1. Please describe the main features of the DNA structure. (10 points) Key features: (1) Double helical structure (4’) (2) Two strands are held together in an antiparallel orientation (3’) by base paring (1’)

Part I: Describe the following 10 terms (3 points each). (1) EF-G: a. its structure likes tRNA b. it is a translational elongation factor c. it binds to ribosome when associated with GTP

Describing the following terms (4 points each) 1. Cre recombinase 2. CSSR recombination 3. Mating-type switching 4. Mismatch repair 5. Polymerase switching 6. 30-nm fiber 7. Core histones

PART I: DESCRIPTION (2 points each) Your answer should describe what each item is and how it functions in the cell. Diagrams, structure and sequence information should be included in your answer, as necessary

How Important Is Cost? Reagents obviously figure into the cost of a procedure, but the labor required to produce and apply the reagents of purification should also be considered. How Important Is Reproducibility (Robustness) of the Procedure?

一、三种不同的RNA聚合酶 二、RNA 聚合酶的组成 三、真核RNA聚合酶的活性

一、转录反应和转录方向 二、摸板链（-）和编码链（+）p.166 三、转录步骤：起始,延伸,终止

Q1: Please name the following amino acids (three letter name, for example: Ala for alanine). Q2: Which of them are hydrophobic AA, and which are hydrophilic?

（1）开卷考试，个人独立完成 （2）不须偷看别人的答案 （3）老师宣布收试卷时，试卷必须快速由每排的最左

Quiz: Section K, L, M and N, 40 min, English answer only 1. Please list the important cis-acting elements and transacting enzymes/factors in prokaryotic transcription including initiation, elongation and termination, and briefly describe their corresponding roles (35 point)