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November 2008

November 30, 2008

Walking Proteins Move Cargo

Kinesin
Kinesin dimer / David S. Goodsell, Scripps Research Institute

One way to transport objects inside a cell is by the use of Kinesin motor proteins. Three things are required: a motor to move the cargo, a track along which to move it, and the cargo itself that needs to be delivered.

Motor Proteins

Proteins are essential components of cells that are involved in a number of processes. They are formed by linking amino acid molecules together in chains. The sequences of amino acids needed to build proteins are specified by genes as part of the genetic code.

Motor proteins are a special form of protein that do physical work. Remarkably, these proteins have the ability to move along surfaces, transport cargo that is attached to them, or produce force. They use the chemical Adenosine Triphosphate (ATP) as an energy source to power their movement. The motor protein myosin, for example, is involved in the contraction of muscle fibers in animals. Dynein is a motor protein that is found in flagella, the long tail-like structure that projects from certain types of cells like sperm to help the cell move.

Microtubules

Microtubules are one of the components of the cytoskeleton, the infrastructure that supports the cell. They are made by linking repeating units of the tubulin protein together. The resulting chain is then curled into a hollow cylindrical shape. They can grow or shrink to produce force, and also serve as conduits along which other cellular components can be transported.

Kinesin Cargo Transportation

Small molecules in the cell can move to where they are needed by the process of diffusion. However, larger molecules that are synthesized in the cell body are transported by motor proteins to their destinations. Kinesins are a type of motor protein that use microtubule tracks to walk along. 

Two intertwined chains with globular heads on one end form a Kinesin dimer. To move, the heads repeatedly attach and detach to the tubulin units of the microtubule track, moving everything forward in a hand-over-hand fashion. The opposite ends of the dimer drag the cargo along that they are attached to.

Thanks to Nested Universe reader Faris Naji for inspiring this topic, and discovering the attached video which shows the Kinesin protein in action.


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November 22, 2008

When Fact Meets Fiction – Learning Science the Fun Way

Books
iStockphoto / Ugur Evirgen

I don’t normally read science fiction, but Michael Crichton is an entirely different story. I fell in love with his work even before he gained a greater degree of fame with Jurassic Park and its sequels. Right from Andromeda Strain to the Sphere, I’ve enjoyed the way he combines a little bit of fact and a whole lot of fiction to spin a believable yarn about worlds of both the future and the past.

Another author who qualifies for such bouquets in my book is Dan Brown, not for The Da Vinci Code, the famous (notorious) bestseller that caused a ton of controversy, but for its sequel, Angels and Demons, which in book, was a better book than the Code. I particularly took a great deal of interest in the Large Hadron Collider and the way antimatter was explained and used to cause great mayhem and potential destruction. And when I saw the fine print that said that this fact was indeed fact and that fiction had been woven around it, I looked up the project on the Internet and read all I could about it. I admit I was a bit smug when I could tell all my friends that I knew all about this project more than a year ago, and even though they initially thought that I had turned into some kind of science junkie (which I definitely am not), they were surprised to learn that good fiction can have fact as its basis.

Science is a subject that not everyone understands easily; but when it is couched in fiction, when a compelling yarn is woven using the slightest thread of truth, it’s then that people want to learn more and discover more. That’s the best part of books, the fictional kind, because they teach you more than their subject-specific counterparts ever will. Just ask any aficionado of medical and legal mysteries – they’re bound to be familiar with a whole lot of facts, processes and procedures that relate to hospitals and the courtrooms respectively.

And that’s because they don’t consider the process as one of learning, but one of enjoyment. Reading these books are leisure activities for them, while slogging over textbooks is drab, routine work that must be done to achieve good grades. There’s a vast difference in the results achieved when a task is done just for the sake of it and when it’s really enjoyed wholeheartedly. And this delineating line is where fact meets fiction!

This post was contributed by Kelly Kilpatrick, who writes on the subject of web learning versus class learning. She invites your feedback at kellykilpatrick24 at gmail dot com


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Silicon Valley Artificial Intelligence MeetUp

MeetUp
iStockphoto / Kronick

Monica Anderson will speak about Model Free Methods and Artificial Intuition at the Silicon Valley Artificial Intelligence MeetUp at the TechShop in Menlo Park, California at 12 noon Sunday, November 23, 2008. The talk is one hour, followed by an hour discussion about any AI related topic.

Attendance is free but limited to 70 people. The event will be video recorded and may be posted on the web later.

Please join the AI MeetUp group and RSVP on the web site below if you want to attend: http://www.ai-meetup.org/events/9183657/?action=detail&eventId=9183657

The calendar page http://www.meetup.com/ai-silicon-valley/calendar is updated regularly.


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