问题 单项选择题

PRPP酰胺转移酶催化()

A.PRPP生成磷酸核糖酰胺

B.IMP合成AMP

C.IMP生成GMP

D.R-5-P生成PRPP

E.甘氨酸合成嘧啶环

答案

参考答案:A

解析:考点:嘌呤核苷酸的从头合成途径。利用磷酸核糖、氨基酸、一碳单位及CO等简单物质为原料,经过一系列复杂的化学反应,合成嘌呤核苷酸的过程称为从头合成途径。特点是:在磷酸核糖的基础上逐步合成嘌呤环;生成过程:①生成次黄嘌呤核苷酸(IMP);②生成腺嘌呤核苷酸(AMP)和鸟嘌呤核苷酸(GMP),IMP是AMP和GMP的前体。重要的中间产物:①磷酸核糖焦磷酸(PRPP):由PRPP合成酶催化核糖-5′-磷酸与焦磷酸结合;②5-磷酸核糖胺(PRA):由磷酸核糖酰胺转移酶催化谷氨酰胺与PRPP反应生成。

阅读理解

Register(注册) in person

Register by phone

Register by mail

1781 N. Winchester ST.

Call 264  8833

Use form given

Chicago

Basic Photography

This is an eight-hour course for beginners who want to learn how to use a 35mm camera. The teacher will cover such areas as kinds of film, light, and lenses(镜头). Bring your own 35mm camera to the class.

Course Charge: $150

Jan. 10, 12, 17, 19, Tues. & Thurs. 6-8p.m.

Marianne Adams is a professional photographer whosephotographs appear in many magazines.

Understanding Computers

This twelve-hour course is for people who don’t know very much about computers, but who need to learn about them. You will learn what computers are, what they can and can’t do, and how to use them.

Course Charge: $75

Equipment Charge: $10

Jan. 7, 14, 21, 28, Sat. 9-12 a.m.

Joseph Saimders is a professor of computer science at New Urban University. He has over twelve years of experience in the computer field.

Stop Smoking

Do you want to stop smoking? Have you already tried to stop and failed? Now it is the time to stop smoking using the latest methods. You can stop smoking, and this twelve-hour course will help you do it.

Course Charge: $30

Jan. 4, 11, 18, 25 Mon. 4-7 p.m.

Dr.John Goode is a practicing psychologist(心理学家)who has helped hundreds of people stop smoking.

Typing

This course on weekdays is for those who want to type as well as those who want to improve their typing. You are tested in the first class and practice at one of eight different skill levels. This allows you to learn at your own speed. Each program lasts 20 hours. Bring your own paper.

Course Charge: $125

Materials Charge: $25

Two hours each evening for two weeks.

This course is taught by a number of business education teachers who have successfully taught typing courses before.

55. The word “professional” in this advertisement most probably means “_____”.

A. spiritual       B. journalist    C. professor         D. experienced 

56. The shortest course is _____.

A. Basic Photography                B. Understanding Computers

C. Stop Smoking                    D. Typing

57. There are typing courses_____.

A. on Saturdays and Sundays  B. from Monday to Friday

C. from Monday to Saturday   D. on each day in the week

58. If you can have free time only on weekends, you should take the course _________.

A. Basic Photography                B. Understanding Computers

C. Stop Smoking                    D. Typing

单项选择题 B型题