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In a recent paper in the journal Science, Venter and his colleagues ___1___ that they had created the smallest living and reproducing organism. Their creation is a simple cell, with only the genes that are essential for life; it is larger only than those found in viruses and other entities that rely on hosts(寄主) for ___2___ functions.

Venter and his team created their organism through a process of ___3___ and error. They began by using their knowledge of biology to deduce the minimum set of genes that would be required for life. However, that approach ___4___.

The most important result of the Venter team's work was to ___5___ how little we know about the basic biology of life. Most of the 473 genes take care of housekeeping: They make proteins, keep DNA in good repair, and are ___6___ for the cell's membrane (薄膜) and cytoplasm (細(xì)胞質(zhì)). But there are 149 genes whose function is unknown. In other words, the purpose of nearly one-third of the genes, which needed to keep the organism ___7___, and reproducing remains a ___8___.

Of the 149 genes with unknown functions, 70 have a structure that at least hints at their role in the cell. But we know nothing about the other 79, except that in these organisms, in this environment, life is ___9___ without them.

All of this implies many exciting discoveries ahead. And yet, when it comes to practical, commercial objectives, the news is ___10___ more sobering.

A) additional

B) announced

C) assessed

D) considerably

E) essential

F) failed

G) impossible

H) separately

I) inquiring

J) mystery

K) alive

L) occasions

M) responsible

N) reveal

O) trial