What is this DNA you speak of?  DNA stands for deoxyribonucleic acid - Found in nucleus of eukaryotic cells - Found in cytoplasm of protists

Why should I care about DNA?  Two main functions 1.) Stores the genetic information of an organism.

Why should I care about DNA?  Two main functions 2.) Contains instructions for how to construct important biological molecules. Example: Building new cells

What is the structure of DNA?  Twisted ladder-like shape called a double helix Three main components 1.) Phosphate group 2.) 5 carbon sugar 3.) Nitrogenous base

What is the structure of DNA? Three main components 1.) Phosphate group 2.) Five carbon sugar 3.) Nitrogenous base – Four types - Adenine - Guanine - Cytosine - Thymine DNA ‘backbone’ “Purines” “Pyrimidines”

Nitrogenous Bases 1.) Purines - Adenine- Guanine 2.) Pyrimidines - Cytosine- Thymine The sequence of the nitrogenous bases in DNA determines the genetic code!

Nitrogenous Bases  Base Pairing - Purines ALWAYS bond with pyrimidines! pyrimidines! Chargaff’s Rules: - Adenine ALWAYS bonds with thymine A---T - Cytosine ALWAYS bonds with guanine C---G The amount of A = amount of T The amount of C = amount of G

What is the structure of DNA?

 A single strand of DNA has a 5’ and 3’ end. 3’ end: Terminates with an exposed –OH group on deoxyribose sugar 5’ end: Terminates with an exposed phosphate group

What is the structure of DNA?  Antiparallel strands - Single strands of DNA run opposite to one another in the double-helix.

What is the structure of DNA?  Antiparallel strands - Sequence of nucleotides is typically written in the 5’ to 3’ direction.5’-ACTG-3’ Which is NOT the same as: 5’-GTCA-3’

Can you build your own DNA model?