问题 问答题

粘附分子可分为哪几类,主要有哪些功能

答案

参考答案:

解析:粘附分子根据其结构特点和功能可分为整合素家族、免疫球蛋白超家族、选择素家族、钙粘蛋白家族等。 整合素家族主要介导细胞与ECM粘附,以及白细胞与血管内皮细胞黏附;免疫球蛋白超家族是指具有与IgV或C区相似的折叠结构,且氨基酸组成有一定同源性的一组分子,包括粘附分子、MHC、抗原识别受体、IgFc受体、白细胞分化抗原等,其主要功能是参与细胞间相互识别和相互作用;选择素家族主要介导血液流动状态下白细胞与血管内皮细胞的局部黏附;钙粘蛋白家族主要在细胞生长发育的选择性聚集中发挥重要作用。 粘附分子的生物学功能主要包括有 (1)作为辅助受体和协同刺激分子,参与免疫细胞识别与激活。 (2)参与炎症过程中白细胞与血管内皮细胞粘附。 (3)参与淋巴细胞的归巢。

阅读理解

阅读理解。

     A wellmade film offers a whole world of things to watch. First there are the story aspects-the plot,

characters, dialogue and themes. Then there are the technical aspects-the camera work, cuttings and

special effects. And there are many other things, like the credits, musical score and the acting. A

wellmade film offers much more than you see in one viewing.

     Films are a means of communication. They can tell you things, just as newspapers do, or television,

or any other means of communication. Sometimes they communicate important things to you, like ideas

or lifestyles or ways of looking at the world. Sometimes people are aware of this, and sometimes not.

The more you are aware of this,the better you are.

     Notice, for example, the way films sometimes affect fashion. A star dresses or wears her hair in a

certain way, and suddenly everyone is imitating her. Boys in the 1950s could sometimes be seen wearing

black leather jackets, idling (闲逛) on street corners and smoking cigarettes. They were imitating

Marion Brando. His films taught them a certain way to behave.

     Films can also teach politics. In Star Wars, the heroes were a bunch of lovable incompetents fighting

with guts (胆量) and not much else. They were, in fact, rather like the British in the early days of WW?

. Their  enemies, like the Nazis, had a big advantage in equipment and numbers of troops, and they were

like the Nazis in discipline and heartlessness too. The whole film, in fact, was a rerun of WW?, and taught values like faith and love of liberty. This is all to the good, but the point is, did you notice it?

1. All of the following are mentioned as noticeable   aspects of a film EXCEPT________.

A. the list of names of actors and directors, etc.

B. the cost of a film

C. the music for a film

D. the language used in a film

2.The last sentence in Paragraph 1 probably means ________.

A. a high quality film can be appreciated repeatedly  from different angles

B. a good film always attracts a lot of viewers

C. a wellmade film usually has more than one theme

D. one can never find out how many characters there    are in a good film

3. It can be inferred from the passage that in his film, Marion Brando was ________.

A. a motorist who always wore a black leather jacket

B. a homeless man who died of excessive smoking

C. a rebellious man during WW ?

D. an idler who didn't have any serious things to do

4. Star Wars is a film________.

A. about WW ?  

B. for politics

C. reflecting WW ?  

D. for peace lovers

单项选择题 A1/A2型题