DNA Introduction

Background Body consists of 60 trillion cells –Most of these cells contain a nucleus Not mature red blood cells –Each nucleus contains the genetic material in chromosomes –Genes are found on chromosomes nucleu s

Chromosome → Gene → DNA

Background The gene is the fundamental unit of heredity –Holds instruction for the body cells to make proteins that determine everything from hair color to our susceptibility to disease Each gene is composed of a specific sequence of DNA

DNA DNA stands for deoxyribonucleic acid –Blueprint, or directions, for all living things Remains even after the cell is dead (have found dino-DNA)

Dinosaur DNA? They probably aren't in your family tree, but for those of you interested in DNA science....Soft tissue found in the thigh bone of a nearly 70-million-year- old Tyrannosaurus rex recently discovered in Montana raises hope of potentially extracting DNA to learn more about the evolution and lives of dinosaurs. Preliminary testing on intact blood vessels showed them to be virtually indistinguishable from those recovered from ostrich bones. Jurassic Park may not be such a big stretch after all.

Tyrannosaurus rex bone fragments show vascular canals (A) and transparent vessels (B). The transparent vessels from the Tyrannosaurus (C) are very similar to those from an ostrich (D), a bird that many paleontologists think are living descendants of some dinosaurs. Higher magnification shows a branching pattern in the Tyrannosaurus vessels (E) and microstructures consistent with those in the ostrich vessels (F).

DNA components DNA is made up of primary units called nucleotides –Each nucleotide is composed of three pieces Sugar (deoxyribose) Phosphate group Nitrogenous base

Nitrogenous bases Four different bases –Adenine –Guanine –Thymine –Cytosine Universal in all living things Order of bases determines the trait that a person will have

AdenineGuanine CytosineThymine Phosphate group Deoxyribose DNA Nucleotides Section 12-1

DNA shape DNA is in the form of a double helix, or spiral ladder –The sugar and the phosphate group create the backbone of the molecule –The bases are the rungs of the ladder

Hydrogen bonds Nucleotide Sugar-phosphate backbone Key Adenine (A) Thymine (T) Cytosine (C) Guanine (G) Structure of DNA Section 12-1

Base pairing rule Each base matches up with one other specific base = base pairing rules –Adenine will always bind to thymine, and vice versa –Cytosine will always bind to guanine, and vice versa Each DNA strand contains over 1 million base pairs

Website NOVA online: Journey into DNA