BIOL 3134 Lecture Notes - Lecture 3: Xeroderma Pigmentosum, Heteroplasmy, Dna Replication
Document Summary
Dna replication: dna replication error rate: 1 in 108 bases, a wrong dna base will be left in place, 30 mutations per genome every cell cycle. Dna repair: repair enzymes fix 99% of dna replication errors. Dna repair disorder: xeroderma pigmentosum (xp, rare autosomal recessive genetic disorder, lacks the ability to repair dna damage caused by uv. Mitochondrial inheritance: phenotypes are often highly pleiotropic because, multiple copies, heteroplasmy. Gene linkage: genes that are close on the same chromosome are said linked , genetically, it is the failure of two genes to assort independently in meiosis. Linked genes, and hence the phenotypic characters, are inherited together: exception to independent assortment, for two genes on different chromosomes, the inheritance of one allele does not influence the chance or inheriting the other allele. Crossover: chromosomes recombine during prophase i of meiosis, crossing over occurs at random locations, ensures that hereditary variability is maintained.