BMS1062 Lecture Notes - Lecture 24: Zygosity, Nucleoprotein, Reca
14 Aug 2018
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Objectives : explain how double stranded dna breaks can occur understand what homologous recombination is and what happens when things go wrong understand meiosis vs mitosis and recombination during meiosis. Homologous recombination crucial for repairing double stranded dna breaks also used to rearrange dna sequences to alter versions of genes present alter timing and level of expression of the genes provides genetic variation. Main uses accurately repair double stranded breaks allows genetic exchange between a pair of homologous dna sequences during meiosis, plays a mechanical role in ensuring accurate chromosome segregation. Double stranded breaks occur due to radiation and reactive chemicals ( environmental damage) May also arise from dna replication forks that become stalled or broken ( dna replication errors) actual mechanism: occurs when a nick or gap appears in the parental dna helix just ahead of the replication fork. When the fork reaches the lesion, it falls apart resulting in one broken and one intact daughter chromosome.
