Hello. I have a little question about 'crossing over'. Sorry for the scientifical terms, i was unable to find all of them, so i guess this will be hard to understand (i would appreciate if you correct me in spelling, and give me the scientifical terms that i missed). I understand tha during crossing over, part of the non-identical chromatides forming a tetrad are exchanged. I also know that the chromatides are made of a DNA molecule (and ... proteins ?), which are made of neucluotides, and that a gene is a group of codons, being 3 neucuotides. So, in conclusion, during 'Crossing over', some neucluotides are exchanged. Now, my question is, is it possible that not a whole gene gets exchanged between the two chromatides (iow, half a gene, or quarter a gene). If so, wouldn't this cause a lot of problems ? Thanks (if you see the question is not clear enough, please ask me to clear it ).