Obj 3-Structure of DNA & its Functions


= Deoxyribonucleic Acid

= Long chain of nucleotide


Nucleotide – composed of

  1. Phosphate Group (PO4)
  2. 5C Sugar (Ribose – RNA  /  Deoxyribose – DNA)
  3. Nitrogenous Base (Purine -2 ring(AG) /  Pyrimidine-1 ring(TCU)

Basic Structure Of Nucleotide

F05-01.jpg (1024×394)

Difference between Ribose and Deoxyribose of 5C Sugar

Difference between Purine & Pyrimidine of Nitrogenous Base

Nucleoside – nucleotide without PO4

Difference between Nucleoside and Nucleotide

Primary Structure

-Double stranded Helix

-the 2 strands are anti-parallel

-always read 5′ to 3′

-polymers linked 3′ to 5′ by phosphodiester bridges

-bonds between

  • polymers (phosphate & sugar) – phosphodiester bridges
  • sugar & base – (purine =B-N9-glycosidic bond  /  pyrimidine =B-N1-glycosidic bond)
  • base & base – hydrogen bond

Phosphodiester Bond (Phosphate-Sugar)

Glycosidic Bond (Sugar-Base)

Hydrogen Bond (Base-Base)

A-T (2)  /  G-C (3)

Secondary Structure

-sugar-phosphate backbone outside

-Bases (hydrogen bonded) inside

-Base-pairing rule   { A-T (2)  /  G-C (3) }


  1. Storage information
  2. Replication
  3. Access of infomation for protein synthesis

Functions of Nucleic acids

-Carrying the genetic information through generation

Functions of Nucleotides

  1. Nucleoside 5′-triphosphates are carriers of energy, energy stores
  2. Forming a portion of several important coenzymes such as NAD+, NADP+, FAD and coenzyme A
  3. activated intermediates in numerous biosynthetic reactions, as SAM in glycoprotein synthesis
  4. Cyclic nucleotides are signal molecules (second messenger) and regulators of many aspects of cellular metabolism
  5. ATP is central to energy metabolism
  6. GTP drives protein synthesis
  7. CTP drives lipid synthesis
  8. UTP drives carbohydrate metabolism





  1. salam berkunjung lagi….bagus la ang wat semu ni…br free…klu search kt tenet…ak tgk yg kimia2…boi semu kna purchase br ble bc….ni ang kra wat 2 in 1 la no…1 tuk ang n tuk org len…bagus2…

    tp sai DNa ni la ak pling tension blajaq kt PASUM 2…x ingt ak replication n so on nya process 2…klu ang rajin ble la wat…n klu ble bg dlm bntuk yg mudah d fahami…GOOD LUCK!!

    • ingat yg ni pown free,haha…
      Just kidding…baguslah berkunjung selalu…kalu khatam suma yg aku insyallah tulis ni,jadi top scorer la ko taun dpan sem 1,haha

  2. salam. rajinnya hg study cuti2 ni. Bagus la mmg bertuah aa ada housemate pandai cam hang ni. hehe. blogspot tkleh komen eh? bagus gak ada 2 belog yg berlainan citarasa hehe. 🙂 see u soon for d next update.

    • wsalam..haha,secara jujur kalu ang x bagi tip2 yg berguna aku xleh score tahun ni…n ang pown top scorer pa,haha…. Jgn segan2 bagi tip lg taun dpan,haha…….
      Pasal blogspot,x perasan plak ter’setting xleh comment..patut pown x pernah org comment,haha..sia2 sedey org x comment

    • Chaya
    • April 16th, 2011

    Thanks so much!! Its rlly helpful to me! Im only a first year, love the pictures 😉 Im proud to see that ur Malaysian too!! 😀 (I’m not a Malaysian 😛 – just love the place!)

    Take care and good luck with the future! xox

    • hehe glad to be helpful 🙂
      how do you know i’m malaysian? 😛
      thanx for the wish ^.^

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