Chapter 12 Gene Regulation in Prokaryotes
Part 1
1. The lac repressor is a ___
(1)DNA molecule.
(2)lipid molecule.
(3)carbohydrate.
(4)RNA molecule.
(5)protein molecule.
2. What would be the effect of a mutation in the operator that blocked the lac repressor binding?
(1)The genes would be inducible by lactose.
(2)The lacZYA genes would be expressed constitutively.
(3)The lacZYA genes would not be expressed
(4)The lacZYA genes would be repressed by lactose
(5)None of the above.
3. What would be the effect of a mutation in the lacI gene that blocked binding of the lac repressor to the operator?
(1)The lacZYA genes would be expressed constitutively
(2)The lacZYA genes would be repressed by lactose.
(3)The lacZYA genes would not be expressed.
(4)The genes would be inducible by lactose.
(5)None of the above
4. Which of the following are examples of cis acting genes
(1)LacP, lacO
(2)lacI, lacZ
(3)lacY, lacZ, lacA
(4)lacI, lacY, lacZ
(5)lacI
5. A regulatory site within the leader sequence of the tryptophan operon that controls this operon by diminishing transcription is called
(1)Transcriptor
(2)Attenuator
(3)Repressor
(4)Operator
(5)upregulator
6. In the absence of tryptophan:
(1)The repressor binds to the co-repressor. Transcription is initiated.
(2)The repressor is inactive and does not bind to the promoter. Transcription is initiated.
(3)The trp operon is repressed and transcription occurs.
(4)The repressor is active and does not bind to the promoter. Transcription does not occur.
7. In the lac and trp operators, the repressor is said to be an allosteric molecule because:
(1)It represses the production of lactose or tryptophan.
(2)It induces the production of lactose or tryptophan.
(3)Interaction with another molecule causes a conformational change in the repressor's active site
(4)It induces the production of lactose or tryptophan.
(5)It diminishes the transcription of the related gene structure.
8. When glucose is present:
(1)cyclic AMP is high, the catabolite activator protein (CAP) binds to the activator binding site, and
transcription of lactose is turned on
(2)cyclic AMP is low, CAP binds to the site activator binding site, and transcription of lactose is turned
on
(3)cyclic AMP is high, CAP does not bind to the activator binding site, and transcription of lactose is
turned on
(4)cyclic AMP is low, CAP does not bind to the activator binding site, and transcription is turned off
9. The lac repressor
(1)binds to the operator and prevents transcription
(2)binds to the CAP site and prevents transcription
(3)binds to the operator and facilitates transcription
(4)binds to the CAP site and facilitates transcription
10. When both glucose and lactose are present
(1)cyclic AMP is high so transcription occurs
(2)the lac repressor binds with the lactose and transcription occurs
(3)RNA polymerase is able to bind to the operator so transcription occurs
(4)transcription is turned off
11. The operator is
(1)another name for the terminator of a gene
(2) a DNA site bound by repressor proteins
(3) a protein that coordinates gene expression
12. ___binds to the repressor and turn on the transcription of the structural genes in the Lac operon.
(1)cAMP
(2)lactose
(3)allolactose
(4)CRP
13. If a normal (wild type) repressor is added in vitro, which DNA fails to bind the repressor?
(1)I+ O+ Z+
(2)I+ Oc Z+
(3)I+O+ Z+
(4)I+ O+ Z-
(5)All of the above will bind the repressor
Part 2 Ture or false
1. In the absence of glucose, when lactose is present it combines with the repressor, allowing RNA polymerase to carry on transcription. ( )
2. When both glucose and lactose are absent, transcription occurs.( )
Part 3 question
How does an extracellular signal control its target gene expression by modulating the activity of a transcriptional regulator?
What are the general principles of transcription of regulation in both prokaryotic and eukaryotic cells?
A bacterium is found to metabolize a rare sugar produced by a plant that the bacteria grow on. However, the bacteria prefer glucose as the energy source. The problem is, if you want to finish this course with a satisfied score, you must figure out the regulatory mechanism that the bacteria used to determine the sugar choice.
The gene involving in the rare sugar metabolism has been identified as fun3. You can use northern blot to analyze the expression of fun3 and use DNA footprinting to analyze the binding of proteins to the control elements of fun3 gene. The following table shows the experimental results
Questions:
1.Please propose a mechanism to explain the above results. You should focus on the question “How does the
expression of fun3 gene is tightly regulated so that it is only highly expressed when the rare sugar is the only carbon source”. You must answer what p roteins A, B and C are.
2.How is protein A regulated?
(1)glucose turns the repressor on
(2)glucose turns the repressor off
(3)the rare sugar turns the repressor on
(4)the rare sugar turns the repressor off
3.How is protein C regulated?
(1)glucose turns the activator on
(2)glucose turns the activator off
(3)the rare sugar turns the activator on
(4)the rare sugar turns the activator off
4.How could you make the bacteria always use the rare sugar as the energy source even in the presence of
glucose?
The simplest way: Change the promoter of fun3 gene to a strong promoter containing all the consensus sequence. Thus, fun3 gene is always highly expressed when rare sugar exists.
5. Use one example to illustrate that bacterial gene regulation can occur at and after the transcription initiation.
Part 4
MODEL 1:
Model 1 below shows the promoter of a regulated gene in E. coli. The promoter region of the lac operon (DNA depicted below) is shown under four different growth conditions and the resulting effects on transcription are reported.
Use this model to answer questions 1-5 about how the genes in the lac operon are regulated.
1. a. Which transcriptional regulator helps activate transcription? ________
b. Which transcription regulator represses (blocks) transcription? ________
2. Suggest a molecular explanation for why transcription rates are relatively low in condition A, but nowhere near as high as when only lactose is present as a carbon source. Why might this be? (Hint: Think along the lines of RNA polymerase binding the promoter).
3. For effective regulation of the operon, should the transcription regulators have specific DNA sequences that they can bind, or should they be able to bind any sequence of DNA? Explain your rationale.
4. Would transcription regulator X work as efficiently if it bound where Y does? Vice versa?
5. a. One gene in the lac operon encodes the -galactosidase enzyme which breaks the disaccharide lactose down into the monosaccharides glucose and galactose. The regulation of the lac operon depends on the whether the cells are grown on media containg lactose or glucose . Why is this logical?
b. Which transcription regulator is responding to the presence of glucose? _____
How do you know?
c. Which transcription regulator is responding to the presence of lactose? _____
How do you know?
MODEL 2:
Transcription regulators X and Y both
have two mutually distinct conformations
based on the binding of a small molecule:
6. a. In which state does X bind to DNA?
(highlight the correct answer)
- when cAMP is bound
- when cAMP is not bound
b. What is the relationship between glucose levels and cAMP levels in a cell, based on Models 1 and 2?
7. a. In what state does Y bind to DNA?
(highlight the correct answer)
- when lactose is bound
- when lactose is not bound
b. Explain how Y's response to lactose is logical given how Y regulates the production of the enzyme
-galactosidase.
8. X and Y proteins are encoded by their own genes elsewhere on the E. coli chromosome. For effective regulation, should the X and Y genes be constitutively expressed (always on) or regulated? Explain.
9. Imagine that the gene coding for regulator Y was mutated so that the Y protein's DNA binding site was deleted completely. Estimate B-galactosidase enzyme production for each scenario in Model 1 for this mutant.
A: _____________ B: ___________ C: ___________ D: ________
新编语言学教程Chapter 12答案 Applied Linguistics 1. Define the following terms briefly. (1) applied linguistics: the study of language and linguistics in relation to practical issues, e.g. speech therapy, language teaching, testing, and translation. More often than not nowadays, it is used in the narrow sense, and refers to language teaching in particular. (2) grammar-translation method: a method of foreign or second language teaching which makes use of translation and grammar study as the main teaching and learning activities. (3) audiolingual method: the teaching of a second language through imitation, repetition, and reinforcement. It emphasizes the teaching of speaking and listening before reading and writing and the use of mother tongue in the classroom is not allowed. (4) communicative language teaching: an approach to foreign or second language teaching which emphasizes that the goal of language learning is to achieve communicative competence.
第十二章 奶油和涂布乳制品 国际乳品协会（IDF）介绍了一种包括奶油和涂沫制品的标准，即IDF标准166： 1993，“涂布脂肪指南”，这些指南的意图是用来提供一个主要框架，在该框 架下不同国家可以根据自身需要设定更加明确详细的一组或单一的标准。
定义 涂布脂肪：“涂布脂肪”是一种以乳浊液形式存在的食物，主要是油包水型，并且主要由水相、食用脂肪和油组成。 食用脂肪和油主要由脂肪酸的甘油三酸脂组成，它们来源于蔬菜、动物、乳或海产品。 下列表(12.1和12.2)选自于该标准。 表12.1 乳脂肪和人造奶油制品的主要组成 乳脂产品 混合脂肪产品 人造奶油产品 总脂肪中含乳 总脂肪中乳脂含量 总脂肪中乳脂含量 脂100% 最高为80%，最低为15% 最高为3% 注意，按照一些国家的或其它的有关法规：脂肪含量和乳脂与其它种类脂肪的比例会有一些更严格的限制性范围。 主要的原料应该是水和/或乳制品，食用脂肪和/或油或者是它们的混合物，关于脂肪含量及涂布脂肪的标准可依据脂肪的来源不同分为三类，最高脂肪含量应达到95%。 食物的名称应符合国家法规的规定，但产品需遵守表12.2所列的一般要求，该表将所有产品全部覆盖在以下三大类中： 表12.2 乳脂肪和人造奶油制品的名称 脂肪含量% 乳脂产品 混合脂肪产品 人造奶油产品 80-95 奶油 混合物 人造奶油 762-<80 涂布乳品 涂布混合物 涂布脂肪 60-62 3/4脂肪或 3/4脂肪或 3/4稀释脂肪 稀释脂肪 稀释脂肪 稀释脂肪 奶油 混合物 人造奶油 <41-<60 减量脂肪 减量脂肪 减量脂肪涂布 涂布乳品 涂布混合物 涂布 39-41 1/2或低脂奶油 1/2或低脂混合物 1/2或低脂人造 奶油或米纳林 <39 涂布低脂肪乳品 涂布低脂肪混合物 涂布低脂肪 下列联合国粮农组织/世界卫生组织(FAO/WHO)的标准普遍适用于在国际贸易中并指明所允许使用的产品的名称： A1－奶油和乳清奶油标准 （A16－涂布低脂乳品标准——草稿） 规范标准32-1981是人造奶油标准 规范标准13-1981是低脂奶油标准
Chapter Quiz 12 1._____ theories of leadership focus on personal qualities and characteristics. A.Trait B.Path-goal C.LPC D.Contingency 2._____ is the extent to which a person is likely to have job relationships that are characterized by mutual trust, respect for employees' ideas, and regard for their feelings. A.conscientiousness B.emotional stability C.courage D.consideration 3.According to Fiedler's contingency theory, if there is NOT a match of leadership style to the group situation, what should be done? A.Replace the manager. B.Change the situation to fit the leader. C.Both A and B. D.None of the above. 4.Situational leadership theory (SLT) differs from other leadership theories most clearly because it _____. A.identifies specific leadership styles B.focuses on the followers C.makes leadership contingent on the situation https://www.doczj.com/doc/e16551361.html,es the leadership dimensions of task and relationship behaviors 5.A _____ leadership style, identified by House in path-goal theory, leads to greater satisfaction when tasks are ambiguous or stressful than when they are highly structured and well laid out. A.directive B.supportive C.participative D.achievement-oriented 6.Which of the following is NOT true of charismatic leaders? A.They have a vision. B.They have behavior that is unconventional. C.They are willing to take high personal risk. D.They are focused on their personal needs. 7.A charismatic leader's _____ is key to follower acceptance. A.energy B.vision C.credentials D.history with the organization 8.The overall evidence indicates that transformational leadership is more strongly correlated than transactional leadership with _____. A.lower turnover rates B.higher productivity C.higher employee satisfaction D.all of the above 9._____ leaders know who they are, know what they believe in and value, and act on those values and beliefs openly and candidly. A.Transformational B.Transactional C.Charismatic D.Authentic
第十二章 卷积码的概率译码 习题 1．已知（3，1，2）码的G (D)=[1+D 2，1+D+D 2，1+D+D 2]， （1）对长为L=4的信息序列画出篱笆图； （2）求与信道序列M =（101100）相应的码字； （3）用硬判决VB 译码器译接收序列R =（111，111，000，100，000，111）。 2．第1题中的码字通过二进制输入、八电平均匀量化输出的DMC 后，得到的接收序列R = （764，565，032，530，311，477），利用最小软距离译码准则，应用软判决VB 译码器，译该接收序列。 3．找出当C 1=1，C 2=10时图12-5DMC 的整数度量表。应用这个整数度量表，用VB 译码器 译接收序列：R =（111112，121112，010202，120201，020101，121111） 。 4．若用表12-1（b ）的整数度量表，求用VB 译码器译第3题中的接收序列，并与第3题和 第2题的结果进行比较。 5．考虑一个二进制输入、八进制输出的DMC ，有转移概率如下： (|)i i P r c 6．一个生成矩阵 G (D)=[1+D 2+D 3，1+D+D 2+D 3] 的（2，1，3）码， （1）画出L=4的篱笆图； （2）设一个码组在题5中所述的DMC 传输，它的接收序列：R =（1211，1201，0301，0103， 1202，0311，0302） 。试用VB 译码器求出此码序列。 7．考虑习题6的（2，1，3）码，画出L=4的码树图。设计一个转移概率p=0.045的BSC ； （1）求出该信道的FA 比特度量表和整数度量表； （2）利用FA 算法译接收序列：R =（11，00，11，00，01，10，11）。 8．计算第5题中信道的FA 比特度量表和整数度量表。 9．利用ST 算法译第7题中的接收序列。 （1）利用第7题的FA 整数度量表； （2）利用第8题的FA 整数度量表。 10．对第5题中的DMC 信道计算R comp 1
Chapter 12 job hunting 课文语言点 1，make mistakes 意为“犯错，出错”= make a mistake make mistakes in ... 意为“在某方面犯错误” Did you make mistakes again ？你又犯错误了吗? I made a mistake in spelling 我犯了一个拼写错误 by mistake 错误地I took your book by mistake 我错拿了你的书 mistake 还可作动词,意为“弄错，误解”mistake ...for 意为“把...错认为...” she is often mistaken for a teacher 她经常被误认为是个老师 2,hunt vi 意为“搜寻，寻找”常与for 构成短语hunt for ，意为“寻找，搜寻” He has hunted everywhere for his key 。他处找他的钥匙 She began to hunt for a job after she left school 她毕业后就开始找工作 3，application 名词，意为“申请，请求” He sent in his application to the company 他向公司提交了申请书。 make an application for = apply for “申请” Who will make an application for the job ？= who will apply for the job ？ 谁会申请这份工作？ 4，interview v/ n 面试，采访do an interview “采访” The boss interviewed the person who applied for the job 老板面试了这个求职的人 interviewee n 被面试者雇员interviewer n 面试者，雇主 5，require vt 意为“需要，要求”后跟名词、代词作宾语。 The work requires care and patience 这工作需要细心和耐心。 require sb to do sth 要求某人做某事 He required us to be quiet 他要求我们安静 require doing sth 意为“需要（被）... 表示被动意思” Plants require watering regularly 植物需要定期浇水 6, as well as 意为“还有,而且” 可以用来连接两个相同的成分，如名词、形容词、动词、介词等。通常不位于句首。as well as 连接的虽然是两个并列成分，但强调的重点在前面，不在后面，意为“不但。。。而且”，翻译时要先译后面的，再译前面的，如 Living things need air and light as well as water 生物不仅需要水，还需要空气和阳光 She continued her own work as well as helped me 她除了帮助我，还继续自己的工作 The child is lively as well as healthy 这孩子既健康又活泼 拓展： 1，as well as 用于同等比较，表示“和...做得一样好” She tries to learn painting as well as her deskmate He can do everything as well as his brother 2, as well as 还可表示“除。。。这外”= besides Hiking is good exercise as well as fun 徒步旅行除了有趣以外，还是很好的锻炼 区别：as well as 和not only ...but also意为“不但...而且” as well as 强调as well as之前的部分,属插入语,谓语要与它前面的主语保持人称和数一致not only ...but also 强调.but also之后的部分,谓语要与靠近它的主语保持人称和数的一致. He as well as I likes the job 不仅我,而且他也喜欢这份工作.