system
Given the following post, respond as if you're commenting on Reddit:
human
What would happen if all my DNA disappeared?

I brought up this question with a scientist friend of mine, and given she was unable to answer, I leave it to you:

What would pass if all of the DNA in my body (from every cell) were simultaneously broken down into peptide bonds? 

Obviously I wouldn't be able to have children, but I'm thinking that all my cells would also cease to function, leading to instant death.

What do you think?
gpt
Short answer: yes, you would die. It probably wouldn't be instantaneous, though.

Longer answer: cellular function depends on the transcription of DNA into messenger RNA, and the translation of the messenger RNA into proteins. Because most proteins in the body are constantly being recycled (degraded, remade and replaced), the loss of DNA would mean that your cells wouldn't be able to regenerate all the proteins lost to normal turnover. Eventually, this would lead to cell death, because all of the functions that keep you alive depend on proteins - for example, all the enzymes that are required for cellular respiration and metabolism of food into energy that can be used by cells. However, it wouldn't be instantaneous, because cells have some reserves of key proteins available for exactly this reason (in case of DNA damage). There are also small reserves of messenger RNA available that the cell would probably transcribe in order to regenerate proteins lost to normal turnover. But once the protein and mRNA reserves were expended, the cell would begin to die as the proteins required to maintain its structural integrity began to be degraded.

Provided your cells don't die due to lack of proteins involved in cellular function, they would be unable to divide to form new cells, because the process of cell division depends on the replication of DNA. No DNA, no new cells, so tissues with normally rapid cell turnover (like the lining of the gut) would begin to die.

Actually, your example isn't all that far-fetched. One of the main ways that radiation damages the body is through catastrophic DNA damage. Cells become unable to generate new proteins and divide (as described above). Therefore, the cells that normally divide most quickly/most often (such as gut lining epithelial cells, hair follicle cells, etc.) die first, leading to some of the most well-known symptoms of radiation poisoning, like nausea and hair loss.