The Structure of DNA DNA Deoxyribonucleic acid DNA

The Structure of DNA

DNA Deoxyribonucleic acid = DNA • Composed of Nucleic acid made up of nucleotides joined into long strand or chains by a covalent bond

Nucleic Acids and Nucleotide • Nucleic Acids – Long molecules found in the cell nuclei – Made of smaller components (parts) – Linked together to form long chains

Nucelic Acids and Nucleotides (cont) • Nucleotides – The building blocks of nucleic acids – 3 basic parts • A 5 carbon sugar = deoxyribose • A phosphate group • A nitrogenous base

Nitrogenous Bases and Covalent Bonds DNA has 4 kinds of nitrogenous bases – Purines • Adenine • Guanine – Pyrimidines • Cytosine • Thymine Commonly referred by their first letters-A, G, C, T

Strand of Nucleotides

The Double Helix • The DNA double helix is formed by using complementary base pairing (i. e. , adenine bonds thymine and cytosine bonds guanine). • Mnemonic – Alex Trebec (Adenine bonds to Thymine) – George Clooney (Guanine bonds to Cytosine) • complementary base pairing held together by hydrogen bonding in the sugar-phosphate backbone.

Double Helix

Solving the Structure of DNA Erwin Chargaff (1905 -2002) • Biochemist • Austrian • Immigrated to USA 1935 • Chargaff’s Rule – Discovered equal amounts of Adenine & Thymine • (A=T and G=C)

Solving the Structure of DNA (cont) Rosalind Franklin (1920 -1958) • English • Physical Chemistry • Franklin’s X-ray – DNA are twisted strands around each other – Made of two strands

Watson & Crick • James Watson • American • Zoologist • Francis Crick • English • Physicist • Solved the structure of DNA (1953) • 1963 Nobel Peace Prize