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This article rings so true to me. My father is a microbiologist - and now, so is my fiancée. I'm very lucky that I get to learn about genetics through osmosis n
by nneonneo 6y ago
This article rings so true to me. My father is a microbiologist - and now, so is my fiancée. I'm very lucky that I get to learn about genetics through osmosis now, and boy, is it ever fascinating!
I had a dining-table discussion with my dad the other day where the subject of DNA mismatch repair came up. It turns out that, in E. coli, a very simple & widely studied prokaryote, there's a mechanism called DNA mismatch repair which fixes errors which might occur during DNA copying. If an error is detected - a mismatch (e.g. a G paired with a T) - a trio of proteins (MutL, MutS, MutH) spring into action. The original template strand is already methylated - marked with an extra methyl group - at certain points in the genome (usually where there's a C followed by a G). The daughter strand, on the other hand, is usually not methylated yet. So, one of these proteins starts running down the DNA from the mismatch site, looking for a methyl group - up to 1000 base pairs away. When it finds a site with a methyl group on one side but not the other, it nicks (marks) the daughter strand, and another protein complex comes along and chops up everything from the nick to the mismatch site. The DNA polymerase then comes by and resynthesizes the whole strand.
Just three proteins are needed to drive this complex algorithm - a linear search procedure which distinguishes the mother from the daughter strand, a marking procedure which identifies the incision point, and a third to chop up the DNA and prepare it for resynthesis. What's even more bonkers is that E. coli - under stressful situations - will disable certain DNA repair mechanisms to deliberately induce more mutations. And I know that there are thousands more such pathways and complex interactions going on in cells all the time - many of which we simply haven't discovered or probed yet.
I wish that everything in biology could be explained so neatly. Unfortunately, real biology is so incredibly messy. There's just so much we don't know - and so much that we can't neatly slot into an explanation like this. But, I know now that in another life I probably would have been a biologist!
- geomark 6y ago"I'm very lucky that I get to learn about genetics through osmosis..." I see what you did there. But...is the genetics knowledge the solute or the solvent, because, well, you know (teaching biology to my homeschooled kid at the moment and we just did a unit on diffusion and osmosis, so please excuse my current state of mind)
- Cerium 6y agoI have found that educational osmosis becomes less effective over time as I fill my head with bits of information. I have to exert more pressure learning to cause the information to travel across the barrier into my mind. This also explains why you start to feel stupid after watching too much television, the osmotic action is working against your self interest.
- DrAwdeOccarim 6y agoNext step, start thinking about these systems as tools to be used in making technology. You've stumbled upon a very important thing here. Look up IDT gBlocks. Solid-phase nucleotide synthesis is only 99.9% efficient. This means when you make a 500 nucleotide long synthetic DNA strand, every other one will have an error. How do you clean-out the wrong ones? Well, you make the complementary strand, anneal them together, and pass them through a column with immobilized MutS. Guess what happens? The dsDNA with errors get bound by the enzyme and the perfect duplexes just flow right through. So out the other end is cleaner DNA. This is how biotechnology works.
- alok-g 6y ago>> If an error is detected - a mismatch (e.g. a G paired with a T) - a trio of proteins (MutL, MutS, MutH) spring into action. One additional thing should be covered in biology teaching -- Not just the process that magically "happens", but how it ends up happening. The said proteins have no free will to just spring into action. I recall being taught during high school about mitosis and meiosis, how this spindle apparatus forms, DNA strands split, etc. How do I connect what happens to the laws of Physics? I understand that I still cannot explain gravity, or why a ball falls to the floor, but biology teaching seems to leave a lot more out, and without saying so.