问题 问答题 简答题

简述生物工业下游技术的特点及其重要性?

答案

参考答案:

(1)生化分离技术:是对生物界自然产生的或由微生物菌体发酵的、动植物细胞组织培养的、酶反应等各种生物工业生产过程获得的生物原料,经提取分离、加工并精制目的成分,最终使其成为产品的技术,通常也称为下游技术或下游工程。该技术是生物技术转化为生产力不可缺少的重要环节,其技术的进步程度对于保持和提高各国在生物技术领域内的经济竞争力是至关重要的。

(2)特点:生物产品包括传统的生物技术产品(如发酵生产的有机溶剂、氨基酸、抗生素、有机酸)和现代生物技术产品(如基因工程生产的疫苗、干扰素、活性肽等)。它们的生产不同于一般的化学品,有其自身的特点:

A:发酵液或培养液中欲提取的生物物质浓度很低

B:培养液是多组分混合物

C:生化物质稳定性差

D:发酵或培养大多是分批操作

E:对最终产品的质量要求很高

(3)重要性:

A:生化分离技术是生物产品工业化的必要手段,具有不可取代的地位。生物产品一般是从各种杂质中制备的,只有经过分离和纯化等下游加工过程才能制得符合使用要求的高纯度产品。

B:生化分离的实施十分艰难且需要很大代价。特稀的水溶液原料和高纯度产物之间的巨大差异造成的。产物稳定性差,导致起回收率不高,如抗生素产品一般要损失20%左右。

C:分离纯化的方法十分复杂和昂贵,产品成本中,分离与纯化部分占总成本的40-80%,精细、药用产品更高;生产过程中,下游加工的人力、物力占全过程的70%-90%。

填空题

Part 1


·Read the article below and choose the best sentence from the list on the next page to fill each of the gaps.
·For each gap (1-8) mark one letter (A-H) on the Answer Sheet.
·Do not mark any letter twice.

When the Young Take Their Lives


A few weeks ago, I received a particularly disturbing page. "A 22-year-old woman is in the emergency room with a gunshot wound to the head," my chief resident told me. (1) . The woman, a recent college graduate, was starting to show signs of brain death. Over the next several hours, we worked to preserve the life she had tried to throw away.
(2) . In the 30 years from 1950 to 1980, the annual suicide rate among college-age women has almost doubled, from 3.9 deaths per 100,000 to 7.0 per 100,000, while the rate among college-age men has tripled, from 10 per 100,000 to 32 per 100,000 a year. (3) .
Students kill themselves at all times of year, but attempted suicides begin to go up in the fall, according to the National Institute of Mental Health. Often the immediate cause seems to be a recent rejection, disappointment or academic failure.
(4) . Even trained mental-health professionals have made mistakes. But there are warning signs you can watch for in friends and loved ones, such as withdrawing from all social activities, dramatic changes in personality—including suddenly becoming much happier or calmer-significant shifts in sleeping or eating habits and giving away cherished personal items.
(5) . Studies of suicide survivors show that often just five minutes elapse from the time someone thinks about committing suicide until the actual attempt.
Finally, it is OK to come right out and ask friends or family members whether they are thinking of suicide. (6) . Be sure to let them know that they are not alone and that help is available through school counselors and mental-health hot lines, in hospitals and now online.
Through the years, I have treated many patients who have attempted suicide. (7) . Our 22-year-old patient is awake now and even talking a bit. I’m optimistic about her physical recovery but disquieted about her chances overall. (8) . What no one knows is whether we will be able to pick up the pieces one more time.
  • A. I do it with the sincere hope that they will get better
  • B. "Oh, and it looks self-inflicted," he added
  • C. The experts will tell you that having tried to kill herself once, she is at a greater risk of trying again
  • D. This year’s toll for adults aged 19 to 24 is expected to reach 1,000 deaths
  • E. Don’t get fooled into thinking that all people who commit suicide have carefully worked out a plan in advance
  • F. You won’t be giving them any ideas
  • G. Trying to determine whether a young person is suicidal can be difficult
  • H. Her predicament made me wonder, once again, what drives people to suicide and why young people resort to such a desperate measure

多项选择题