I've stumbled upon an interesting short article http://www.npr.org/templates/story/story.php?storyId=4225769 It's about the possible danger of Y-chromosome in men loosing its genes throughout the evolution, because it is unpaired (the X-chromosomes are always paired and thus can correct random errors). That could inflict danger on reproduction, however MIT researchers claim that the Y-chromosomes have found an other way to survive by encoding the major genes as palindromes in DNA... Now, what I can't understand is the following: what I assume (please correct, if wrong): 1. DNA is a long double-stranded (ds) molecule. It splits into two single-stranded (ss) counterparts only during replication. This is the place where the mutations can take place, however there always remains the second single-stranded counterpart, which will probably remain unchanged. 2. chromosomes are nothing else than a complete (3 billion base pairs), double-stranded DNA molecules. what I do not understand: 1. How to X-chromosomes couple? Can two double-stranded DNA's couple? 2. What is the danger with Y-chromosome? It is dsDNA, and is "secured" by the fact that mutation will occur only in a single strand, while the other one will survive. Why is the palindromic algorithm needed? 3. How does DNA implement palindromic algorithm? Does it simple bend and copy itself like that: "__" turns into "U" Thanks!