this is my own understanding , if i make any mistakes please feel free to contact me email: xanaf05@hotmail.com

1. DNA
part 1
Prep by : Mohamed Abdukadir Kalif
MPHIL in optometry

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

4. 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

5. • 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

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

7. 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

8. 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

10. 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

11. • 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

12. • 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

13. • there are two types of nitrogenous bases
1= double ring structure which are called
( purines )
2= single ring structure which are called
( pyrimidines )

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

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

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

20. In ribose sugar , if you remove the oxygen from
carbon position number 2 and leave only
hydrogen , then this sugar is called
( dioxyribose sugar )

22. • 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

23. To be continued