DNDNAAStructuStructurere

What is DNA?

What is DNA for?

DNADNA DDeoxy-ribose eoxy-ribose NNucleic ucleic AAcidcid Structure that has material that determines Structure that has material that determines

an organisms traitsan organisms traits TraitTrait: a characteristic that helps determine : a characteristic that helps determine

a unique individual (makes you YOU)a unique individual (makes you YOU) No one’s No one’s DNADNA is the same (kinda like a is the same (kinda like a

fingerprint)fingerprint)

DNA Makes You DNA Makes You YOU!YOU!

DiscoveryDiscovery Discovered by Discovered by

James WatsonJames Watson and and Francis CrickFrancis Crick

Made of two Made of two chains of chains of nucleotidesnucleotides held held together by together by nitrogenous basesnitrogenous bases

NucleotidesNucleotides Structure made of three partsStructure made of three parts

PhosphatePhosphate SugarSugar BaseBase

Nitrogenous Nitrogenous BasesBases

Four types of bases in DNAFour types of bases in DNAAdenine = AAdenine = AGuanine = GGuanine = GCytosine = CCytosine = CThymine = TThymine = T

Purines and Purines and PyrimidinesPyrimidines

Purine Pyrimidine

Two Rings

Adenine , Guanine

One Ring

Thymine , Cytosine

BondingBonding Bases bond to other bases in a very specific wayBases bond to other bases in a very specific way ADENINEADENINE will ONLY bond will ONLY bond

with with THYMINETHYMINE

CYTOSINECYTOSINE will ONLY bond will ONLY bond with with GUANINEGUANINE

Two ChainsTwo Chains- the two chains of - the two chains of

nucleotides are bound nucleotides are bound together by the basestogether by the bases

- chains bind together upside - chains bind together upside down!down!

- two chains are also spirally - two chains are also spirally around each otheraround each other

- the complete structure of - the complete structure of DNA is called DNA is called DOUBLE DOUBLE HELIXHELIX

QuestionsQuestions1) What does DNA stand for?1) What does DNA stand for?2) What three parts make up the nucleotide?2) What three parts make up the nucleotide?3) What are the four types of bases?3) What are the four types of bases?4) Which bases are Purines? Pyrimidines4) Which bases are Purines? Pyrimidines5) How would you describe the Double Helix?5) How would you describe the Double Helix?

Answer at the back of your notes Answer at the back of your notes ( WRITE THE Q’S !!! )( WRITE THE Q’S !!! )