问题 问答题 简答题

试述T细胞的主要表面分子及其特征。

答案

参考答案:

T细胞的主要表面分子有:①T细胞抗原受体(TCR),可表达所有成熟T细胞表面是T细胞识别蛋白质抗原的特异性受体;②CD3分子表达于全部T细胞表面可与TCR分子以非共价结合形成一个TCR-CD3复合受体分子,具有稳定TCR结构和传递活化信号的作用;③CD4和CD8分子,是细胞与细胞之间相互作用的粘附分子;④CD28分子,为最重要的协同刺激受体分子;⑤CD2分子,是细胞间粘附分子,也是信号传导分子,可使T细胞活化,它不依赖于TCR途径,是T细胞活化的第二途径;⑥极迟活化分子(VLA),可与细胞外基质配体分子相结合,为T细胞活化提供协同刺激信号;⑦细胞因子受体;⑧CD44和CD45分子,CD44分子为一种归巢受体,CD45对各种活化途径有重要调节作用。

完形填空

On Thursday afternoon Mrs Clake locked the door and went to the women’s club as usual. It was a pleasant way of ___1___ time for an old woman who lived ___2___.

When she came home she ___3___ something unusual. Had someone got in? The back door and the windows were all locked and there was no ___4___ of forced entry(进入). Had anything been taken? She went from room to room, ___5___, and found her camera and spare watch missing.

The following Thursday she went out at her ___6___ time, but didn’t go to the club. Instead, she took a short walk in a park ___7___ and came home, letting herself in through the ___8___ door. She settled down to wait and see what would happen.

It was 4 o’clock when the front doorbell rang. Mrs Clarke was ___9___ tea at the time. The bell rang again, and the next moment she ___10___ her letter-box being pushed open. Picking up the kettle of boiling water, she moved ___11___ towards the letter-box. A piece of ___12___ appeared through the letter-box, and then a hand. The wire turned and caught around the knob(原形旋钮) on the door-lock. Mrs Clarke ___13___ the kettle and poured the water over the hand. A ___14___ cry was heard outside as the wire ___15___ to the floor and the hand was pulled ___16___, which was followed by the sound of ___17___ feet.

It wasn’t long ___18___the police caught the thief. And Mrs Clarke was greatly ___19___ at the club for her successful ___20___.

1. A. saving         B. passing        C. stealing         D. finding

2. A. lonely          B. alone           C. sadly            D. easily

3. A. learned        B. found          C. sensed          D. hoped

4. A. sight            B. exhibition        C. note                 D. sign

5. A. watching            B. searching            C. looking         D. checking

6. A. late          B. dinner          C. usual            D. own

7. A. faraway       B. club           C. nearby          D. hurriedly

8. A. open            B. back            C. front            D. broken

9. A. drinking       B. making        C. pouring         D. planting

10. A. saw           B. watched       C. heard            D. smelled

11. A. quietly        B. loudly          C. fast            D. angrily

12. A. wood         B. equipment       C. chalk            D. wire

13. A. discovered    B. brought        C. raised           D. supported

14. A. soft           B. gentle           C. sharp          D. loud

15. A. pushed       B. put            C. stuck          D. fell

16. A. up           B. forward        C. back           D. down

17. A. walking       B. jumping        C. running        D. steady

18. A. after          B. when           C. before         D. until

19. A. admired      B. encouraged       C. instructed       D. supported

20. A. self-satisfaction B. self-protection      C. self-respect         D. self-service

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