Category Archives: Universe

The current A—list celebrity of the virus world, coronavirus — officially SARS-CoV-2 — has caused quite on stir despite being absurdly tiny. Size—wise, a single virus particle is to a grain of sand what a grain of sand is to a three—story house.

Put another way, if the virus were the size of a grain of sand, a human would be 18 km tall — tall enough that airplanes at cruising altitude would hit them somewhere in the torso. Amazing how much damage a tiny grain of sand can do to a world of giants that big.

These silly little lunar-module—looking robot friends are the single deadliest entity on our planet. There are more bacteriophages on Earth than every other organism combined. They’re also ruthless murderers. But luckily for us, they only target bacteria. They’re very picky killers, since each kind of bacteriophage specializes in killing only a certain kind of bacterium. This may make them a perfect hyper—targeted antibiotic for humans to use to fight the growing threat of superbugs: bacteria that have built immunity to common antibiotics.

Optical microscopes max out here because when we go any smaller, we’re below the wavelength of the visible light spectrum — so light passes right by or around objects instead of bouncing off of them.

Arguably the smallest living thing, the bacterium Mycoplasma genitalium — named as such because it’s found in the human genital tract — is shaped like a spoon. To actually use it as a spoon, you’d have to shrink yourself down so small that an actual spoon was the size of Switzerland. Since it is so small and doesn’t have a cell wall this bacterium is very hard to be observed with a microscope.

The visible light spectrum is pretty narrow. As the wavelength of visible light grows, the light works its way from blue to red — and then it becomes infrared and we can’t see it anymore. Heat gives off infrared light, so if our eyes could see infrared light, we’d be able to see the temperature of objects just by looking at them — something you can do with an infrared camera.

One of the smallest free—living bacteria, this little caterpillar—shaped guy is so small that if you had one in your hand, you’d have to scale yourself up until your hand was the size of London to make the Pelagibacter ubique the size of a real caterpillar. Ubique means “everywhere” in Latin, and that’s very appropriate: Millions of them can be found in every liter of seawater, accounting for a quarter of the bacterial biomass in the oceans. The more you learn about ocean water, the more upsetting it is to accidentally get a gulp in your mouth.

Viruses are small and rather simple, but the mimivirus doesn’t care about your restrictive labels and decided to be big and complex instead. The name mimi comes from the fact that it seems to mimic microbes because of its unusual size.

To stay alive, organisms need energy. One of the most brilliant innovations in evolutionary history happened when the mitochondrion, which used to be its own independent single—cell organism, agreed to give up its independence and become an organelle inside another cell. Its job would be to focus on converting food into energy, and in return, it wouldn’t have to worry about survival anymore. It’s been a great partnership that made organisms so efficient they were able to form larger creatures — like us.

For 1.6 billion years, life on Earth was only simple singIe—celled organisms, called prokaryotes. Then, somehow, something got tweaked, and complex cells called eukaryotes were born. Unlike prokaryotes, eukaryotes have a nucleus and sexually reproduce. If it turns out that intelligent life is exceedingly rare in the Universe, one possible reason why may be that the jump from simple to complex cells is an unfathomably unlikely miracle. Or maybe it’s a regular occurrence on planets with life — no one knows for sure!

Chromosomes are intense. Over a billion of them could fit in a cubic mm, but there’s over 5 cm of DNA strand packed into each one. Altogether, the forty—six chromosomes in each of your cells contain about 2 m of DNA, all jammed into the cell’s nucleus. X and Y chromosomes are our names for the “sex chromosomes”. The Y—chromosome is only a pm long, the X—chromosome a bit longer. All human eggs contain an X chromosome, while half of all sperm cells contain an X chromosome and the other half contain a Y chromosome. We all start out as female embryos, but after 6—7 weeks, fetuses created by a Y—carrying sperm begin the process of virilization and develop into males.