Chris Kempes

And so people often just say bacteria as the small stuff, not realizing that there's an entire world in bacteria of diversity and different cell sizes and trade-offs and lifestyles and environments. And so even there, we're talking about half the range of body size differences that we see in mammals in terms of orders of magnitude. And so a factor of 10,000 is definitely nothing to sneeze at.

And so people often just say bacteria as the small stuff, not realizing that there's an entire world in bacteria of diversity and different cell sizes and trade-offs and lifestyles and environments. And so even there, we're talking about half the range of body size differences that we see in mammals in terms of orders of magnitude. And so a factor of 10,000 is definitely nothing to sneeze at.

Exactly. So bacteria or prokaryotes, they have some amount of internal structure. And this is something we've learned a lot more about recently. But in general, you can think of them as some sort of membrane. And sometimes that's two layers of membrane. And then inside that membrane is a bunch of more or less free-floating stuff.

Exactly. So bacteria or prokaryotes, they have some amount of internal structure. And this is something we've learned a lot more about recently. But in general, you can think of them as some sort of membrane. And sometimes that's two layers of membrane. And then inside that membrane is a bunch of more or less free-floating stuff.

That includes a free-floating genome that's not packaged in a nucleus. It includes a bunch of large molecular machines, often called macromolecules, all of the enzymes and proteins of the cell. And mostly this stuff just diffuses around and interacts in a very complicated but messy network to do all of the functions that a cell needs to do to metabolize.

That includes a free-floating genome that's not packaged in a nucleus. It includes a bunch of large molecular machines, often called macromolecules, all of the enzymes and proteins of the cell. And mostly this stuff just diffuses around and interacts in a very complicated but messy network to do all of the functions that a cell needs to do to metabolize.

to synthesize new parts and eventually to divide, to import and export material from the cell, and for larger cells to swim around and follow nutrients and make some decisions about their environment. But yes, they lack a lot of the internal structure that we see even for other unicellular organisms. So there are other single cell organisms that have more internal structure,

to synthesize new parts and eventually to divide, to import and export material from the cell, and for larger cells to swim around and follow nutrients and make some decisions about their environment. But yes, they lack a lot of the internal structure that we see even for other unicellular organisms. So there are other single cell organisms that have more internal structure,

bacteria tend to be these very simple things. Not quite the simplest life because I'm a viruses are life too sort of person. And we could get into why I think that's the case. So I would count viruses as the smallest life and the simplest example of really an enclosure and some genetic material inside that enclosure. Bacteria then have this active goopy stuff inside.

bacteria tend to be these very simple things. Not quite the simplest life because I'm a viruses are life too sort of person. And we could get into why I think that's the case. So I would count viruses as the smallest life and the simplest example of really an enclosure and some genetic material inside that enclosure. Bacteria then have this active goopy stuff inside.

Exactly. The DNA is just... So it's actually a circular chromosome in many cells. So it's a DNA that forms this entire loop. And that loop is not a rigid loop. It's malleable and moving in time. And so think about sort of a...

Exactly. The DNA is just... So it's actually a circular chromosome in many cells. So it's a DNA that forms this entire loop. And that loop is not a rigid loop. It's malleable and moving in time. And so think about sort of a...

a circular chain inside a cell that's jostling around and sort of moving all over the place while interacting with a bunch of molecules that read off the genetic information and copy the genetic information when the cell divides. And so it's in some ways sort of amazing that without much structure and in such a messy environment, we get such reliable organisms, right? Yeah.

a circular chain inside a cell that's jostling around and sort of moving all over the place while interacting with a bunch of molecules that read off the genetic information and copy the genetic information when the cell divides. And so it's in some ways sort of amazing that without much structure and in such a messy environment, we get such reliable organisms, right? Yeah.

is a sort of unbelievable number of prokaryotes on the planet. And they evolve very quickly. They live in every environment you can imagine. They divide reliably. They're just quite amazing creatures.

is a sort of unbelievable number of prokaryotes on the planet. And they evolve very quickly. They live in every environment you can imagine. They divide reliably. They're just quite amazing creatures.

Yeah, so something we like to say is that if you have a dominant physical constraint, it will also tell you where there's a wall, where something becomes... asymptotically limiting. And what I mean by asymptotically is just something goes off to infinity and you can't keep up with it, or something goes to zero and then it does you no good.

Yeah, so something we like to say is that if you have a dominant physical constraint, it will also tell you where there's a wall, where something becomes... asymptotically limiting. And what I mean by asymptotically is just something goes off to infinity and you can't keep up with it, or something goes to zero and then it does you no good.

And so often if you're writing down some optimization equation and it has physical constraints in it, you should expect to see a limit at some scale. And so we see these in lots of different groups of organisms, but particularly in bacteria, we have pretty well worked out what the lower limit and the upper limit are.

And so often if you're writing down some optimization equation and it has physical constraints in it, you should expect to see a limit at some scale. And so we see these in lots of different groups of organisms, but particularly in bacteria, we have pretty well worked out what the lower limit and the upper limit are.