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The purpose of this book is to define, describe and illustrate the structure of DNA for high school students.
image by publik15 on flickr
DNA is located in the nucleus of cells. It makes up genes, which carry genetic information from generation to generation. DNA is a string of a series of four nucleotides.
Deoxyribonucleic acid (DNA) is made up of linked nucleotides.
It is double stranded. In other words, DNA has two chains of linked nucleotides that are joined by hydrogen bonds.
image by mknowles on flickr: http://www.flickr.com/photos/mknowles/47457221/sizes/m/
Nucleotides are subunits of DNA.
Many nucleotides strung together make a DNA strand.
Click here for a 3-D view of DNA.
Structure of DNA
DNA is like a twisted ladder or double helix, with the ladder turning to the right. It is called a right hand turn.
The sides of the ladder are made up of a sugar-phosphate backbone.
The steps of the ladder are made up of two nucleotides pairing together and connecting by hydrogen bonds. This is how the two strands of DNA come together. Here is a 3-D model of DNA.
image on http://www.flickr.com/photos/eliotc/972744116/sizes/l
Complementary Base Pairing
This forms the step of the ladder in a DNA twisted ladder or double helix. Nitrogenous bases are parts of a nucleotide.
There are four nitrogenous bases found in DNA; adenine (A), thymine (T), guanine (G) and cytosine (C).
A pairs with T by two H bonds.
C pairs with G by three H bonds.
This pairing allows two strands of DNA to come together in a double helix.
Here is a short movie that describes base pairing.
by: spdorsey on flickr.
