DNA part 1.

What do we know about DNA? We know that DNA evidence is used to help convict criminals, prove who the father is on Jerry Springer and in other trashy daytime TV shows but not many of us really know how DNA works, what its structure is or what it actually does....


To be simplistic about it, DNA is short for Deoxyribonucleic acid. It is the genetic material that specifies protein synthesis in cells. It holds our genes and therefore dictates every part of us.




Before I describe the structure of DNA, I want to clarify what a nucleotide is, since DNA is made up of nucleotides. If you were wearing a necklace of beads, the necklace as a whole would be DNA and a nucleotide is the bead as a singular part of the necklace.

A nucleotide is made from a phosphate (an acid), a pentose (5 carbon) sugar (Deoxyribose sugar) and a nitrogenous base.  The nitrogenous base can take up hydrogen atoms (hence the term 'base')

 Nulcleic acid is synthesized (made) by condensation synthesis.


Structure of DNA

DNA is a polymer of nucleotides all bonded together in a string and fused in the middle to a second string of nucleotides. All these nucleotides are bound together in the middle of the double helix with hydrogen bonding holding the bases together.

DNA looks like a twisted ladder- otherwise known as the double helix. The sides of the ladder are made of sugar-phosphate-sugar-phosphate.

DNA has 2 strands of polynucleotides bound together with hydrogen bonding. They twist around each other in a double helix structure.

The nitrogenous bases in DNA are paired together in complementary pairs.
There are four bases, divided into two categories.

There are the purines: Adenine (A) and Guanine (G)
There are the pyrimidines: Thymine (T) and Cytosine (C) 

Each base has a complimentary pairing with one other base:
Adenine pairs with Thymine.
Guanine pairs with Cytosine.

The bases are bound together with hydrogen bonding.