Author: paddlefish

Scott and I did some scientific research on Mars, and created these documentaries (works in progress) about our findings:
episode 1
episode 2

When I’m bored I love to read about the Mars Expedition Rovers. After nearly two years the machines are still running, driving around up there on another planet taking pictures of things…..
Mars Exploration Rover Mission: Home

Ever wonder how tiny little seedlings know to send their roots one way and their shoots the other? This behavior is called Gravitropism. While a lot is known about this process, much of it is still a mystery.
Within the tips of growing roots or shoots are specialized cells called statoliths. These cells have one outstanding visible feature. (Visible with a microscope, that is.) Statoliths have tiny grains of starch in their cytoplasm.
A current theory of gravitropism goes like this: The grains of starch, being heavier than the rest of the cell, will settle to the bottom side of the cell. (This action can be observed with a good microscope.) Somehow, and this is the part that is yet unknown, this action results in release or redistribution of the plant hormone auxin on the same side of the statolith. Auxin encourages growth in plant shoots. Thus if a plant shoot is growing sideways the bottom part will receive more auxin and cause the shoot to grow upwards. Plant roots behave the opposite way : Auxin slows growth in plant roots. That has the net result of roots growing downwards.
Although this simple model was proposed in the 1930s, the process still isn’t fully understood. Many organelles, such as the Golgi apparatus and the mitochondria, are thought to be involved in the signal transduction from the starch grain to the production of auxin.

I had just about finished a post about how cool the Unix underpinnings of Mac OS X are. I used as an example the story of how I recovered some deleted files from a compact flash card by simply using the /dev/disk2 “file” and perl. However, that high praise got lost when my computer crashed. So I’ll instead leave you with this story : Blogs are great but remember that browsers don’t save anything when your computer crashes.

Not feeling to inspired to write today. But here are some fun science links:
Danielle thought that these pictures were neat:

(Ultraviolet pictures of the sun from SOHO.)
Caroline likes the Birdhouse cams.

10 years = 3653 days = 87,672 hours = 315,619,200 seconds
(also equal to 260.928571 fortnights)

This week at knitting club I painted a picture. Becka says it was more fun to be at knitting when I was there. How sweet!

Here is a slideshow of some bird pictures I took last weekend.
If the slideshow doesn’t work, let me know. It is kind of an experiment.

Becka says I should write something science-like so my page isn’t blank.
I thought I would relate one of my Bio prof’s pet peeves. It has to do with Macromolecules ( not to be confused with Macromedia ). Macromolecules are large molecules (usually protein) – they are measured in a unit called “daltons” or “kilodaltons” (kDa). One dalton is a measure of the mass of a molecule, and actually it is the same as the molecular mass. But I think biochemists use the term Dalton just so they can confuse people…. or because a dalton is usually measured using a centrifuge or electrophoresis, instead of with more exacting means such as mass spectrometry.
So the impressive thing about macromolecules is just how large they can be. For example a small molecule like water has a molecular mass of 18. Keratin, a major constituent of skin weighs in at 67,000 (67 kDa). Yeah, that’s big. But that’s nothing compared to polymers; polymers are repeating chains of molecules. DNA is a polymer. Lots of structural proteins are polymers, too. For example, collagen, microtubules, and intermediate filaments. In their polymer form, these things weigh in a millions and millions of Daltons. Actually, taken to the extreme, a car tire is actually one giant molecule — a polymer or polymers. How many Daltons is a car tire? Well, it is on the order of 6.02 times 10²³…
Diffusion across a membrane is greatly affected by the size of a molecule. Small molecules can fit through the small gaps in the membrane whereas large ones can’t. That’s why you can lose water through your skin on a hot dry day without ever sweating. That’s also how your lungs can take oxygen out of the air you breathe. Or maybe you’ve noticed that if you go swimming in fresh water after a while you really need to pee even though you haven’t been drinking anything; the water diffused into your body. But you don’t need to worry about most bad things getting into your skin when you swim. They’re usually too big to diffuse through your skin.
Anyhow, my Bio Prof’s peeve was for the hand lotion commercials that talked about how their product revitalized skin. They would have a diagram showing a cross section of the skin, with arrows showing the deep penetration of the collagen in the lotion. The problem is that collagen is a gigantic macromolecule; it cannot diffuse into your skin because it is too large. Instead it just sits on the surface and is all slimy or maybe after a while it gets crusty. Probably the only thing in lotion that does penetrate the skin is the water and oils; so some vaseline or shortening is probably just as effective.

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