VOA常速英语:Scientists Build a Custom Chromosome

BALTIMORE, MD. — Scientists have built a custom chromosome -- a package of genetic material assembled entirely from synthetic DNA.

This engineered chromosome belongs to yeast, but experts say it can help them understand how genes work in humans as well. And it could help make these tiny living factories better at producing everything from medicines to biofuels. Students were key to the project

In a lab at Johns Hopkins University, students stitched together machine-made strands of DNA, the chemical that carries the genetic blueprints of life.

Their goal: to assemble all 6,000 genes in the genome of yeast.

Johns Hopkins geneticist Jef Boeke leads the class. He said yeast does familiar jobs, like turning grapes into wine, but they also do more than that.

“We have yeast that are used not just to make alcohol and bread, but also all kinds of chemicals, medicines, vaccines and fuels. And I think we’re going to see more and more of this in the future,” said Boeke.

And with genetic engineering, Boeke said, scientists could help yeast do those jobs better.

Plus, these one-celled creatures share about a third of their genes with us. studying their genes can teach us a lot about ourselves.

Like us, yeast cells keep their genetic material in bundles of DNA known as chromosomes. Think of each chromosome as a book of genetic instructions, Boeke said.

“The book would be made up of chapters, the chapters would be made up of paragraphs and words and, ultimately letters,” explained Boeke.

And each gene is a word made up of letters of DNA, the chemical chain that forms the iconic twisted ladder shape.

Boeke’s class has strung together all the words in one genetic book so far -- one chromosome out of yeast’s 16.

They engineered the new chromosome to let researchers shuffle genes around like a deck of cards.

“Some will have winning decks at making biofuels and some at making some other useful product,” he said.

Researchers say they are careful to consider the ethical implications of re-writing the code of life, but Boeke adds that his students are learning the basic tools of modern biology and getting excited about the possibilities.

“We could teach them how to do something at once very practical but at the same time amazing and unique,” said Boeke.

Macintosh Cornwell, a student at Johns Hopkins, said it’s helped him prepare for a career in science.

“The range of skills you learn and the amount of experience you get in such a small time period, it’s invaluable, really,” said Cornwell.

He and his class are on the cutting edge of this new world of biology.