past itself. No external source is required. A number of nucleotides (dATP, dGTP, dCTP, dTTP) are present which give the energy.

1 strand of DNA moves in 5’ to 3’ direction while some other strand of DNA moves in 3’ to 5’ direction. That’s why we say that DNA is double stranded molecule which consists of antiparallel strands. In between the two strands, Nitrogenous base of i nucleotide in one strand makes bond with another nitrogenous base of other strand.

SD-5

A is bonded to T by two Hydrogen bonds (A=T) While C is bonded to One thousand by 3 Hydrogen bonds (C≡1000). This base pairing is known as complimentary base of operations pairing. Sugar & Phosphate groups are present in the strand itself & that why they form the backbone of DNA.

Presence of Hydrogen bonds & Phosphodiester bonds makes DNA a strong molecule.

Let me tell yous some more than features of Deoxyribonucleic acid every bit explained past Watson & crick.

  1. DNA is a three dimensional structure with two mutually twisted strands. Deoxyribonucleic acid is right handed helix.
  2. Diameter of Dna is 20nm (20A0). Distance between adjacent base pair is .34nm (3.4A0).
  3. 1 consummate turn of Helix is iii.4nm (34A0).
  4. Dna consists of Major (deep) groove & minor (shallow) groove.
  5. Along a polynucleotide chain, base sequence is variable. Genetic information is carried by specific base sequence.
  6. Dna consists of two things cadre + Backbones. Core is made upwards of nitrogenous bases (Purine & Pyrimidines) while backbone is made up of sugar & phosphate.

What decides the base compositions of DNA?

Erwin Chargaff (1950) explains certain rules about this composition. Let’due south study virtually that likewise.

  1. Corporeality of ane base (Purines) is always equals to another base (Pyrimidines). A=T & C=Grand.
  2. Relative amount of nitrogenous bases varies from ane species to another species simply it is fixed in 1 species.
  3. Sum of Purines = Sum of Pyrimidines (A+C = Thousand+T)
  4. A+T = Constant for a species (Range .iv -one.ix). C+1000

Information near DNA is even so left. Yes! You tin can dive into this link for learning.

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