- Created by: aaishak
- Created on: 28-02-15 17:25
DNA contains the instructions to make every single living organism.
It contains the elements C.H.O.N.P, they have 3 parts to them: the phosphate, sugar and base.
The phosphate group is negatively charged and it gives the nucleic acids its properties (Its called nucleic acis *** the DNA is a weak acid and is found in the nuclie of the cells).
The sugar is called a Pentose sugar as its a 5 carbon sugar, its other name is deoxyribose.
The nitrogenouse base has 4 elements in and they are C.H.O.N, because there are 4 bases there are also 4 nucleotides. The bases are A,T,C,G.there nucleotides sound similar.
Nucleotides polymerise by phosphodiester bonds between the carbon 3 and the oxygen in the phosphate group, its a condensation reaction. As the bases don't take part in the reaction and just extend of the sugar (which is liked to the phosphate group) they are offten called the sugar phosphate backbone.
If 2 nucleotides are joined together they were called dinucleotides, if 3 are joined together than they are called trinucleotides, while if there are lots joined together than they are called polynucleotides.
In a DNA they have 2 ends on one end its 5' and on the other its the 3' this is because on the 5' end the phosphate group is attached to the carbon 5, while on the 3' end the phosphate group is attached to carbon 3.
The bases are attached by hydrogen bonds, between the A and T base there are 2 hydrogen bases, while between the C and G based there are 3 hydrogen bonds.
structure of DNA
DNA is double-stranded meaning there are 2 polynucleotides alongside each other, they are also antiparallel so they run in opposite directions.
The structure of the DNA makes it well suited for its job of Storting and expressing genetic information.
The double-stranded helix is good for providing stability and protecting the bases
The long molecule as it can store lots of informnation
While it being coiled is good to as its compact so it stores a lot of information in a small space
Having 4 bases allows the DNA to be encoded and stored
Having hydrogen bonds allows it to be strong and stable
Being double stranded allows it to replicate semi-conservatively.
Complementary base pairing allows identical copies to be made.
Weak hydrogen bonds between basees allow an easy streams separation for replication.
2 complementary strands mean that there are 2 copies of information, which is useful for repair, copying and error checking.