DNA: Structure

DNA Structure and Purpose In simplest terms, DNA is a blueprint for life. It is made up of genes which hold the information for making proteins within the cell –Proteins in turn help make up everything in your body! DNA is a very long polymer made up of monomers called nucleotides The basic 3D shape of DNA is called the double helix The double helix looks like a twisted ladder or zipper.

DNA’s Structure CG A T

Sugar-phosphate backbone Nucleotide Hydrogen bonds The nitrogen bases are connected by Hydrogen bonds The backbone (sides) are connected by Covalent bonds. Covalent bonds How is DNA held together??

1 monomer!!! Aka nucleotide Phosphate Nitrogen base Deoxyribose 8 monomers making a small section of DNA Sides of DNA are always made up of a Phosphate and 5 carbon sugar (deoxyribose). Middle or rungs of DNA are always made up of 4 different nitrogen base pairs. Hydrogen bonds Covalent bonds

Nitrogenous Bases 2. PURINE –2 rings –Adenine (A) –Guanine (G) **Remember: “PUGA2” 1. PYRIMIDINE –1 ring –Pyrimidines have “y” **Remember: *Cytosine (C) *ThYmine (T)

Nitrogen Base pairing One pyrimidine and one purine will ALWAYS pair up. A pairs with T G pairs with C

Location and Form of DNA Prokaryotic DNA is located in the cytoplasm, usually in a circular form Eukaryotic DNA is located inside the nucleus in the form of chromosomes

How does all that DNA fit into the nucleus? Hopefully you remember this picture from cell division!

Review!!! What does A pair with? What does C pair with? What makes up the sides of a the DNA strand? What are the base pairs held together by? What consists of a phosphate group, 5- carbon sugar and a nitrogen base?