parm Profile picture
Nov 25 8 tweets 4 min read Read on X
A friend asked me to explain DNA, RNA, and epigenetics. he said that others had tried before, but it didn’t click for him.

I happen to play the piano, so I gave him a simple, albeit imperfect, analogy.

After this analogy, he finally understood! Here’s the piano analogy.

🧵 Image
Imagine a piano with 30,000 keys. Each key represents a gene.

Nearly all of your somatic cells have the exact same piano—the same keys, the same genes. So why does a nerve cell look different from a cheek cell?

Because they’re playing different pieces on the identical pianos. Image
Image
The piano is just a set of keys! The music—the composition—is the result of playing specific keys in a particular sequence and rhythm.

Pressing a key to play a note is like expressing a gene to produce mRNA. Image
Playing a note multiple times => multiple mRNA molecules from that gene.

Within a cell, the pattern of mRNA expression changes over time, just like the notes change over time in a musical score.

At any given moment, a fraction of the keys are being played. Image
Epigenetics is like the way the piano is played.

Some keys are easy to press; others harder to reach or require more effort.

Some keys might be muted or locked in certain cells; impossible to play there but functional in others. some keys play indirectly when you press another. Image
Image
These differences to a key, like heavier key, muted key, hard to reach key, can be written on the keys themselves (for one cell). Here’s a register of various epigenetic changes in “keys”

As before, this register may change based on cell, type of cell, etc. Image
These performances are recorded into songs, much like proteins are synthesized based on mRNA templates.

Proteins are the final products—they have specific structures and functions, giving cells their unique characteristics.

The mRNA (the notes you play) might degrade quickly, but the proteins (the recorded songs) can remain in the cell as long as needed.Image
Image
So, even though every cell has the same “piano,” the diverse “music” played leads to different cell types and functions.

I hope this analogy makes DNA, RNA, and epigenetics clearer!

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More from @prmshra

Nov 27
In a surprising paper published in Nature, scientists accomplished what sounds impossible: using genes from a single-celled organism to create mouse stem cells, which eventually developed into a living, breathing mouse. Image
Animal multicellularity emerged ~700mn years ago.

The genes in this study—from choanoflagellates, ancient single-celled organisms—are somewhat of evolutionary relics.

They predate multicellular life and now appear to have played a foundational role in animal development. Image
Choanoflagellates don’t form stem cells, but they have versions of Sox and POU genes.

In animals, these same genes drive pluripotency—the ability of stem cells to turn into any cell type. Image
Read 11 tweets
Nov 22
we recently saw an insane discovery in biology, which if true, in my opinion, makes extraterrestrial life far far more likely.

🧵 Image
new research suggests that life on Earth became surprisingly complex very early, reshaping our understanding of life’s origins and its implications for the existence of life elsewhere in the universe. Image
a paper about the Last Universal Common Ancestor (LUCA) hypothesis reconstructed the genome of our LUCA, dating it to about 4.2 billion years ago…

…just a few hundred million years after Earth formed 4.5 billion years ago. Image
Read 19 tweets
Nov 1
i had the chatGPT search extension on for about 10 minutes and reverted back to google and some plex. search holds potential, but here's why it's not good enough *yet*.

why: i want as many links as possible when researching. if i want something with context, perplexity will give me a long list of citations with a cohesive answer. chatGPT search is a nice addition to chatGPT itself, but it's not my search engine atm, unfortunately.

also, instead of making it the default search engine, installing an extension that overrides the default on chrome feels suss. but i'm going to wait to see if there's a reason for this.
a few more notes: asking a followup has returned the same answer for me, similar to how perplexity was in its early days. the search query is not fully parsed and understood yet, especially when there's parts to the query.

o1 is a powerhouse. search is a welcome addition, but does not yet hold anywhere close to a competitive advantage.

i don't like that the extension necessarily overrides the search engine until you disable that setting. it's too early to fully commit to something like this and i wish there was so much more in the extension than this setting
also when i exit search in a chat, i want normal gpt back, but it seems to persist being in search mode

i would like the gpt experience well enmeshed into the search chat agent but they are completely distinct from each other
Read 8 tweets
Jul 8
Schrödinger’s “What is Life?” is a book of magic

predicting phenomena decades before they were discovered empirically

the magic of physics : pivotal for developing molecular biology

I’ve read this book tens of times

let’s explore the key predictions.

🧵OPEN THE THREAD🧵Image
aperiodic crystals
the book posited genetic information must be stored in some “aperiodic crystal,”

a stable molecular structure that could encode information in its configuration rather than through simple repetition

Franklin's DNA X-ray crystallography, decades later:Image
this concept vastly foreshadowed the discovery of DNA’s structure and function with remarkable accuracy

DNA double helix, with its precise sequence of base pairs, essentially fits Schrödinger’s description of an aperiodic crystalImage
Image
Read 15 tweets
Jun 15
there's a SIGNIFICANT piece of legislation which could change biopharma in america. no one seems to be talking about it on X.

BIOSECURE aims to decouple from Chinese contract firms. This could affect over 120 drugs in development.

let's talk about it. 🧵
the main issue at hand is the US biopharma's reliance on Chinese outsourcing for cost-effective research.

this comes with risks related to intellectual property (IP) theft and potential ties to the Chinese government. this is what BioSecure is about.
BioSecure is progressing: The House Committee on Oversight and Accountability recently approved an updated draft.

this set a deadline of 2032 for US companies to sever ties with specified Chinese firms like WuXi and BGI Group.
Read 12 tweets
May 28
Heard of Ozempic/Wegovy? These drugs are part of a class of medications called GLP-1 agonists.

In 2023, Science named GLP-1 agonists Breakthrough of the Year for their potential to combat "diabesity", 1 year after JWST won the same award. Let's ask why.

🧵OPEN THE THREAD🧵Image
GLP-1 - glucagon-like peptide-1 - is a hormone that plays a key role in regulating blood sugar levels.

you may have heard of insulin-glucagon dynamics.

GLP1:
- enhances insulin secretion
- inhibits glucagon release
- slows gastric emptying, making you feel fuller for longer.Image
now let's talk incretins: a group of metabolic hormones, including GLP-1 but also GIP, that stimulate decrease in blood glucose

after eating, they enhance insulin secretion in "anticipation" i.e. even before blood glucose levels become elevated

10.1111/j.2040-1124.2010.00022.xImage
Read 23 tweets

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