If all the DNA in my body vanished right now, how long would I take to die? What would kill me?

ren5311 · 8 months

This is a surprisingly interesting question. My first thought was that with no DNA, you'd be unable to replace cells, so you'd have massive GI and skin problems that would kill you in a few days.

But you're right that cells might die first in the absence of appropriate regulation. So, then I figured it would be the cyclins or CDKs that would fail to regulate cell cycle, causing aberrant growth. But you've got no DNA to replicate!

The method of cell death would have to be either triggered apoptosis or necrosis. ~~ But the apoptotic response requires significant transcriptional activity...~~ Maybe calpstatin would fail to inhibit calpain, which would destroy the cytoskeleton and release lysosomal enzymes? Alternatively, necrosis could result from disturbances in energy processing, but I'm having a hard time thinking of a metabolic protein with a lifetime less than an hour.

I also like discupula_vitae's idea of heat shock proteins being needed to regulate correct protein conformations after changes in temperature, which is illustrative of the fact that without DNA and related transcriptional machinery, all your cells would be profoundly sensitive to the most minor changes in their environment.

On a system level, you would probably die from massive release of pancreatic enzymes or internal bleeding from leaky blood vessels.

hughk · 8 months

Well people who have had high radiation doses without other injuries such as the workers who were exposed to the core after Chernobyl (causing major DNA/RNA damage) tend to die within 72 hours or so. Initial symptoms of heavy radiation doses are related to the failure of the gut lining (which is normally continually replenished).

Note that the DNA/RNA is not totally destroyed by the exposure but it, along with other complex molecules are pretty much disrupted.

Dr_Roboto · 8 months

Another thing to consider is that DNA has a net charge that is counter-balanced by ions in the cytosol and there is a lot of it. Your cells would suddenly have a lot of unbalanced charges which would probably cause many proteins to denature or assume nonfunctional conformations. The result would be much like what happens when you cook an egg.

klenow · 8 months

I've been thinking this over; it's a fascinating intellectual exercise.

The first hurdle would be the disruption of the electrochemical gradient due to the loss of the negative charge of the DNA. This would be uninteresting, though, because it means that every cell would just lose the ability to do anything instantly and you'd just drop dead; fraction of a second. All muscles would shut down (Calcium can't flow anymore because the cytosol is too positively charged), including the heart. All nerves would instantly lose the ability to transnduce action potentials. Instant death. We're talking maybe seconds to live. Probably less than one second.

But since we're in magicland anyway, let's say you replace the DNA with an equivalent charge. No charge loss, you survive the first second.

Now you have a few timers going, and they race to the finish. One would be the gut epithelium. It has a half life of 3-5 days. Since you no longer can make anymore gut cells, you almost immediately start getting ulcers in your gut tract. It's only a matter of time before you lose enough blood to die; and you can't make more blood anymore. I'd estimate this timer is around a day.

The other one would be growth factors. Certain cells in your body require constant signals to stay alive. As these fade away, these cells will decide to die. This one is harder to gauge; I don't know all the factors involved & I don't know their half lives. Cell death would be complicated, too, as apoptosis (cell suicide) generally requires transcription or damaged DNA to work. But there are DNA independent mechanisms. The loss of signal would cause a sustained calcium flux. This would cause the release of cytochrome c (a protein that is always there) into the inner membrane space of the mitochondria. This would shut them down. Once that happens, no more ATP gets made and the cell will be dead in less than a minute when the ATP runs out.

My guess is that you'd die over the course of about a day, maybe less, from a combination of these two things.

discipula_vitae · 8 months

Your death seems pretty imminent. Your body needs that DNA at pretty much all times to create new proteins to give you life. Proteins that are created all have different "lifespans" but they are pretty short because the body needs to be able to regulate at all times. So the first time your body temperature changes and you body can't make new proteins to correct it, you will be at risk. But it will probably sometime even sooner than that. Not having the correct proteins to metabolize or expel some sort of compound right away and being poisoned by some byproduct of an already on going chemical process seems most likely. Very interesting question.

TexSC · 8 months

Your cells have proteins just to check the integrity of the DNA. My bet is that some of these proteins would detect the DNA was missing, and trigger apoptosis immediately. I think you would die in seconds.

dcherub · 8 months

So I was thinking about this and it seems to be you'd have to look at which metabolically necessary protein or enzyme has the shortest half life, then count up until you wouldn't have enough of said enzyme in your cells to sustain general metabolism. I'm thinking it's probably one of the key TCA cycle enzymes. Without DNA your house keeping genes wouldn't be able to replenish these enzymes and once they wear out your cell wouldn't have energy to keep itself running. You'd probably become tired... then take a nap then peacefully pass away. I hope.

kitchendancer · 8 months

I really enjoyed reading through the other answers, but I'm going to throw a more metaphysical biological food-for-thought into the ring as well.

It's actually really difficult to comprehensively define "life" and "death" from scientific standpoint, even though we all feel that we intuitively know what it means.

Most biological definitions of "life" require:

capacity to grow

metabolism (chemical and biochemical reactions within an organism)

ability to respond to stimulus

ability to reproduce

At the moment of losing your DNA, you would completely lose the ability to reproduce and the capacity to grow, though you keep the other two to some degree thanks to the biological material you already possess. Is that satisfying the definition enough in order to call yourself still alive? Maybe... maybe not. Using the above as yes/no binary qualities, a PCR reaction reasonably satisfies "metabolism" and "ability to respond to stimulus (temperature, cofactors, salts, etc)"

Maybe you'd be instantly non-living according to biology, even if your processes keep ... processing.

*I accidentally a word.

rz2000 · 8 months

[deleted]

Alonsa · 8 months

The seeds of Abrus precatorius don't destroy a DNA, but they're effectivelly blocking a proteosynthesis by inactivating the 26S subunit of the ribosome. One seed is able to kill human (3 mkgs of abrine which corresponds LD50 < 100 ng/kg).

Again, it tooks more than three days to kill the human with proteosynthesis blocked.

captainnobliviouss · 8 months

With all protein production being stopped within minutes (RNA degradation), protein degradation will follow. Once the electronegativity of the cell changes with the disappearance of DNA, RNAs and proteins (which include channels of all sorts that regulate ion flow), all sorts of voltage gated channels will open, the ones with the most destructive potential being Ca+2 channels. Membrane integrity will be jeopardized, internal Ca+2 levels will go up, reactive oxygen species production will kick in, lysosomal enzymes will be released and necrosis will set in.

Once necrosis starts, it'll cause a chain reaction that will kill every single cell and damage every type of tissue in the body partly because reduncancy systems to keep necrosis in check themselves stop functioning and partly because necrosis often cannot be confined successfully even with the aformentioned systems in place.

My estimate: death within hours (<24hrs), perhaps as soon as 30 minutes - 1 hour. Loss of conscioussness in seconds.

IAmA_scientist2 · 8 months

I imagine the immediate problem would be that without DNA, you would not be able to produce mRNA which would then be used to produce proteins. It's probably the same as if you treated your cells with cyclohexamide (inhibitor of protein biosynthesis).

cowhead · 8 months

You can find out by taking alpha amanitin. The main job of your DNA is to serve as a template for making RNA and thus protein. This drug blocks that process completely. But, take that away, and you should still have some proteins left to keep you going for awhile. This is an interesting question, because I would have thought that this "while" would be hours. Instead, it appears to be days. People with amanitin poisoning last up to 10 days! Of course, they probably haven't ingested enough to block all new protein synthesis, but still....

salgat · 8 months

Your DNA produces all the enzymes and proteins you need for your body. I'm pretty sure within a day nearly all your cells would die since they wouldn't be able to do anything.

arabidopsis · 8 months

Apoptosis will kill you.

You will probably see specks of yourself fall off, as your cells commence cell destruction. You will see necrosis, and probably not feel pain, but notice parts of you going black, most likely from the most dividing cells to the least, so you will literally sit there watching yourself rot.

AdmOxalate · 8 months

There are a whole set of constantly transcribed genes called "housekeeping genes," which would no longer be transcribed once the DNA is gone. Many regulatory proteins have half lives on the order of minutes. I think you would die on the order of minutes to an hour as your mitochondria die and cellular respiration halts; You are probably already unconscious by the time that happens though.

philyd2000 · 8 months

Absence of neurotransmitters would cause the phrenic nerve to no longer initiate breathing (same with all respiratory muscles). Without a ventilator, you'd last only minutes with this limitation.

[deleted] · 8 months

Nearly immediately. Protein synthesis would fail, and pretty much every system would begin to fail immediately from neuron firing to muscle control

pizearke · 8 months

If I recall correctly, tissue that constantly needs new cells, such as intestinal tissue, wouldn't be able to replace itself. You also wouldn't be able to create proteins such as insulin or hemoglobin.

There's probably more than that, but that's what came to my mind.

mojotoad · 8 months

Running with the premise, wouldn't the sudden appearance of so many micro-vacuums in every cell (minus red blood) cause significant systemic shock, up to and including sludge-syndrome?

[deleted] · 8 months

This is like asking if a computer's Hard Drive is disconnected, how long does it have before it crashes.

[deleted] · 8 months

a few seconds?

8 months

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