Saturday, November 17, 2007

Nucleic Acids

Hey guys. I know today was the happiest day for everyone because today we finally finished biochemistry. We are finally over with chemistry!!!!!!!!!!!!!!!!!!!!!!!!

Today we finished off biochemistry with Nucleic acids. Nucleic acids are the information storage devices of our cells. Not only do nucleic acids store information but they also transmit hereditary information to the next generations. Nucleic acids are able to serve as templates to produce precise copies of themselves, so that the information that specifies what an organism is can be copied and passed down to its descendants. The information that is being passed on between generations of organisms is the ability to produce the correct proteins. There are two varieties of nucleic acids that aid in the process passing on this information to the next generation: DNA and RNA. The DNA encodes the information that is used to assemble proteins while the cells use RNA to read the cell's DNA encoded information and direct the synthesis of proteins. The RNA then passes out into the rest of the cell, where it serves as a blueprint specifying a protein's amino acid sequence.

Nucleic acids are made out of monomers which are called nucleotides. There are three parts to nucleotides: a nitrogen base (C-N ring), pentose sugar (5C), and a phosphate group. The pentose sugar is different in both DNA and RNA in that RNA has ribose while DNA has deoxyribose which means without sugar. Now the phosphate group is highly electronegative because it has oxygen and is a charged particle. So nucleic acids are highly charged molecules making them hydrophilic and not fearing water. Now there are two types of nucleotides: purines and pyrimidines. Purines are large, double ring molecules found in both DNA and RNA. Purines are adenine and guanine. Pyrimidines are smaller, single-ring molecules and they are cytosine, thymine, and uracil.

Before we go on to the building of the polymer, we should talk a little about DNA and RNA. DNA is a double nucleotide chain in that the N bases bond in pairs across chains. The double chains in DNA wind around each other and create a double helix. RNA on the other hand is a single nucleotide chain in where the nitrogen base dangle offs and is not connected to another nitrogen base. DNA and RNA both contain adenine, guanine, and cytosine but DNA has thymine while RNA has uracil.

Now we should talk about the nucleic polymer. The backbone of the nucleic acids contains a sugar to phosphate bond. When new bases are added to the sugar of the previous bases, a phosphodiester bond forms between them. To made the bond we need the enzyme called DNA or RNA polymerase. The nitrogen bases hangs off the sugar-phosphate backbone and this is important because this allows us to make compliments from the nitrogen base that is exposed; allows us to have a template. Nucleotides bond between the DNA strands in specific pairings. A purine bonds with a pyrimidine and a hydrogen bond forms between them. Now there is a specific pairing in that adenine bonds to thymine in DNA or adenine bonds to uracil in RNA, and guanine bonds to cytosine. A 2 hydrogen bonds forms between adenine and thymine and a 3 hydrogen bond forms between guanine and cytosine. The hydrogen bonds between the nucleotides join the 2 strands together. Ratio of A-T::G-C affects the stability of the DNA molecule like in higher temperature there are more G-C than A-T because G-C contains and 3 hydrogen bond which is stronger than 2 bonds.

Well we are finally finished with biochemistry but we are not finished with sherpa reports and our next sherpa is Sarah.

"I did my homework and became who I am today because I did my homework." (yea right)

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