Crossing over occurs during?
927440
i'm pretty sure crossing over occurs during meiosis which during synapsis of homologous pairs during prophase I. i think its C
1129931
Didn't happen to me.\n\n\nBut I heard that this happens on "South Park", so it has to be true!
1099254
well, i dont think theres a cheat to that, but it would sometimes happen, it happend to me once, one was a boy and the other was a girl
1135818
Loved the other answers but in case you are interested in genetics here is the answer. Crossing over permits the generation of greater genetic diversity. Without crossing over the only diversity generated would be be shuffling whole chromosomes but during crossing over some genetic material from the maternal and paternal chromosomes is actually exchanged leading to form a chromosome that is different from both the maternal and paternal chromosome. By being able to generate this greater genetic diversity there is a greater range of phenotypes for natural selection to act on. And since genetically robust populations are more robust to changes in the environment they can evolutionarily more successful.
295237
20 minutes.\n\nAt minute 0, persons C (13) and D (17) begin crossing.  At minute 13, person C is finished and person B (7) starts.  At minute 17, D is finished and A (3) can start.  At minute 20, both A and B finish.
862238
Cross overs happen between gene locations furthur because there is more distance between to for the chromosomes to touch and cross. If they are closer, there is less area for these chromosomes to touch and exchange genetic information. 1 map unit = about 1% cross overs. If something is 10 map units appart, there is about 10% crosss over and 20 = 20% and so on. If you think about it, its like fighting with two swords. say one gene is at the tip and the other is at the handle (far genes). The chances of your opponent hitting your sword in that region is more likely than between the the tip and 1 inch down from it (close genes).
344370
SOMETIMES THAT IS EXACTLY WHAT IS GOING ON!!! AND IT ACTUALLY HAPPENS QUITE OFTEN WHEN TWO PEOPLE ARE IN SYNC!!!
801991
Independent Assortment:\nThe chromosomes of each parent sort independently in the production of gametes, so any combination of the chromosomes is possible in the offspring.\n\nCrossing Over:\nThe swapping of segments of a chromosomes between each other.  Crossing Over creates novel combinations of alleles for various gene loci.  These combination of alleles were not present in either parent.
103544
Nondisjunction.  \n\nNondisjunction occurs when homologous chromosomes fail to separate during meiosis.  This results in two cell with two copies of the chromosome (when it should one have one) and two cells with none (remember that meoisis produces four haploid cells).  If the cell with the extra copy fertilizes/is fertilized by a normal haploid gamete, the result will be a trisomy.  If a cell that's missing its copy of the chromosome combines with a normal haploid cell, there result is monosomy.\n\nThe other three choices (inversion, translocation, and crossing-over) involve changes in sequence, rather than chromosome structure or number.
683738
How do you really know it did cross? Everyone assumes the chicken crossed but maybe it's a myth.
215941
Mabye a crossover would be nice.
83115
It happens during meiosis, when the gametes are being formed. You know how chromosomes, in diploids, divide so that half of them go into one of the eggs/sperm and the other half go into the other, so that there's one of each in the gamete?\n\nWell, that is a way to re-combine the genetic material so that the offspring will have some from mom and some from dad. It's like having two sets of encyclopaediae, and combining them so that two new sets are produced, each with books from the two parents.\n\nNow imagine you have Volume 21 of the encyclopaedia from mom, and Vol. 21 from dad. You could assign one or the other to the new set being formed, but you want even more variety in the information.\n\nSo you take pages from one Volume 21 and _switch_ them with the equivalent pages from the other Volume 21.\n\nThat is crossing over and recombination. It increases the amount of possible children generated enormously.\n\nIt happens just before the chromosomes are segregated. In humans, we have 23 pairs of chromosomes. During meiosis, those 23 pairs split, forming 2 sets of 23 pairs each (chromatids). Those sets separate, and within each set the pairs recombine--that is, they cross over each other and exchange segments. Just like switching equivalent pages between the two same-numbered volumes of an encyclopaedia set.\n\nThat way the two sets of pairs, who will go on to form four new gametes, contain chromosomes that are neither identical to mom's nor to dad's, but a combination of segments of the chromosomes from both.
70294
The answer to this question is, in fact, infinite. There are an infinite number of possibile combinations due to process called crossing over. But because of the number of chromosomes humans have (23 pair), even with out crossing over there is a pretty impressive number of possible combinations. To figure that out all you have to do is figure out how many possible chromosomal combinations for each parent. Because their are 23 pair, the number of chromosome combinations, based on pure random selections for the gametes would be 2^23 or  8,388,608 combinations. This is true for both parents, so if square that number you get the pottential number of combinations two people could create through random segregation of chromosomes through meiosis (gamete production) -- that number is 70,368,744,000,000.\n\nBut please remember there are an infinite number more possibilities than this because meiosis isn't the only mechanism used to create genetic diversity in living things. The amount of crossing over that will occur -- a process in which DNA is traded between maternal and paternal chromosomes creating two hybrid versions of the original chromosomes that are now neither completely maternal or paternal -- is impossible to predict with any certainty.
604175
You know people who are actually already in the service are capable of crossing over to other branches, it happens all the time in the reserves. So I don't think you should have a problem doing so. The Marine recruiter will make it difficult no doubt but you should be able to...I'll be back. I'm gonna check something for ya...
775498
Did something like this actually happen?
149305
Changing the partner between rounds.
983608
When it goes the other direction?  Really.