One important outcome of the work on the expression of genes in developing embryos is sure to be knowledge that can help p

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问题 One important outcome of the work on the expression
   of genes in developing embryos is sure to be knowledge
   that can help preventing birth defects. Just as promising                   1. ______
   is the possibility of unravel the complicated wiring                        2. ______
   of the brain. A mechanic gets valuable insight how an                       3. ______
   automobile works by rebuilding car engines; similarly,
   neuroscientist can learn how the brain functions from                       4. ______
   the way it is put together. The next step pursuing the                      5. ______
   goal is to find out how the blueprint genes, the homeobox
   genes, control the expression of other genes that create the
   valves and pistons of the working cerebral engine. The
   protein encoded by the later genes could change the                         6. ______
   stickiness of the cell surface, the shape of the cell or its
   metabolism to create the characteristics peculiar to, say,
   neurons or neural-crest cells. Surface proteins may be the
   mechanism, whereby similar programmed cells stick                           7. ______
   together to form specific structures; they might also sense
   the local environment to help the cell decide what is to do.                8. ______
   Clarifying those mechanisms will engage the best talents in
   embryology and molecular biology for some times to come.                    9. ______
   What is perhaps the most intriguing question of all is if the               10. ______
   brain is powerful enough to solve the puzzle of its own creation.

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