User:George Kahwai W/HOW DNA STRUCTURE COMPLIMENTS ITS FUNCTION

HOW DNA STRUCTURE COMPLIMENT ITS FUNCTION'''

DNA, or deoxyribonucleic acid, is the hereditary material in almost all organisms. Nearly every cell in an organism body has the same DNA. Most DNA is located in the cell nucleus where it is called nuclear DNA, but a small amount of DNA can also be found in the mitochondria where it is called mitochondrial DNA, also in plants chloroplasts has DNA

The information in DNA is stored as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T). Animal DNA consists of many million bases, and more than 99 percent of those bases are the same in all organism of a given species. The order, or sequence, of these bases determines the information available for building and maintaining an organism DNA bases pair up with each other, A with T and C with G, to form units called base pairs. Each base is also attached to a sugar molecule and a phosphate molecule. Together, a base, sugar, and phosphate are called a nucleotide. Nucleotides are arranged in two long strands that form a spiral called a double helix.

DNA can replicate, or make copies of its self. Each strand of DNA in the double helix can serve as a pattern for duplicating the sequence of bases. This is critical when cells divide because each new cell needs to have an exact copy of the DNA present in the old cell. In the nucleus of each cell, the DNA molecule is packaged into thread-like structures called chromosomes. Each chromosome is made up of DNA tightly coiled many times around proteins called histones that support its structure. Coiling of the DNA is very important since the space limited.

It is stable against mutations since the strand can be separated for DNA replication/synthesis and base pairs are in the helix cylinder Hydrogen bonds between complementary base pairs are strong enough for stability, yet are weak enough that they can be separated for replication It ability to coil to a highly condensed state in order to fit in the nucleus is one other adaptation.

There is possible relationship between an optimal growth temperature (OGT) of organisms and nucleotide content of their genomes. For example, An increase in purine (A + G) load of bacterial genomes of some thermopiles is a possible primary adaptation mechanism against high temperature environment.

DNA strands have directionality. One end of a DNA polymer contains an exposed hydroxyl group on the deoxyribose; this is known as the 3' end of the molecule. The other end contains an exposed phosphate group; this is the 5' end. The directionality of DNA is vitally important to many cellular processes, since double helices are necessarily directional (a strand running 5'-3' pairs with a complementary strand running 3'-5'), and processes such as DNA replication occur in only one direction. All nucleic acid synthesis in a cell occurs in the 5'-3' direction, because new monomers are added via a dehydration reaction that uses the exposed 3' hydroxyl as a nucleophile.

DNA Conformations, DNA exists in many possible conformations that include A-DNA, B-DNA, and Z-DNA forms, although, only B-DNA and Z-DNA have been directly observed in functional organisms. These conformations interact with enzymes in our bodies and they are also involved in aspects such as DNA repair. DNA Sense and Antisense, DNA holds the genetic 'codes' to make RNA. In turn, RNA is needed because it holds the codes for the amino acids that make proteins. The antisense strand is the DNA strand that carries important information to make proteins by binding to the RNA. This antisense strand is the key for making proteins. In comparison, the sense strand is the one that does not code for RNA.

Asymmetrical nature of DNA structure- DNA molecules are asymmetrical, such property is essential in the processes of DNA replication and transcription.