I’ve taught several times a graduate course on biophysics, the first instance of which I blogged about here. I love teaching this class, and students seem fond of it as well. I’m teaching it again next Fall (2023) but with a twist: it will now be a combined undergraduate / graduate course. The motivations are … Continue reading Introduction to Biological Physics — an old and new course
Since I was a child I’ve wondered why an hour feels like an hour and not a second or a year, and, relatedly, what sets the speed of our thoughts. Like every aspect of life, the answer is governed by the physical phenomena that underlie biological processes. In the case of signals traveling through our … Continue reading What sets the speed of thought? — What is biophysics? #14
Herds of wildebeest, swarms of bees, and schools of fish all provide mesmerizing displays of coordinated motion. Fish, birds, and other animals numbering even in the millions can act as one not through centralized control, but through local actions and decisions, as each individual assesses the speed and orientation of its neighbors. This self-organization is … Continue reading How can a swarm swarm? — What is biophysics? #13
[Announcement: I’m giving I gave a virtual book talk Tuesday, Nov 29, 2022! Video recording link.] Many living things move. Panthers pounce, snakes slither, dolphins dive. Organs can move (such as beating hearts), and even individual cells can be motile, such as the immune cells that crawl through our tissues. How far down in scale … Continue reading Can a Molecule Walk? — What is biophysics? #12
This was supposed to be a short, simple post about how brittle stars use their skeletons to help them see. It turns out, however, that the brittle stars have misled us, and what we thought we knew twenty years ago has been overturned by new observations. The question of what and how various creatures see … Continue reading Do Sea Stars See? — What is biophysics? #11
About a recent paper from my lab: Deepika Sundarraman, T. Jarrod Smith, Jade V. Z. Kast, Karen Guillemin, and Raghuveer Parthasarathy, “Disaggregation as an interaction mechanism among intestinal bacteria,” Biophysical Journal (2022). Some bacteria stick together; others do not. We have seen these variations among bacteria inside the zebrafish gut, and it’s probably the case … Continue reading Things Fall Apart; The Bacterial Cluster Cannot Hold
Your genome is the totality of your genetic instructions, embodied in your DNA, of which each cell carries a copy. (Two copies, but let’s ignore that.) How big is your genome? Often, the answer is given in terms of base pairs — the rungs of the ladder of double-stranded DNA. For humans, it’s 3 billion … Continue reading How Big Is Your Genome? — What is biophysics? #10
In a charming letter published in 1774, Benjamin Franklin described an experiment in which he had poured “not more than a teaspoonful” of oil onto a pond, which he found sufficient to calm the water despite a choppy wind. What, you may be wondering, connects Franklin, ponds, tears, and salad dressing? In the last “What … Continue reading How are tears like salad dressing? — What is biophysics? #9
You’re full of amazing liquids. How can a liquid be amazing? One way is to have properties that change depending on how strongly the liquid is pushed. The speed at which a fluid flows depends on the force that’s driving it, and the proportionality between force and flow is known as the viscosity of the … Continue reading How are tears like ketchup? — What is biophysics? #8
No. Nor are atoms, viruses, or grains of sand. It is a fundamental truth that everything is in motion, shaking, twisting, and turning at random with an intensity that depends on temperature, motionless only at the unattainable limit of absolute zero. Though this is a manifestation of physics, its consequences for biology are profound and … Continue reading Are molecules ever still? — What is biophysics? #7
The Eighteenth Elephant 