February 24, 2016 at 02:36AM

Today I Learned: 1) How many replication origins do you think there are in the human genome? That is, at how many points in the genome does the cellular replication machinery bind and start duplicating the chromosome? If you asked me over dinner, I would have guessed one per chromosome, so 23 (well, 46 under most circumstances, given diploidy and all). On further reflection, I might have answered "a few per chromosome", because if there are multiple origins, there can be multiple replication forks, which means the cell can duplicate its genome faster. The real answer? 80,000. I couldn't capitalize that for emphasis, since there are no capital numerals, so let me try that again -- EIGHTY THOUSAND, or about THREE AND A HALF THOUSAND per chromosome. Oh, and double that in a diploid, i.e. amost every human cell. That's a lot of replication forks. Incidentally, from this we can calculate the approximate deoxynucleotide consumption rate of a human cell undergoing replication. According to bionumbers (ID 104136), a single repilation fork adds about 33 nucleotides per second. This is pretty consistent with bionumbers ID 111200, which claims a replication fork velocity of about 1.5 kb/minute. With 80,000 of these forks running at once, and two strands synthesized per fork per base pair, that's a nucleotide consumption rate of about 5 million nucleotides per second per cell. If every cell in your body were to go into division at once (don't try this at home), that would be order of magnitude 5E6 * 4E13 ~ 2E20, or 200 quintillion, or 200,000,000,000,000,000,000 nucleotides per second, which is also about a third of a millimole of nucleotides every second. Nucleotides average about 487 grams per mole, so that's something like a milligram of nucleotides per second, which is about the weight (per second) of a medium-coarseness grain of sand (or a microliter, if you're familiar with those). 2) The US has the largest air force in the world, by a fair margin. No surprise there. Guess who has the second-largest air force in the world? No really, guess. ... ... It's the US navy. Thanks to Anders!!!! on this one. There's some discrepancies between different wiki pages on the subject of air power -- check out http://ift.tt/1hYFW8X, http://ift.tt/1Lb4O08, and http://ift.tt/1On2lQC -- so I'd check the numbers yourself to be sure. 3) Our country's (the US's) first war was fought alongside the French against the British government. Our *second* war, the Quasi-War (yeah), was fought *against* the French government, ostensibly on the side of the British but without much coordination or cooperation (they sold us some arms and we shared secret signals to keep from attacking each other). The Quasi-War was a roughly two-year naval war mostly consisting of massively effective pirating of US merchant vessels by the French and massively effective raiding, capturing, and sinking of French military vessels by the US navy. The war has its roots in the rather massive monetary debts owed to the French government by the US for loans paid during the Revolutionary war a couple decades before. When the french government was toppled in their own Revolution, the US (not sure whether it was ambassadors, legislators, or the president) decided that they weren't going to pay back their debt because it was owed to a previous government, not to the current revolutionary government (also, the US was trying to repair ties with Britain). This led to some rather antagonistic diplomatic exchanges between the two countries, eventually leading the French to decide they'd get their money back in the standard way that states seem to have extracted money from one another -- by privateering (state-sponsored piracy). You know, it seems like the US got into a lot of wars over its merchant fleet. The Quasi-War was the first. In the two years before a treaty was signed, the US fleet of about 25 naval vessels won a number of engagements against the french, losing only one ship (which was later recaptured). This, however, didn't stop the French from capturing over *2000* merchant ships. So really, the whole thing was a bit of a win-win scenario -- France got its money back, and the US navy gained some much-needed credibility in the European stage.