BSCI170 Lecture Notes - Francis Crick, Dna Replication, Hydrogen Bond
Document Summary
Cells maintain a genetic program directing faithful reproduction. Information directing this must be stored and protected. Information must be read out in a way that cells can understand. Information must be transferred unchanged to the next generation. Double helix: dna structure, two strands that run opposite each other (5" 3" and 3" 5", hydrogen bond connects nucleotides, sugar-phosphate backbone. Information is stored in dna: transfer of information to proteins is irreversible. A beautiful result: specific pairings suggest a possible copying mechanism for genetic material. Dna replication: prokaryote: e. coli (bacterium, prokaryote, one piece of circular dna, 4. 6 million base pairs, copied in as little as 20 minutes. Dna replication: eukaryote: homo sapiens (human, eukaryote, 46 chromosomes (46 linear pieces of dna, 6. 4 million base pairs, copied in a few hours. Dna replication: three basic steps, initiation, elongation, termination, we will take them in turns.
