9. How do mutations in the regulatory protein C affect the expression of the Ara BAD operon.
10. Present a model to explain negative control of the trp operon.
11. Present a model to explain attenuation in the trp operon.
12. Shown as the Trp attenuator in the trp operon . Refer to the drawing in order to answer the following (independent) questions (NOTE: in all cases, you must alter sequences; no deletions. You may refer to regions marked by blackballs as #1, #2, etc.) :
13. How do the following mutations in the lead peptide gene affect the expression of the trp operon. (1) AUG code into AUA。(2) Nonsense mutations in codes for trp.
14. How does antisense RNA regulate gene expression?
15. DRAW how an antisense RNA molecule would interact with an mRNA to prevent translation. LABEL the important parts.
习题十二
一、名词解释：
silencer，Cis dominance, Leu Zipper, Gene conversion, enhancer, homeotic genes, E box
二、选择题：
1. Which of the following is NOT involved in regulating the synthesis of RNA in the eukaryotic nucleus?（ ）
a). active genes in euchromatin, and inactive genes in heterochromatin;
b). amplification of some genes such as rRNA genes ;
c). use of different RNA polymerases to transcribe different classes of RNA ;
d). spliceosomes that stimulate synthesis of intron-containing hnRNAs ;
e). enhancers that can stimulate specific promoters
2. Which of the following sites may be thousands of base pairs from a promoter, yet regulate transcription? （ ）
a) Operators
b) initiators
c) enhancers
d) all of the above
e) none of the above.
3. Regulatory sequences known as enhancers: （ ）
a) Are needed for transcription by RNA polymerase III but not by RNA polymerase II
b) Encode the snRNA molecules needed for splicing RNA
c) May be located upstream or downstream of the promoter
d) Are where RNA polymerase first binds when it transcribes a gene
e) Consist of short repeated sequences of 6, 8 or 10 bases
4. When genes are regulated by steroid hormones, the steroid binds to: （ ）
a) snRNP particles in the nucleus and this promotes splicing of messenger RNA
b) Primary transcript RNA and promotes alternative splicing
c) Receptor proteins in the cytoplasm which then move into the nucleus
d) Receptor proteins in the cell membrane that pass the signal on to other proteins in the nucleus
e) A nuclear protein that binds to the CCAAT box that is found in the promoter region of some genes
5. Indicate which of the following statements are true. （ ）
a) Transcription of transferrin receptor increases when iron is in short supply.
b) Transferrin receptor protein levels increase when iron is abundant.
c) There are multiple IREs in the 3’UTR of the transferrin receptor mRNA.
d) High levels of iron remove IRE binding protein from transferrin receptor IREs.
e) Tranferrin receptor mRNA is destabilized when IRE binding protein is bound to an IRE.
6．以下对于转录因子的陈述哪两个是正确的? （ ）
a)螺旋一转角一螺旋结构域是转录激活结构域
b)转录因子的二聚化发生在碱性结构域
c)亮氨酸拉链与DNA结合
d)当来自几个转录因子的DNA结合区和激活区融合在一起时，得到功能性转录因子
是可能的
e)转录因子的同一结构域即可作为阻抑蛋白也可作为激活结构域
7．以下对于转录调控的陈述哪两个是错误的? （ ）
a)SPI含有两个激活结构域
b)类固醇激素通过与细胞表面受体结合来调节转录
c)Statla的磷酸化导致它从胞质向核内转移
d)HIV Tat调节RNA聚合酶n的磷酸化和持续合成能力
e)MyoD蛋白能和许多其他的HLH转录因子形成异源二聚体
f)同源异型框是一种保守的DNA结合结构域
8．锌指蛋白与锌的结合( )
a)是共价的
b)必须有 DNA的存在
c)通过保守的胱氨酸和组氨酸残基间协调进行
d)位于蛋白质的α—螺旋区域
9．锌指蛋白与 DNA的结合( )
a)位于 DNA大沟
b)通过“锌指”的 C端进行
C)利用蛋白的α—螺旋区域
d)每个“指”通过形成两个序列特异的DNA接触位点
e)通过“指”中保守的氨基酸同 DNA结合
10．以下关于亮氨酸拉链蛋白的叙述哪一项是正确的?( )
