DNA

• The four bases found in DNA are adenine (A), thymine (T), cytosine (C), and guanine (G).
• Genetic material of living organisms is either DNA or RNA.
• DNA stands for Deoxyribonucleic acid.
• RNA stands for Ribonucleic acid.
• Genes are lengths of DNA that code for particular proteins.
• A nucleotide is made of 3 components: a Pentose sugar, a Phosphate group, and a Nitogenous base.
• In DNA, the sugar is deoxyribose, while in RNA it is ribose.
• Nitrogenous bases come in two types: Pyramidines (Thymine, Cytosine, Uracil) and Purines (Adenine, Guanine).
• Nucleotides are connected to each other via the phosphate on one nucleotide and the sugar on the next nucleotide, forming a Polynucleotide.
• James Watson and Francis Crick built a model of the structure of DNA.
• X-ray diffraction photograph of the DNA double helix.
• The Nitrogenous Bases pair up with other bases, for example the bases of one strand of DNA base pair with the bases on the opposite strand of the DNA.
• Adenine always base pairs with Thymine (or Uracil if RNA), and Cytosine always base pairs with Guanine, because there is exactly enough room for one purine and one pyramide base between the two polynucleotide strands of DNA.
• Complementary base pairing: Purines (Adenine, Guanine) pair with Pyramidines (Thymine, Cytosine, Uracil), and vice versa.
• The genetic material must contain, in a stable form, information encoding the organism’s structure, function, development and reproduction.
• The genetic material must replicate accurately so progeny cells have the same genetic makeup.
• The genetic material must be capable of some variation (mutation) to adapt to changing conditions.
• The speed of DNA replication is 3,000 nucleotides/min in humans and 30,000 nucleotides/min in E.coli.
• The accuracy of DNA replication is very precise, with 1 error/1,000,000,000 nt.