Saw this elsewhere and, while it is amusing, my next response was thinking that it can’t be anywhere close to correct. Or am I missing something?
Which part do you find unreasonable? Assuming the 37.5 MB/sperm is correct, then the rest follows, yes? I don’t know how they got 37.5MB, but I have heard similar numbers bandied about.
I just read this:
“OP’s calculations are incorrect. The human genome has ~3.15 billion base pairs. Since DNA has four nucleotides, we should multiply by 2 to get the equivalent number of “bits” in our genome. 6.30 billion bits = 750 MB of data per diploid cell. Sperm cells, however, have only half as much genetic information, so there should be 375MB/sperm and a transfer rate of 15.87TB/3 sec”
http://www.reddit.com/r/funny/comments/h9cks/1_sperm_has_375mb_of_dna_information_in_it_that/
It’s not completely clear what it means but if it’s just talking about ejaculation itself then that’s not really a data transfer. If you throw a USB drive across the room you haven’t “transferred 1GB in less than a second…”. I’m not sure if you can really make a genuine comparison but to do it you’d have to talk about how long it takes the ovum to grab and ‘process’ the DNA information in a sperm. I don’t know how long that takes but I doubt it’s seconds!
Right, that’s what I was thinking. That the 37.5MB sounded way too small. Thanks for finding that link.
There is a whole lot of redundant information in that “data packet” - all the X/Y chromosomes are the same, and from sampling, all you could get would be a single reconstruction of the original diploid DNA (750Mb).
Si
[slight hijack]
My semen has exactly zero sperm (vasectomy years ago). I’m assuming it still contains my DNA, and I could be positively identified were I a rape suspect. Is this correct?
[/slight hijack]
NOTE: Not seeking legal advice; I am not, have not ever been, and never plan to be a rape suspect, etc. etc. etc.
One should also consider that the information has very low entropy, since all sperm will share DNA with each other. If you factor out the redundancy, then the total information content is going to be pretty close to 750MB, no matter how many sperm are in the ejaculate.
On edit: What si_blakely said. (Sorry, I don’t know how I missed that post.)
While we’re making the comparison… this is clearly like those file sharing sites. You have to wait 15 minutes between downloads, and have a pretty good chance of getting a virus. 
Yes. The SDSAB speaks.
I’m no scientist, but don’t all of our cells contain our DNA? Including the cells that make up the non sperm portion of ejaculation?
Ejaculate mostly isn’t made up of cells at all. Aside from the sperm, the only cells in there are going to be the ones that just happened to slough off from the inside of your plumbing.
Not all body fluids contain cells. And no, not all cells contain DNA. Red blood cells, for example, lack a cell nucleus and organelles, and therefore contain no DNA whatsoever.
I do wonder if the amount of sloughed-off cells is sufficient that a normal DNA test on a normally obtained forensic sample would actually find any from a vasectified male ? (How do they swab a rape victim’s private parts and not get a large number of her cells in the mix? or do they just ignore them?)
It sounds more like “there’s a chance”, the real question being “how big a chance”? Obviously from a vial that contains only the sample, I imagine eventually they would find a DNA sample. But in the real world?
To answer the OP - it’s only 750MB, but there’s plenty of backups so you should get a good copy in about 9 months.
I have identical twins, does this mean I spawned a mirror of my RAID, or was my girlfriend actually a high availability cluster.
Never thought I could make “high availability cluster” sound naughty…
OMG! I’ve been wasting information all these years!
Yeah, so actually, the information content is just a vector, really.
After spermatogenis has been completed in the semniferous tubules, it travels a long and convolvuted pather before ejaculation. The Sertoli cells secrete fluid which creates pressure on the spermatozoa pushing the sperm and fluid into straight tubules, then the rete testis, and then into a series of coiled efferent ducts in the epididymis that empty into a single tube called the ductus epididymus. The sperm matures there and is stored there. It helps propel them during sexual arousal by peristaltic contraction of its smooth muscle, into the ductus vas deferens. The ductus deferens can store viable sperm for up to several months. The ducts store and transport sperm, but the accessory sex glands secrete most of the liquid portion of semen, which protects sperm and facilitate their movement. The accessory sex glands include the seminal vesicles, the prostate, and the bulbourfethal gland. The seminal vesicles secrete an alkaline, viscous fluid that contains fructose, prostaglandins, and clotting proteins (which differ from those in blood). The alkaline nature helps to neutralize the acidic environment of the male urethra and female reproductive tract. The fructose is used for ATP production by sperm. Prostaglandins contribute to sperm motility and viability.
The prostate secretes a milky, slightly acidic fluid (pH 6.5) that contains: (1) citric acid used by sperm for ATP production; (2) proteolytic enzymes, such as PSA, pepsinogen, lysozyme, amylase, and hyaluronidase, which eventually breaks down the clotting proteins from the seminal vesicles; and (3) seminalplasmin, an antibiotic. Prostatic secretions make up approx. 25% of the volume of semen.
During sexual arousal, bulbourethal glands secrete an alkaline fluid that protects sperm by neutralizing acids from urine in the uretha. They also secrete mucous that lubricates the end of the penis and the lining of the urethra.
The prostatic secretions give semen a milky appearance, and fluids from the seminal vesicles and bulbourethra glands give it a sticky consistency.
[source: *Anatomy and Physiology, from Science to Life *, Jenkins, Kemnitz, and Tortora, John Wiley & Sons, Inc. 2007]
I believe much of the semen contains bodily productions that contain cells. Whether those cells contain your DNA is another question, but the clotting proteins probably do.
Under normal circumstances, only one sperm’s worth of data is transferred, if that. The rest is signal loss.
Now that’s a mouthful!
(sorry)