Many people think that information technology and biotechnology will rule the 21st century. Robert Birge, a chemist at the University of Connecticut, is trying to combine them, by making computer memories out of protein.
The protein in question is bacteriorhodopsin (bR), a molecule that undergoes a structural change when it absorbs light. By using genetic engineering to tweak wild bR from a bacterium called Halobacterium salinarum, Dr Birge and his colleagues have made a variety of the molecule that they claim is well-suited to act as an element of a computer's memory. Hit with a green light, it adopts one shape. Hit subsequently with a red light, it twists itself into another. Then, if hit with blue light, it resets itself into its original state.
To make a memory from the protein, Dr Birge suspends elements made from it in a transparent plastic cube known as a cuvette. A pair of lasers arranged at right angles to one another write data into the cuvette by shining in turn on "slices" through the plastic matrix. The first laser, which produces green light, sweeps the whole cuvette, causing its protein contents to take on a shape that (in binary code) is designated as "zero". The second laser, which produces red light, then stimulates particular sites to take the second shape. This corresponds to "one" in binary code. Once the lasers are switched off, data recorded this way will, according to Dr Birge, remain stable for more than 12 years.
To read the stored data, a low-powered red laser is shone slice by slice through the cuvette. This does not disturb the conformation of the protein molecules; but those in state "zero" absorb light at this wavelength. A machine placed behind the cuvette detects this absorption pattern and translates it into the appropriate string of ones and zeroes. Once the contents have been read into a more conventional storage device, the cuvette can be wiped clean and reset by illuminating it with a blue laser.
Dr Birge says that each cuvette can now hold about seven gigabytes of data (a small laptop computer might have about this much space on its hard drive). He hopes to boost that figure to ten gigabytes by finding a better-performing variety of the protein. Only those with deep pockets, however, could afford the $25,000 cost of each device.
Luckily for Dr Birge, the deep-pocketed American air force thinks that bR cuvettes could be a good way to equip its aircraft and satellites with light, high-density devices to store the mountains of images collected during reconnaissance missions. A protein-based memory is particularly suitable for this, because the bR molecule is robust enough to withstand the barrage of radiation from space that wreaks havoc on conventional magnetic-memory devices operating at high altitude.
1. What is the passage mainly about?
[A]What will rule the 21st century.
[B]How bacterial protein can be used in computers.
[C]What we can get from bacterial protein.
[D]How to make bacterial protein.
2. The application of bR turns out to be___________.
[A]very trustworthy
[B]rather superficial
[C]somewhat contradictory
[D]quite encouraging
3. The basic problem of applying bR to computer lies in ____________.
[A]limited space on hard drive
[B]its complexity
[C]its high price
[D]its limited users
4. Which of the following is not the advantage of [1] [2] 下一页 |
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