The Structure of DNA

The molecule of life

DNA is a Molecule

Held together with covalent bonds ** Hydrogen Bonds** hold the bases together

(Adenine, Guanine, Cytosine, Thymine)

http://www.envirohealthtech.com/images/DNA.jpg

The Double Helix

http://eur.news1.yimg.com/eur.yimg.com/xp/afpji/20060513/060513030238.z1molysc0_human-dna-double-helix-b.jpg

Ladder-like Structure

The base pairs form the “rungs” The phosphate and deoxyribose sugar form

the uprights

http://academy.d20.co.edu/kadets/lundberg/images/dna.gif

The Sugar Phosphate Backbone

http://www-math.mit.edu/~lippert/18.417/lectures/01_Intro/Pictures/10000000000001B00000023B34B57A9B.jpg

H

O

HHH H

OH

CH2

OH

HO

O

OP

Nucleotide

Phosphate group

Deoxyribose – pentose sugar (5 carbons)

Base (adenine, guanine, thymine, or cytosine)

The basic unit of the DNA molecule

Polynucleotide

A string of nucleotides The order of the bases

determines the genetic code of the organism

The molecule ‘unzips’ and free nucleotides attach to their base-pair partners to form two new double helices

DNA Replication

http://courses.cm.utexas.edu/jrobertus/ch339k/overheads-2/ch10_DNA-rep.jpg

Base PairsA - T

G - C

Semi-conservative Replication

New “daughter” DNA molecules are made up of one strand from the original “parental” DNA molecule and one newly formed strand.

http://nobelprize.org/educational_games/medicine/dna/b/replication/replication_schem.html

The chromosome unwinds

(Chromosomes are tightly packed strands of DNA)

The Process of Replication

http://www.microbeworld.org/news/articles/human_genes.aspx

The hydrogen bonds between the base pairs are broken

The Process of Replication

http://www.ba-education.demon.co.uk/gifs/replication.jpg

The Process of Replication

The two polynucleotide strands separate

http://en.wikipedia.org/wiki/Double_helix

The Process of Replication

Free nucleotides attach to the template made by the parent strands.

And Voilà!! Two identical DNA molecules.

http://www.chemsoc.org/ExemplarChem/entries/2003/imperial_Burgoine/replication.jpg