MODERN GENETICS DNA

DNA Deoxyribonucleic acid is the genetic material that is passed from one generation to the next The genetic instructions (genes) that are passed on are in the form of a chemical code contained in the DNA of all organisms

DNA DNA controls cellular activity by influencing the production of proteins Review: What is a protein? Long chains of amino acids

The sequence of amino acids in a protein determines the shape of the molecule The shape of a protein enables it to carry out specific functions for the cell (Think enzymes and lock and key!)

Proteins Proteins make up many structures and chemicals in living things: Enzymes Cell membrane Antibodies

Hormones Pigments that make eye and skin color ETC ETC ETC

DNA STRUCTURE DNA is a very large molecule (polymer) that is made up of smaller units called nucleotides

Each nucleotide consists of: A phosphate group

Deoxyribose which is a 5 carbon sugar

Nitrogen bases , which are Adenine Thymine Guanine Cytosine

A Nucleotide

Watson and Crick model of DNA DNA is organized like a ladder The sides of the ladder are composed of alternating phosphate and sugar The rungs of the ladder are composed of nitrogen bases that are held together by weak hydrogen bonds The ladder is twisted to form a double helix

Base pairing Nitrogen bases combine in a certain order

Adenine only pairs with Thymine AT or TA

Guanine only pairs with Cytosine CG or GC

DNA Replication DNA makes exact copies of itself DNA unzips along the weak hydrogen bonds between each base pair Free nucleotides in the cytoplasm join with the proper base and 2 identical DNA molecules form This occurs during mitosis and meiosis

http://www. lewport. wnyric http://www.lewport.wnyric.org/jwanamaker/animations/DNA%20Replication%20-%20long%20.html DNA Replication - long.htm