Introduction to Parkinson's Science/DNA

What is DNA?
DNA is an abbreviation of DeoxyriboNucleic Acid and is the name given to a string of proteins which provides the hereditary material contained within cells.

DNA is made up of 4 base compounds called ‘nucleotides’, viz:-

•	Adenine (A) paired with Thymine (U)

•	Guanine (G) paired with Cytosine (C)

•	Cytosine (C) paired with Guanine (G)

•	Thymine (U) paired with Adenine (A)

Nucleotides are aggregated into sets of three termed 'codons'. This gives 64 possible triplet combinations, but certain combinations give rise to the same shaped molecular structures so that functionally there is a limited set of amino acid structures.

These are:-

DNA has been likened to a recipe book for proteins and each recipe is termed a ‘gene’.

How is DNA structured?
Amino acids are aggregated into linear strings. The strings consist of genes separated by intergenic material so that the genes occur at intervals along a string like pearls on a necklace, viz:-

GENE - - -INTERGENIC---GENE---INTERGENIC—--GENE and so on.

Intergenic material has sometimes been designated (erroneously)- as ‘junk DNA.

A gene consists of a Start codon, followed by  a sequence of amino acids and then a Stop codon.

The most commonly occurring Start codon is AUG (Methionine)

The most commonly occurring Stop codons are:- UAA   UAG   UGA.

Mutations occur when DNA material is copied and one of the nucleotides in a codon (generally the third one) is accidentally changed.

What are chromosomes?
Organisms may have several gene strings called chromosomes’  the number of chromosome varies from species to species. A human being has 46 chromosomes, an earthworm has 36, the Adder’s Tongue Fern has about 1,200.

Further Reading and Viewing
Images for DNA

http://www.google.co.uk/search?q=dna&hl=en&qscrl=1&rlz=1T4SKPB_enGB345GB345&prmd=imvns&tbm=isch&tbo=u&source=univ&sa=X&ei=Gq5pUKv8M8ir0QW-34GABg&sqi=2&ved=0CDMQsAQ&biw=1024&bih=567

DNA Handbook

http://ghr.nlm.nih.gov/handbook/basics/dna

Interactive teaching site.(DNA)

http://www.dnai.org/

Animated primer

http://www.dnaftb.org/