Introduction to Parkinson's Science/DNA

What is DNA?

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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:-

AMINO ACID ABBREVIATION LETTER COMBINATIONS
Alanine Ala A GCU GCC GCA GCG
Aspartic acid Asp D GAU GAC
Cysteine Cys C UGU UGC
Glutamic acid Glu E GAA GAG
Glutamine Gla Q CAA CAG
Glycine Gly G GGU GGC GGA GGG
Histidine His H CAU CAC
Isoleucine Ile I AUU AUA
Leucineine Leu L UUA UUG CUU CUC CUA CUG
Lycine Lys K AAA AAG
Methioninine Met M AUG
Phenylalanine Phe F UUU UUC
Proline Pro P CCU CCC CCA CCG
Serine HSer S UCU UCC UCA UCG AGU AGC
Threonine Thr T ACU ACC ACA AGG
Tryptophan Trp W UGG
Tyrosine Tyr Y UAU UAC
Valine Val V GUU GUC GUA GUG

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

How is DNA structured?

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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?

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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

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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/

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