DNA+Structure+&+Replication

__Purpose of DNA__

DNA has two biological functions. It serves to store and determine biological characteristics of any living thing, and it serves the purpose of synthesis of biological molecules such as proteins and RNA molecules. It determines purposes and characteristics of living things by a careful arrangement of nitrogen base pairs.

DNA consists of two molecular strands called nucleotides. These have backbones attached made of sugars and phosphates. Attached to these is a specific base pair, which is used to code for protein. DNA also directs a process called transcription, which is the creation of a molecule called RNA (Ribonucleic acid). RNA is used for the synthesis (creation) of proteins. This picture depicts DNA well: DNA VS RNA NOT NEEDED--ONLY DNA STRUCTURE! !__DNA Structure__ DNA is structured in the shape of a double helix. If you do not know what this is, try imagining the shape of a ladder, but instead of standing straight up, it was twisted together into a coil. This is the double helix shape of DNA.

This image may help: U.S. Library of Medecine. "DNA Structure", Drawing. S//cience.howstuffworks.com.// 25 Dec 2011. 

The legs holding up the rungs of the ladder are made of a sugar-phosphate group. The rungs of the ladder are one of four base pairs, Adenine, Thymine, Guanine, and Cytosine. These pairs are specific and only match with another, Adenine only to Thymine, and Guanine only to Cytosine. The pattern and arrangement of these pairs is what codes for proteins and what makes us the way we are. This is a helpful video: media type="youtube" key="qy8dk5iS1f0" height="315" width="420"

__DNA Replication EXPLAIN THIS BETTER USIGN A PIC__ DNA replication starts with an enzyme called helicase unwinding the DNA strand. From there on, an enzyme complex called DNA polymerase goes down the strand pairing the nucleotides with their compliments. The DNA is then proofread for any mistakes in copying (But this is not always perfect, there can be mistakes left). And after the one strand is now two, the seperate strands wind up again into the double helix.

"DNA Replication". Drawing. //dnareplication.info.// 26 Dec 2011. 

Now here is one more video to sum up what was said here: media type="youtube" key="gW3qZF9cLIA" height="315" width="420"