DNApart 1

Prep by : Mohamed Abdukadir KalifMPHIL in optometry

The word DNA

• First of all the abbreviation of the word DNA is (Deoxyribonucleic Acid)

DNA

• In very basics• All the life programs are primarily stored in

DNA• For example : why cow is different from you,

because it has different DNA than you . and why banana is different than you ,

because it has different DNA than you

• Basically in a fertilized ovum , all the genetic material which is present , have the complete program to make structurally and functionally complete organism

and all that programming is in the molecule of DNA

• So u can say the master plan of life for every organism is present in DNA

RNA

• DNA expresses it self in the form of RNA • The functional copies of DNA are RNA• You can say master plan is in DNA , and the

master plan makes a functional copies which is the RNA

• And from the RNA we make proteins

So how the system works

• In particular cell , DNA will express certain RNA ‘s , and RNA will make particular type of proteins , and those proteins will determine the structure of a cell as well as the function of a cell

Definition of DNA

• DNA is un branched linear polymer of nucleotides .

• For example : in this picture , lets say these are un branched linear , polymer of nucleotides

• So as the picture is shown DNA contains nucleotides , this means to understand how the DNA is made , actually u must understand how nucleotides are made

• To make a molecule of DNA, first of all we must have a nitrogenous bases

what are nitrogenous bases ?• Nitrogenous bases are nitrogen containing

carbon rings

• there are two types of nitrogenous bases 1= double ring structure which are called

( purines ) 2= single ring structure which are called

( pyrimidines )

-purines ( double ring structure ) contains 1= Adenine 2= guanine- pyrimidines ( single ring structure ) contains 1=cytosine 2=thymine

• Nitrogenous bases alone can not make DNA , so they are fused with sugar , when sugar contains 5 carbons and oxygen , they are called (pentoses) .

• In carbon position number 2 and carbon position number 3 , if they are hydroxyls this sugar is called (ribose sugar ) .

In ribose sugar , if you remove the oxygen from carbon position number 2 and leave only

hydrogen , then this sugar is called ( dioxyribose sugar )

• If in a nucleic acid (nucleic acid is DNA and RNA) with dioxyribose sugar is used then that nucleic acid is going to be DNA

To be continued