First Listening
Please listen to a short passage carefully and prepare to answer some questions.
To the naked eye the essence of life looks like water. But when it is stirred, the "water" turns out to be a sticky and thick substance, holding fast to a glass rod and forming long threads as thin as hair.
This thread of life is called DNA, which scientists have known since 1952 as the basic stuff of genetics. Now we know that human DNA functions as a biological computer program. It sends out instructions for the combining of proteins.
Scientists are making efforts to compile the first map of every detail in human DNA. What they are doing now is a biological and medical revolution. DNA in their hands has become a drug, a substance of extraordinary potential.
However, with all the frantic work being done, science is still far away from the creation of human perfection. Much more research is needed before gene therapy becomes commonplace, and many diseases will take decades to conquer, if they can be conquered at all.
Second Listening
Listen to the tape again. Then answer the following questions.
1. What does DNA look like?
2. What is the function of DNA?
3. What are scientists doing now in the research of human DNA?
