Introduction to Genetic Analysis 498

Introduction to Genetic Analysis 498 - 44200_15_p481-520...

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497 15.2 Changes in chromosome structure mosomal rearrangements by breakage can be induced artifcially by using ionizing radiation. This kind oF radia- tion, particularly X rays and gamma rays, is highly ener- getic and causes numerous double-stranded breaks in DNA. To understand how chromosomal rearrangements are produced by breakage, several points should be kept in mind: 1. Each chromosome is a single double-stranded DNA molecule. 2. The frst event in the production oF a chromosomal rearrangement is the generation oF two or more double-stranded breaks in the chromosomes oF a cell (see ±igure 15-19, top row at leFt). 3. Double-stranded breaks are potentially lethal, unless they are repaired. 4. Repair systems in the cell correct the double-stranded breaks by joining broken ends back together (see Chapter 14 For a detailed discussion oF DNA repair). 5. IF the two ends oF the same break are rejoined, the original DNA order is restored. IF the ends oF two diFFerent breaks are joined together, however, one result is one or another type oF chromosomal rearrangement.
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This note was uploaded on 01/10/2011 for the course BIOL BIOL taught by Professor Johnson during the Spring '08 term at Aberystwyth University.

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