This book celebrates the importance of the question; it is not meant to be a collection of facts or procedures. The writing of this book was inspired by 16 years of queries from the research community.The con￾tributors and I have tried to meet two primary objectives:

Air Buoyancy Akin to water keeping something afloat, samples can be “lifted” by air, artificially decreasing their apparent weight. This air buoy￾ancy can have a significant effect on smaller samples. Electrostatic Forces Electrostatic charges are almost always present in any environ￾ment, particularly in areas with very low humidity. If there are

troduce different notations. Some consider “NTP” a general term for deoxynucleotides, but the absence of the letter “d” indicates a ribonucleotide to others. Commercial literature also describes ribonucleotides as “RTP’s.” If the letter “d” is present, the name describes a deoxynucleotide. If “d” is absent, check the literature

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

（1）桌上只许有笔，答题纸和英文课本。（2）不许 离开自己的座位。（3）不许偷看，不许讲话 (有问题 举手）（4）老师宣布停的时候，必须放下自己的笔。 （5）老师宣布收试卷时，试卷必须快速由每排的最左 边传向右边，每排最右边的同学负责把试卷交给当堂 助教

（1）桌上只许有笔，答题纸和英文课本。（2）不许 离开自己的座位。（3）不许偷看，不许讲话 (有问题 举手）（4）老师宣布停的时候，必须放下自己的笔。 （5）老师宣布收试卷时，试卷必须快速由每排的最左 边传向右边，每排最右边的同学负责把试卷交给当堂 助教

（1）桌上只有笔和答题纸。（2）不离开自己的座位。 （3）不偷看，不讲话 (有问题举手）（4）老师宣布停 的时候，必须放下自己的笔。（5）老师宣布收试卷时， 试卷必须快速由每排的最左边传向右边，每排最右边 的同学负责把试卷交给当堂助教

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

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’)

1. What are the gene expression stages that can be regulated? (10 points) Regulated stages in gene expression: (1) transcription initiation (the most important stage): RNAP binding of the promoter, transition from the closed complex to the open complex; promoter escape 4’ (2) stages after initiation (elongation and termination) 2’ (3) RNA processing (alternative splicing) in eukaryotes 2’ (4) translation 2’