医学遗传学人类染色体畸变.pptx

末代沙皇尼古拉二世的公主斯塔西娅
安娜-安德森
1956电影”真假公主”
10 人类染色体畸变 chromosome aberration
Any type of change in the chromosome structure or number (deficiencies, duplications, translocations, inversions, etc.).
Although it can be a mechanism for enhancing genetic diversity, such alterations are usually fatal or ill-adaptive, especially in animals.
1. factors inducing chromosome aberration
A. Ionizing radiation
Ionizing radiation produces rearrangements of the genome.
When irradiation occurs during the G0/G1 phase of the cell cycle, large-scale rearrangements appear as exchange-type chromosome aberrations at the next mitosis. Such aberrations can alter cellular phenotypes, and are important in various areas of biology:
Analyzing chromosome aberrations helps characterize repair/misrepair pathways involved in the processing of DNA damage. Ionizing radiation has some unique features as a probe of such pathways. Compared to other genotoxic agents, it produces copious quantities of DNA double strand breaks (DSBs), and its timing can be controlled more accurately.
Moreover, initial radiation damage has a discrete, stochastic character that can be modulated by using different kinds of radiation (. a -particles versus x-rays) having different ionization densities.
The spectrum of different radiation-induced chromosome aberrations is informative about the geometry of chromosomes during interphase, and vice versa.