SSS 2009-04-28
时间：2018-12-24 作者：英语课 分类：Scientific American(四)月
This is Scientific American’s 60-Second Science. I’m Karen Hopkin. This will just take a minute.
Many of the key molecules 1 for life have a specific direction, or handedness: DNA 2 twists to the right, amino acids to the left. Now scientists at the National Institute of Standards and Technology (or NIST) aim to take advantage of this so-called chirality to search for signs of extraterrestrial life.
When chemists synthesize organic compounds in the lab, they often wind up with a mix of molecules: half are right-handed, and half are left. But cells are a bit more particular. When life arose, our ancestors made some choices. They went with the right-handed sugars, and the left-handed amino acids, a tradition still in effect.
The scientists at NIST have come up with a gadget 3 that can see the polarized light that bounces off of molecules that show a preferred handedness. And in the Proceedings 4 of the National Academy of Sciences, they report using the device to detect the signature reflection that comes from the chlorophyll in plant leaves. If this handedness meter works well at a distance, they could load it onto a space probe—a preponderance of right- or left-handed biomolecules could mean a planet has at least simple life forms on it. And we might even find out if ET is a southpaw.
Thanks for the minute. For Scientific American’s 60-Second Science, I’m Karen Hopkin.
- The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
- Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里，大分子裂变为小分子。
- DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
- Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。
- This gadget isn't much good.这小机械没什么用处。
- She has invented a nifty little gadget for undoing stubborn nuts and bolts.她发明了一种灵巧的小工具用来松开紧固的螺母和螺栓。
- He was released on bail pending committal proceedings. 他交保获释正在候审。
- to initiate legal proceedings against sb 对某人提起诉讼