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更多“某实验室买了一批实验试剂，它们可能是做什么用的呢？请将其用途写在括号内。 Trizol试剂 （） Sanger法DNA测序 寡聚dTTP纤维素层析柱 （） 细菌总DNA提取 溴化乙锭 （） 总RNA提…”相关的问题
You are interested in cloning the maize (corn) heat shock protein into the vector pGAL. You need to choose the restriction enzymes that you will incorporate into your PCR primers and that you will use to cut the vector (pGAL) DNA. The following are maps of the multiple cloning site of pGAL and the DNA sequence that encodes the maize heat shock protein.
restriction map of the open reading frame encoding the maize (corn) heat shock protein Another student in the lab suggests that you clone the maize gene by including an XbaI site inyour forward primer and an SspI site in your reverse primer. Do you agree or disagree with this strategy? Provide two reasons for your answer.
Several lab groups independently carried out the ligation/transformation steps to join GFP gene and the pET vector. Reactions a-f were carried out in parallel. The results obtained by each of the groups were as follows:
a) Which group obtained the expected/desired pattern of results? b) Provide a likely explanation for the unexpected/undesirable results obtained by each of the other three groups. c) Calculate the transformation efficiency of AG1111 cells. Show your work.
上海应用技术大学2019—2020学年第一学期 《计算机网络原理 Computer Networks》期（末）试卷B 课程代码: B204212 学分: 3 考试时间: 100 分钟 课程序号: 1902064, 1906821，1906819, 1906824 班级： 学号： 姓名: 我已阅读了有关的考试规定和纪律要求，愿意在考试中遵守《考场规则》，如有违反将愿接受相应的处理。 题 号 一 二 三 四 五 六 七 八 九 十 总 分 应得分 10 35 55 100 实得分 试卷共 4 页，请先查看试卷有无缺页，然后答题。 I. Abbreviations: The everyday English expansions of the following abbreviations are wanted: A1-10. (1 point each, 10 points in total) A1. ICMP = A2. DNS = A3. CDMA = A4. TDM = A5. NAT = A6. VLAN = A7. CSMA/CD = A8. WAN = A9. MAC = A10. CRC =
II. Concepts: B1-7 (5 points each, 35 points in total) B1. What is the main task of the internet layer in the TCP/IP reference model respectively? What kind of protocol performs that task? B2. Please explain the differences between switches and routers. Hint you: Which layer do they work at? What kind of address do they forward data based on? B3. Why we need media access control? Please list two or more media access control methods. B4. What is the exposed station problem? Please sketch a graph to explain if necessary. B5. Besides flooding, what other routing algorithms have you learned? B6. Transport layer uses both flow control and congestion control. Please tell us what flow control is and what congestion control is? B7. What is the main difference between TCP and UDP?
III. Computation: C1-5. ( 55 points in total ). The process/procedure or explanation of computation and the correct results are all wanted. C1. (10 points) Consider building a CSMA/CD network running at 100Mbps over a 2-km cable with no repeaters. The signal speed in the cable is 20,000 km/sec. What is the minimum frame size? C2. (13 points) A bit stream 0110110 is transmitted using CRC method. The generator polynomial is x3+ x2+1. a) How many check bits should be added? b) Show the actual bit string transmitted by the sender end. c) Suppose that the second bit from the left is inverted during transmission. Show that this error will be detected by the receiver. C3. (10 points) A channel has a bit rate of 64 kbps and a propagation delay of 2 msec. For what range of frame sizes does stop-and-wait give an efficiency of at least 80 percent? C4. (12 points) A router has the following entries in its routing table: Address/Mask Next hop 130.96.39.0/24 Interface 1 130.96.39.128/25 Interface 0 130.96.40.0/25 Router 1 192.4.10.0/23 Router 2 Default Router 3 For each of the following IP addresses, what does the router do if a packet with that address arrives? Please state why you choose it. 1) 192.4.11.172 2) 130.96.39.135 3) 130.96.39.96 4) 130.96.40.168 5) 130.96.40.64 C5. (10 points) In a subnet, distance vector routing is used, and the following vectors have just come in to router D: from B: (5, 0, 8, 12, 6, 2); from C: (16, 12, 0, 6, 9, 10); and from E: (7, 6, 3, 9, 0, 4). The measured delays to B, C, and E, are 6, 8, and 5, respectively. What is D's new routing table? Give both the outgoing line to use and the expected delay.
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