BIOL 101 Lecture 10: DNA
21 Jan 2019
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Knew dna contains four types of nucleotides. Examined dna for many species: amount of a t g c in dna varies from species to species. In each species, amount of a = t and g=c. Dna is a polymer (long molecule made of small molecules) All nucleotide contains phosphate, 5-carbon sugar and nitrogen containing base: building block of dna. Franklin"s x-ray diffraction data: structure showed dna to be a helix with some portions repeating over and over. Dna structure is a double helix (twisted ladder) Deoxyribose sugar and phosphate molecules are bonded, forming sides with bases making inside: atgc (individual-covalent) hydrogen bonds (weak) up rungs of ladder. Complementary base pairing of a&t and c&g. Hydrogen bonding between bases holds halves of helix together. Process of copying dna before cell division. Each strand serves as template for new strand. Semiconservative: each new dna molecule is made of one parent strand and one new strand. Replication requires: unwinding-helicase, complementary base pairing.
