DNA: Deoxyribonucleic Acid

What is DNA? Humans have 46 chromosomes (23 pairs) Each chromosome is made up of a tightly coiled strand of DNA

Genes Each strand of DNA has multiple sections, or genes. Each gene has the instructions to make a specific protein. There are hundreds of proteins that each have a specific function necessary for life.

Structure of DNA The structure of DNA is a double helix Each strand has a specific pattern of four nucleotide bases The four bases are adenine (A), guanine (G), cytosine (C) and thymine (T) The bases pair up on the opposite strand (A with T and G with C)

The DNA Code It is the order of the bases that provides the information needed to make proteins Every 3 bases on a DNA strand is a codon. Each codon codes for an amino acid Each protein is made up of a specific combination of amino acids

Mutations A mistake can occur when the section of DNA is copied to make a protein Any change in the order of the bases on a strand of DNA is called a mutation These changes in the code can (sometimes) cause a change to the amino acid being coded for. This can cause the protein to form incorrectly or possibly not at all.

Effects of mutations Neutral - No visible effect –or- does not impact organisms survival Harmful – results cause protein to be faulty/not function properly (can be lethal or cause serious problems) Beneficial – sometimes the change causes a variation that benefits the organism (Ex/ developing resistance to a disease)

Homework Use the following terms in a paragraph: DNA, gene, bases, amino acid, protein Model a section of DNA, then make a second model showing a mutation to the code.