3. During transcription initiation, the _____________ subunit of the RNA polymerase recognizes and binds to the -35 region of the promoter. The -10 region of the DNA, which has a consensus sequence of _______________, is then locally denatured by RNAP.
4. What regions are thought to be involved in initiation recognition in prokaryotic transcription?
5. 在RNA转录过程中
K因子的作用是 。
pho因子的作用是 。
Sigma因子的作用是 。
βˊ因子的作用是 。
NusAp因子的作用是 。
四、问答题：
1. Diagram a typical prokaryotic promoter. Exact sequences are not necessary.
2. In the DNA sequence below, put a UNDERLINE the putative -10 region, put a CIRCLE around the putative -35 region, and put a BOX around every putative start codon.
5'-ATGAATATAATTGACATATTACAATACATAATAGATCGGTATAATGCCTTGACATGCCACATG-3'
3. Draw a region of prokaryotic DNA that would be transcribed into a polycistronic mRNA and label: Promoter (P), terminator (t), open reading frame(s) (ORF), 5' flank, 3' flank, spacer (if present), RBS, ALL start and stop codons.
4. Explain the following findings: (1) E.coli core RNA polymerase transcribes intact T4 phage DNA only weakly, while holoenzyme transcribes this template very well; but(2)core polymerase can transcribe calf thymus DNA about as well as the holoenzyme can.
5. What is the probable function of this section of RNA? How does part #1 (the stem-loop) affect transcription? How does part #2 affect transcription?
6．阐述原核生物的转录终止。
(1)转录终止的两种主要的机制是什么?
(2)描述翻译怎样能调节转录终止。
(3)为什么在细菌转录终止中很少涉及到Pho因子?
(4)怎样能阻止转录的终止?
7. E.coli RNA聚合酶有哪几个亚基组成?
8. 原核生物启动子通常可分为那几个部分? 讨论突变对它们的影响。
9. 非依赖于Rho因子的终止子结构上有什么特征? 在转录终止中起什么作用?
10. Rho因子识别结合的是何种核酸分子?
习题八
一、名词解释：
UCE，Sal box，transcription factors,intitiator
二、选择题：
1. Which of the following is the main enzyme responsible for transcribing (not replicating) tRNA genes?（ ）
a) DNA polymerase I
b) DNA polymerase III
c) RNA polymerase I
d) RNA polymerase II
e) RNA polymerase III
2. All of the following can affect RNA polymerase II function except: （ ）
a) Origin of replication (ori)
b) Promoter
c) Terminator
d) Enhancer
e) Transcription factor
3. Eukaryotic promoters are composed of: （ ）
a) The initiator box, the TATA box and upstream elements.
b) The -10 and the -35 regions.
c) Introns and exons.
d) snRNPs and a complementary RNA.
e) A stem-loop structure.
4. In the following diagram of a eukaryotic gene, (B) would most likely represent：（ ）
a) Two exons that have been spliced together.
b) The enhancer.
c) The TATA box.
d) The RBS (ribosome binding site)
e) The AUG start codon.
5. Which of the following is/are not found in Class II promoters？（ ）
a）UCE；
b）CCAAT box;
c) Box C;
d). a and c;
e). all of the above (ie., none are found in Class II promoters).
6. Which of the following statements is true for the promoters of eukaryotic genes that use RNA polymerase II? （ ）
