BIOL 102 Chapter Notes - Chapter 16: Semiconservative Replication, Dna Replication, Dna Virus
Document Summary
Semiconservative replication- each dna double helix is half old dna (template) and half new dna. Virus- dna enclosed by a protein coat. Infects a cell and takes over its machinery to produce more viruses. Histones- responsible for the first level of dna packing into chromatin. Bubble is formed where dna goes from double strand to single strand. Dna is replicated using both strands as a template. Dna grows in 5-prime to 3-prime direction. Replication fork- y-shaped region at end of replication bubble where dna strands are elongating. Replication proceeds from both directions from each fork and independent pieces are then joined together. Helicase- untwist double helix at replication forks. Single-strand binding proteins- keeps unpaired dna from re-pairing. Topoisomerase- corrects over-winding by breaking, swiveling and rejoining dna strands. Rna polymerase (primase)- can bind single-stranded dna and use it to make complementary rna: this rna serves as a primer.