Perhaps when blowing your nose, or the nose of a sick child, you’ve wondered where all this stuff comes from. How can one nose make so much mucus? This is #17 in our series of biophysical questions (#1, #16). The answer involves electrical forces and the physical character of mucus. Mucus, the gooey liquid secreted … Continue reading How can one nose make so much mucus? — What is biophysics? #17
Viruses encode their genomes in RNA or DNA, which they pack into a tiny space. For example, Varicella zoster, the virus that causes chickenpox and shingles, stuffs a double-stranded DNA molecule about 40,000 nm in length into a shell about 200 nm in diameter. This is even more impressive than it may seem because DNA … Continue reading Can viruses explode? — What is biophysics? #16
What makes one microscope better than another? A few weeks ago I co-ran a week-long Physics and Human Physiology day camp for high school students, part of the University of Oregon’s “SAIL” program that especially targets low-income students. I’ve written about SAIL before (2019, 2017, 2014) — this was our 14th Physics + Human Physiology … Continue reading A Few Flavors of Microscopes — SAIL recap, 2023
Biophysics is full of deep puzzles that are surprisingly simple to state. Imagine a pill shaped bacterium. (Your body is home to trillions.) It grows and then cleaves itself into two equally sized progeny. How does it know where its middle is? For us, looking at the bacterium, finding the middle is an easy task. … Continue reading How does a bacterium find its center? — What is biophysics? #15
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
