以mRNA为模板,合成蛋白质的过程()。
A、复制
B、转录
C、翻译
D、反转录
E、遗传学中心法则
Eat More, Weigh Less, Live Longer
Clever genetic detective work may have found out the reason why a near-starvation diet prolongs the life of many animals.
Ronald Kahn at Harvard Medical School in Boston, US, and his colleagues have been able to extend the lifespan (寿命) of mice by 18 per cent by blocking the rodent's (啮齿动物) increase of fat in specific cells. This suggests that thinness--and not necessarily diet--promotes long life in "calorie (热量卡) restricted" animals.
"It's very cool work," says aging researcher Cynthia Kenyon of the University of California, San Francisco. "These mice eat all they want, lose weight and live longer. It's like heaven."
Calorie restriction dramatically extends the lifespan of organisms as different as worms and rodents. Whether this works in humans is still unknown, partly because few people are willing to submit to such a strict diet.
But many researchers hope they will be able to trigger the same effect with a drug once they understand how less food leads to a longer life. One theory is that eating less reduces the increase of harmful things that can damage cells. But Kahn's team wondered whether the animals simply benefit by becoming thin.
To find out, they used biology tricks to disrupt the insulin (胰岛素) receptor (受体) gene in lab mice--but only in their fat cells. "Since insulin is needed to help fat cells store fat, these animals were protected against becoming fat," explains Kahn.
This slight genetic change in a single tissue had dramatic effects. By three months of age, Kahn's modified mice had up to 70 per cent less body fat than normal control mice, despite the fact that they ate 55 per cent more food per gram of body weight.
In addition, their lifespan increased. The average control mouse lived 753 days, while the thin rodents averaged a lifespan of 887 days. After three years, all the control mice had died, but one-quarter of the modified rodents were still alive.
"That they get these effects by just manipulating the fat cells is controversial," says Leonard Guarente of the Massachusetts Institute of Technology, who studies calorie restriction and aging.
But Guarente says Kahn has yet to prove that the same effect is responsible for increased lifespan in calorie-restricted animals. "It might be the same effect or there might be two routes to long life," he points out, "and that would be very interesting."
第 41 题 Ronald Kahn and his colleagues can make mice live longer by.
A.offering them less food.
B.giving them a balanced diet.
C.disrupting the specific genes in their fat cells.
D.preventing them growing larger.
根据下面材料,回答题。
Eat More, Weigh Less, Live Longer
Clever genetic detective work may have found out the reason why a near-starvation diet prolongs the life of many animals.
Ronald Kahn at Harvard Medical School in Boston, U.S., and his colleagues have been able to extend the lifespan (寿命) of mice by 18 per cent by blocking the rodent&39;s (啮齿动物) increase of fat in specific cells. This suggests that thinness--and not necessarily diet--promotes long life in"calorie (热量卡) restricted" animals.
"It&39;s very cool work," says aging researcher Cynthia Kenyon of the University of California,San Francisco. "These mice eat all they want, lose weight and live longer. It&39;s like heaven."
Calorie restriction dramatically extends the lifespan of organisms as different as worms and rodents. Whether this works in humans is still unknown partly because few people are willing to submit to such a strict diet.
But many researchers hope they will be able to trigger the same effect with a drug once they understand how less food leads to a longer life. One theory is that eating less reduces the increase of harmful things that can damage cells. But Kahn&39;s team wondered whether the animals simply benefit by becoming thin.
To find out, they used biology tricks to disrupt the insulin (胰岛素) receptor (受体) gene in lab mice, but only in their fat cells. "Since insulin is needed to help fat cells store fat, these animals were protected against becoming fat," explains Kahn.
This slight genetic change in a single tissue had dramatic effects. By three months of age,Kahn&39;s modified mice had up to 70 per cent less body fat than normal control mice, despite the fact that they ate 55 per cent more food per gram of body weight.
In addition, their lifespan increased. The average control mouse lived 753 days, while the thin rodents averaged a lifespan of 887 days. After three years, all the control mice had died, but one-quarter of the modified rodents were still alive.
"That they get these effects by just manipulating the fat cells is controversial," says Leonard Guarente of the Massachusetts Institute of Technology, who studies calorie restriction and aging.
But Guarente says Kahn has yet to prove that the same effect is responsible for increased lifespan in calorie-restricted animals. "It might be the same effect or there might be two routes to long life," he points out,."and that would be very interesting."
Ronald Kahn and his colleagues can make mice live longer by__________. 查看材料
A.offering them less food
B.giving them a balanced diet
C.disrupting the specific genes in their fat cells
D.preventing them growing larger
根据短文回答 41~45 题。
Eat More, weigh Less, Live Longer
Clever genetic detective work may have found out the reason why a near-starvation diet prolongs the life of many animals.
"It's very cool work,"says aging researcher Cynthia Kenyon of the University of California,San Francisc0."These mice eat all they want.10se weight and live longer.It's Like heaven."
Calorie restriction dramatically extends the lifespan of organisms as different as worms and rodents.Whether this works in humans is still unknown,partly because few people are willing to submit to such a strict diet
But many researchers hope they will be able to trigger the same effect with a drug once they understand how less food leads to a longer life.One theory is that eating less reduces the increase of harmful things that can damage cells.But Kahn's team wondered whether the animals simply benefit by becoming thin。
To find out,they used biology tricks to disrupt the insulin(胰岛素)receptor(受体)gene in lab mice—but only in their fat cells."Since insulin is needed to help fat cells store fat,these animals were protected against becoming fat,"explains Kahn.
This slight genetic change in a single tissue had dramatic effects.By three months of age,Kahn's modified mice had up t0 70 per cent less body fat than normal control mice,despite the fact that they ate 55 per cent more food per gram of body weight.
In addition,their lifespan increased.The average control mouse lived 753 days,while the thin rodents averaged a lifespan of 887 days.After three years,all the control mice had died,but one—quarter of the modified rodents were still alive.
"That they get these effects by just manipulating the fat cells is controversial,"says Leonard Guarente of the Massachusetts Institute of Technology, who studies calorie restriction and agin9.
But Guarente says Kahn has yet to prove that the same effect is responsible for increased lifespan in calorie-restricted anima.1s."It might be the same effect or there might be two routes to long life,"he points out,"and that would be very interesting."
第 41 题 Ronald Kahn and his colleagues can make mice live longer by().
A.offering them less food.
B.giving them a balanced diet.
C.disrupting the specific genes in their fat cells.
D.preventing them growing larger.
Passage 5
Once they decided to have children, MiShel and Carl Meissner tackled the next big issue: Should they try to have a girl? It was no small matter. MiShel’s brother had become blind from a hereditary (遗传的)condition in his early 20s, and the Meissners had learned that the condition is a _1_ passed from mothers to sons. If they had a boy, he would have a 50 per cent chance of having the condition. A girl would be _2_. The British couple&39;s _3_ about gender selection led them to Virginia, US where a new sperm (精子)-separation technique, called MicroSort, was under _4_ . When MiShel became pregnant, she gave birth to a daughter. They will try to have a second daughter using the technique later this year. This is not only a _5_ effective way to select a child’s gender. It also brings a host of ethical (伦理的)and practical considerations—especially for the majority of families who use the technique for _6_ reasons. The clinic offers sex selection for two purposes: to help couples _7_ passing on a gender-linked _8_ disease and to allow those who already have a child to “balance” their family by having a baby of the opposite sex. The technology is still _9_. However, Blauer says the company has an _10_ success rate: 91 per cent of the women who become pregnant after sorting for a girl are successful, while 76 per cent who sort for a boy and get pregnant are successful.
A) genetic
B) overlapped
C) impressive
D) unaffected
E) perpetually
F) investigation
G) inquiries
H) feats
I) disorder
J) gropes
K) experimental
L) seemingly
M) elicit
N) nonmedical
O) avoid
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