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http://www.FreeScienceLectures.com We travel inside nucleus to see how the DNA replicates. When DNA replicates its strands are separated by enzine helicase. Single-stranded DNA binding proteines keep the strands from (...?). One DNA strand encodes the leading strand using DNA Polymerase III. Just watch to see what is going on.

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1859 - Achemical was extracted from nuclei and named 'nuclein'.

1944 - 'Nuclein' was recognised as genetic material.

Late 1940s - Erwin Chargaff discovered a pattern in the number of bases in DNA.

1951 - Linus Pauling and Robert Corey showed that proteins have a helix structure.

1952-3 - Rosalind Franklin and Maurice Wilkins produced X-ray diffraction pictures of DNA. They showed that the molecule had a regular, repeating structure.

1953 - Francis Crick and James Watson published their paper 'A structure of Deoxyribose Nucleic Acid', in the scientific journal, Nature.

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The organic bases pair in a specific order:

Adenine(A)  always pairs with Thymine(T) with 2 hydrogen bonds

Guanine(G) always pairs with Cytosine(C) with 3 hydrogen bonds

DNA

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DNA takes the form of a twisted ladder, called a DOUBLE HELIX.

The rungs of the ladder are made of the pairs of organic bases.

A section of the DNA  is called a gene, which code amino acids to make proteins

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DNA is made up of pairs of 4 organic bases connected to between a sugar called deoxyribose and phospahtes, hence DNA.

These 4 organic bases are Adenine (A), Thymine (T), Guanine (G), Cytosine(C)

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DNA is short for deoxyribonucleic acid
and contains the genetic code for making proteins needed for growth, repair and reproduction