 A very large molecule, found in the chromosomes of all cells  Carries the genetic code - all the instructions for the structure and functioning of the cell (and the whole organism)

 A long complex molecule in the shape of a double helix (twisted ladder)  Made of two strands of smaller molecules called nucleotides

 Each nucleotide has 3 parts: sugar, phosphate, and a nitrogenous base  There are 4 different nitrogenous bases: adenine (A), guanine(G), thymine (T) and cytosine (C)

 Phosphate and sugar form the sides of the ladder  Pairs of bases form the rungs of the ladder  A always pairs with T C always pairs with G

 A,T,C,and G form 3 letter codes called “codons”  Each 3 letter word codes for one amino acid  Amino acids are the building blocks of proteins  So, DNA has instructions for building all the proteins a cell needs

 Each strand of DNA contains many genes  A gene contains many nucleotides  Each gene carries the code for one protein

 DNA can make exact copies of itself  This is necessary so that all new cells get all the information they need  DNA replication happens in the nucleus  The molecule unzips, and new nucleotides are attached making 2 identical molecules

 DNA can’t leave the nucleus, so copies of its code are made  RNA is the messenger molecule that carries the code from the nucleus to the cytoplasm  RNA is a single strand and contains only one gene  RNA bases are AUCG

 A ribosome attaches to a strand of messenger RNA  The ribosome reads the code 3 nucleotides at a time  Amino acids are attached in the correct order to assemble the protein

Proteins have many important functions in the body. Some examples:  Enzymes to control chemical reactions in cells  Hormones to carry messages through the body  Structural proteins that make up body parts  Blood proteins like hemoglobin and antibodies