Changes

Most commonly as a double-stranded [[helix]] comprising two complimentary molecules held together by hydrogen bonds, this is commonly called "dsDNA" (double-stranded DNA).<ref>Single-stranded DNAs (ssDNA) do exist in certain [[bacteriophage]]s, however they cannot be replicated without first creating the complimentary strand to use as a template.</ref>  The  [[nucleotide]]s which are the "building blocks" of DNA have three main parts: A nitrogenous base (the "letters" in the sequence), a [[sugar]], and a [[phosphate]] group.  When nucleotides are joined into DNA strands, they form a chain with the phosphate group of one nucleotide binding to the ribose of the next.

Most commonly as a double-stranded [[helix]] comprising two complimentary molecules held together by hydrogen bonds, this is commonly called "dsDNA" (double-stranded DNA).<ref>Single-stranded DNAs (ssDNA) do exist in certain [[bacteriophage]]s, however they cannot be replicated without first creating the complimentary strand to use as a template.</ref>  The  [[nucleotide]]s which are the "building blocks" of DNA have three main parts: A nitrogenous base (the "letters" in the sequence), a [[sugar]], and a [[phosphate]] group.  When nucleotides are joined into DNA strands, they form a chain with the phosphate group of one nucleotide binding to the ribose of the next.

DNA strands "compliment" each other by having compatible sequences, allowing the bases on one strand to form bonds with the bases on the other strand.  There are four nitrogenous bases, Adenonine (A), Cytosine (C), Guanine (G), and Thymine (T).  Under the base pairing rules, A pairs with T and G pairs with C.

DNA strands "compliment" each other by having compatible sequences, allowing the bases on one strand to form bonds with the bases on the other strand.  There are four nitrogenous bases, Adenonine (A), Cytosine (C), Guanine (G), and Thymine (T).  Under the base pairing rules, A pairs with T and G pairs with C. This allow cell to repair the DNA correctly if only one strand is damaged.  

DNA contains [[gene]]s that encode for [[protein]]s. These are produced by the DNA first being turned into m[[RNA]] and then into polypeptides (this process is called the [[Central dogma of molecular biology|central dogma]] of molecular biology). All organisms use DNA as their hereditary material. Offspring of sexually reproducing organisms contain DNA from both parents.

DNA contains [[gene]]s that encode for [[protein]]s. These are produced by the DNA first being turned into m[[RNA]] and then into polypeptides (this process is called the [[Central dogma of molecular biology|central dogma]] of molecular biology). All organisms use DNA as their hereditary material.  

 

Most of the cells in multi-cellular organisms (human including) retain a complete copy of all DNA of the first cell from which the organism started to grow. It is often possible to clone the organism, or part of it, from a single cell, while doing so with a human cell has severe ethical implications.

 

All DNA required for a cell to grow into organism is called genome. A cell containing only one genome is called a haploid cell. Humans are diploid (one genome from each parent). Other organisms may have cells with more genomes, for instance, a cell of bread [[wheat]] contains six (hexaploid).

==History==

==History==