Wednesday, May 10, 2006


Deoxyribonucleic acid (DNA) is a nucleic acid (“a complex, high-molecular-weight biochemical macromolecule composed of nucleotide chains that convey genetic information”) (2) that are in the form of a double helix. It is able to replicate itself due to its double helix structure. “DNA contains genetic instructions that specify the biological development of all cellular forms of life. DNA is a long polymer of nucleotides and it encodes the sequence of the amino acid residues in proteins using the genetic code mostly a triplets code of nucleotides” (1).

"The DNA molecule is a chemically linked chain of nucleotides. Each DNA molecule consists of sugar (deoxyribose-it has five Carbons and three Oxygen), a phosphate and one of five kinds of nucleobases (bases). DNA strands are composed of nucleotide subunits called polymers.” DNA has five kinds of nucleotides which are commonly referred to by the identity of their bases (1). The bases are adenine (A), thymine (T), uracil (U), cytosine (C) and guanine (G). Uracil (U) is found in the DNA when cytosine (C) is chemically degraded”.

DNA is sometimes referred to as a heredity molecule because it carries genetic propagation (when more DNA is produced from the original strand) of most inherited traits.” DNA can be transferred after been replicated from the parent to the offspring during reproduction. Each and everyone of us has DNA; we have inherited our genomes from our parents. A genome of an organism carries the whole hereditary information of an individual that is encoded in the DNA” (4). Each individual inherits 23 chromosomes from each parent including the X-chromosome (mitochondrial DNA that we inherit from our mothers and Y-chromosome from our fathers (1).

The way in which the DNA strands stay associated is determined by complementary pairing. Each base forms hydrogen bonds A bonds with T and G with C. the hydrogen bonds between A to T is a double bond and between G to C is a triple bond.

Since DNA is a double stranded helix it can also unfold into two single strands by the process called DNA replication. “The two resulting double strands which are identical, each synthesize a new strand by the process called semiconservative replication (the method in which DNA is replicated in all known cells) (5). The DNA molecule is always double stranded when it unfolds another strand is synthesized unless the DNA is mutated (change in genetic material)”.

"DNA contains the genetic information that is inherited by the offspring and this information is determined by the sequence of the base pairs. A DNA strand contains genes and areas where gene regulation takes place. Genes can be viewed as a cookbook or blueprint” (3).

The significance of DNA to us as human beings is that we are able to trace back our ancestors for example scientists used DNA in order to try to find the missing link between “Apes to Man”. Scientists used DNA in order to trace African Eve eight daughters so DNA is so important. DNA contains genes that parents pass on to their children so the generations can be traced back to our ancestors.


1. Wikipedia contributors. DNA [Internet]. Wikipedia, The Free Encyclopedia; 2006 May 01, 23:16. UTC [cited 2006 May 3]. Available from:

2. Wikipedia contributors. Nucleic acid [Internet]. Wikipedia, The Free Encyclopedia; 2006 May 01, 12:48. UTC [cited 2006 May 3]. Available from:

3. Wikipedia contributors. DNA replication [Internet]. Wikipedia, The Free Encyclopedia; 2006 May 2, 04:25 UTC [cited 2006 May 3]. Available from:

4. Wikipedia contributors. Genomes [Internet]. Wikipedia, The Free Encyclopedia; 2006 May 3, 04:39 UTC [cited 2006 May 3]. Available from:

5. Wikipedia contributors. Semiconservative replication [Internet]. Wikipedia, The Free Encyclopedia; 2006 Feb 3, 04:39 UTC [cited 2006 May 3]. Available from:

Lethabo Mosomane




Tel: 27 12 841 2133

Fax: 27 12 842 3676



  • Your assignments still have hyperlinks. To remove just right click on the word and choose "remove hyperlink". Cheers Gud Luck!

    By Anonymous Anonymous, at May 10, 2006 1:26 PM  

  • You have not used quotes to indicate copying from a reference. This is plagiarism.

    By Blogger Gwen, at May 15, 2006 4:52 PM  

  • i will use them thanks we had 6 days to write 12 assignments we didn't have enough time to check our work so i will try and fix it thanks Gwen

    By Blogger lethabo, at May 16, 2006 10:04 AM  

  • i've just fixed everything

    By Blogger lethabo, at May 16, 2006 12:04 PM  

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