Sunday, November 18, 2007

Nucleic Acids

A Nucleic acids function is to store & transmit hereditary information. Examples of Nucleic Acids are RNA (ribonucleic acid) and DNA (deoxyribonucleic acid). Nucleic Acids are made out of monomers. There are long chains of monomers that you can add repeating units to. These Monomers are Nucleotides. A nucleotide consists of three parts. A nitrogen base (C-N ring) a pentose sugar (ribose in RND deoxyribose in DNA). The deoxy in deoxyribose means the sugar is missing a oxygen. The third part is a phosphate group.
RNA is a single nucleotide chain in a single helix. DNA is a double nucleotide chain consisting of Nitrogen bases bond in pairs across the chains. DNA is spiraled in a double helix. This was first proposed in 1953 by James Watson and Francis Crick.
Types of Nucleotides
THere are two types of nucleotides. THis is because of different nitrogen bases. There are purines which have bigger bases and pyrimidines which have smaller bases. Purines have a double ring nitrogen base. They consist of adenin (A) and Guanine (G).
Pyrimidines have a single ring Nitrogen Base. They conisist of cytosine(C), thymine (T) and uracil (U).

Nucleic Polymers
Nucleic polymers are the backbone of DNA. They are made of sugars and PO4. THE polymers conisist of phosphodiester bonds. These bonds are new bases added to teh sugar of a previous base. The polymer grows in one direction. Nitrogen bases hang out the sugar-phosphate backbone.

Pairing of Nucleotides
Nucleotides bond between DNA strands. These bonds are Hydrogen bonds. They are purines H bonded to pyrimidines. A::T (2 hydrogen bonds) and G::C (3 hydrogen bonds). These matchign bases are important for replication. THis way a T is always bonded to a A and vis versa. The same is with G and C. SInce the bonds are to the same purine or pyramidine there is no confusion when replicating. This way exact copies are made.

Information Polymers
They are a series of bases encoding information. An example would be words ina book. The Stored information is passed from the parent to the child. Because of thisDNA needs to be copied accurately. The information copied is your genes. This is important because if you the parent survived then your offspring have a greater chance of survivng with your genes.

DNA Molecule
The Dna Molecule is a double helix. The hydrogen bonds between the 2 bases join the strands. A::T C::G These bonds are important becaus ethey are easy to break and put back together for replication. Copying DNA is caklled replication. The 2 strands of DNA helixs are complementary. With one strand you can build the other and with one strand you can rebuild the whole molecule. A cell copies DNA during cell reproduction (mitosis) and gamete production (meiosis).

Well thats nucleic acids. The next shurpa will be jesse. Enjoy!

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