One genetic mutationoccurs on average for every 15 cigarettes that a typical lun

One genetic mutation(基因突变)occurs on average for every 15 cigarettesthat a typical lung-cancer patient smokes, according to a study that has foundfor the first time all of the mutations happen during the lifetime of a cancerpatient.

Scientists have completed a fullgenetic examinations of the genomes（基因组） of cancer patients, and hope theinformation will lead to a basic understanding of the causes of cancer—and possibly drugs and treatments—bymaking out the mutations that turn a healthy cell into a cancerous tumor cell.

 They studied a lung-cancerpatient who had about 23,000 DNA mutations in his lung cells that wereconnected with exposure(暴露) to the toxins found incigarette smoke and had built up over his lifetime.

They also looked at a patientwith malignant melanoma(恶性黑色肿瘤), the most dangerous form ofskin cancer, who had got 30,000 special mutations known to be connected withexposure to sunlight.

Scientists believe this newfinding into the genetics of cancer will finally lead to new drugs and perfecttreatments that aim at the specific changes to the gene that cause the disease,as well as new techniques for discovering following cancers that have escapedfrom treatment in other parts of the body.

“For the first time, we have a complete map of all mutations ina cancer cell,” said Dr. Peter Campbell, who ledthe Cancer Genome project to work out the whole DNA system of tumor cells inorder find the mutations.

A similar method was performed onthe cells of a patient with skin cancer, which is how the researchers were ableto show that the malignant skin cells contained changes that resulted fromexposure to light.

“These are the two main cancers in the developed world for whichwe know the chief exposure. For lung cancer it is cigarette smoke, and formalignant melanoma it is exposure to sunlight,”Professor Campbell said.

1.What can the genetic examination of thegenomes of cancer patients be used for?

   A.To help theprofessors to win the Nobel Prizes.

   B.To advance thestudy of reason and cure of cancer.

   C.To make themedicine industries earn more money.

   D.To help the cancerpatients reduce their pain.

2.The underlined word in the third paragraphcan be placed by_____.

   A.smoke       B.sunlight     C.cell        D.poison

3.Which of the following statements is rightaccording to the passage?

   A.The lung-cancerpatient had 30,000 mutations in his lung cells.

   B.The genetics ofcancer will finally lead to new drugs soon.

   C.It’s the first time that people mapped mutations in a cancer cell.

   D.Dr. Peter tries toinvent a new drug with the DNA system.

4.What’sthe similarity between malignant melanoma and skin cancer of patients?

   A.Their smoking toomuch in daily life.

   B.Their receivingtoo much sunshine.

   C.Their refusing toaccept treatment.

  D.Their interest in travelling abroad.

试题答案

【答案】

1.B

2.D

3.C

4.B

【解析】略