BI236 Lecture Notes - Lecture 2: Guanine, Karyotype, Variable Number Tandem Repeat
Document Summary
Slides 2 the structural basis of cellular information: dna, ~3. 2 billion base pairs in every cell build the build the human genome. Genes form 1. 5% of the human genome. A gene: a segment of the dna that encodes for a protein, about 30 000 genes in humans. A very long, continuous piece of dna. Contains many genes, regulatory elements and other intervening nucleotide sequences. Eukaryotic chromosomes: structurally complex as dna is associated with high amounts of proteins. Double helix: long polymer with sugar phosphate backbone. Chargaff"s rules: a + g = t + c, # of purines (a/g) = # pyrimidines (c, t, u) Crucial experimental evidence x-ray diffraction data of wilkens and franklin. Phosphodiester bonds join the 5" carbon of one nucleotide to the 3" carbon of the adjacent nucleotide. Purine-pyrimidine pairing: consistent with chargaff"s rules; demonstrate complementarity; function as a template for replication. Nucleotide = base + pentose + phosphate group. B-dna: normal form of dna, right-handed helix.
