物化心得

物化心得（精选4篇）

物化心得 篇1

应化111

23211111

李彪

时光荏苒，白驹过隙，转眼间，大二的上学期即将要过去。然而，在短短的几个月里面依旧有值得我们回味的东西。每学期我们都有一个化学实验课程，这学期就是物理化学实验。

理论指导实践

这学期的物理化学实验放在周四的下午，而且是隔一周一次，这就让我们有时间先把理论学习好，再来实践，便是用理论指导实践。不得不说，物理化学的理论性非常强，需要我们有较强的逻辑思维能力和把之前所学知识融会贯通的能力。所以，物理化学对我个人来说是一门有挑战性的课程。正因为物理化学有较强的理论性，所以物理化学实验的运用就很有必要。通过物理化学实验，我们能通过具体的运用所学理论知识来解决实际问题，从而来更好的体会和理解理论的精髓所在。在学测定物质的燃烧热时，我们实验所测量的是在等容条件下的燃烧热，而平时大家所常用的是等压下的燃烧热。通过实验，我们可以了解到等容的条件是比等压容易达到的，再利用等容燃烧热和等压燃烧热的关系便可以求得等压下的燃烧热。同样这个实验，我们利用一个大的桶形容器装满水，在把氧弹放入桶中，而且在底座还放了特殊材料的隔热底盘，从而把桶和水作为环境。这一做法其实也是觉得实验很精妙和严谨的地方，同时也让我对环境和体系之间的关系、区别以及转换有了更加深刻的理解。

团队协作

物理化学实验和以往的无机实验或是分析实验的区别在于以小组为单位，我们做实验时，往往是四人一小组（也有八人小组实验，不过次数就一二次）。四个人做一个实验，需要的不仅仅是个人的化学能力，还有协作能力。只有具备这两项，小组实验才能又好又快的完成。小组实验里面比较重要的工作就是分工。在做分光光度法测定平衡常数时，往往要配十几瓶溶液，而且需要准确配制。一个人根本不可能在短时间内完成这项工作。而小组如果能把工作分配好，以流水线式配制溶液，准确度高，而且速度还快，并且可以体会到集体完成一个较繁琐工作时的成就感。对我们大家以后的实验或者是工作都有很大的帮助。

严谨治学

物理化学实验虽然在理论的指导下进行实验，但因为种种原因有很多不能客服的误差，甚至有些误差比较大（当然也有我们自身的实验错误）。这时，我们便要耐下心来认真分析实验存在误差的原因和问题。有时候计算出的数据和实际结果差距很大，但依旧要在实验报告中将其如实的写出，分析出相应的原因。我觉得这不仅是对实验负责，更是教我们有一种实事求是的精神。

激发兴趣

物理化学实验经常要用到物理的一些方法来研究或是做实验。这时，自然而然要用到一些仪器。在物理化学实验中，我第一次接触到氧弹和第一次往氧弹里充气放气，第一次用压片机压片……这些都很新奇，亲手试试后确实很开心，让我对物理化学实验充满了兴趣。这也让我对以后的实验都充满了期待。

物化实验总结 篇2

姓 名：

学 号：

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年 级：

专 业：

物理化学实验是师专化学学科的一门必修基础实验课程。它以测量数据为主要内容，研究物质的物理化学性质及其化学反应规律。它综合了化学学科各领域所需要的基本研究工具和方法。

物理化学实验可以培养我们初步掌握物理化学的实验方法，训练我们掌握基本的物理化学实验技术，并加深对物理化学中某些理论和概念的理解。它对培养我们观察、思维、动手能力起着重要作用，也对先行课程的基本实验技术的训练是一个巩固、熟练和提高。

这学期我们的实验也都结束了，其中学到了不少知识，也遇到了不少问题，这里我就对我们之前做的十个实验进行一一总结一下。实验一：二组分金属相图的绘制 操作要点：

（1）对样品加热温度不能太高，温度太高样品易氧化变质，步冷曲线可能出现转折；

（2）冷却过程中应该注意经常轻微转动装有热电偶的玻璃套管，并且热电偶热端应插到样品中心部位，使样品受到轻微搅拌以防止产生过冷现象，保证实验精度；

（3）混合物的体积有两个转折点，必须待第二个转折点测完后方可停止实验，否则需重新测定；

（4）实验使用电位差计连续测量时，要经常核对工作电流，以保证实验精度；（5）实验过程中要注意检查保温杯内的冰水，必须保持冰水共存，以保证热电偶测量结果的可靠性；

（6）某些体系在析出固体时，会出现“过冷”现象，即温度达到凝固点是不发生结晶，当温度达到凝固点一下几度时才出现结晶，出现结晶后，体系的温度又回到凝固点。在绘制步冷曲线时，会出现一个下凹。在确定凝固点温度时，应以折线或平台作趋势线，获得较为合理的凝固点。实验改进及其建议：

（1）本实验所用体系为Sn-Pb低熔点金属体系，但它的蒸汽对人体健康有危害，因而要在样品上方覆盖石墨粉或石蜡油，防止样品的挥发和氧化。石蜡油的沸点较低（大约300℃），故加热过程温度不宜过高，特别是样品近融化时所加电压不宜过大，以防止石蜡油的挥发和碳化。

（2）由于实验步骤繁琐，耗时过长，我们可选用可控升降温电炉，在保证实验效果的同时，简化了步骤。实验二：纯液体饱和蒸汽压的测定 操作要点：

（1）测定系统不能漏气时本实验成功的前提条件之一，实验装置所有玻璃活塞均要用真空脂封旋紧，用于连接的橡胶管都应完好不漏气，无老化现象；（2）真空泵与系统相通时，抽气不可太快，否则会使封闭液迅速蒸发，不能顺利冷凝回流，封闭液迅速减少以致消失而使实验难以进行；

（3）开动真空泵前必须先接通冷凝水，以保证已蒸发的乙醇冷凝回流至封闭液处；

（4）蒸汽压与温度有关，故测定过程中恒温槽的温度波动需控制在正负0.1K以内；

（5）实验过程中调节液面等位时需防止B管液体及空气倒灌。一旦倒灌带入空气，必须补足B管内液体并从排空气步骤重新做起；

（6）抽空气的速度要合适。必须防止等位计内液体沸腾过剧，以免使B管内液体被抽尽。实验讨论：

1、影响实验成败的几个关键因素：（1）实验装置密封性的好坏；（2）是否能适时调节真空泵的抽气速度；（3）实验过程中冷凝水的作用是使被抽出的乙醇蒸汽不断冷却回流补充封闭液。

2、影响实验精确度，作图时线性不佳的主要因素：（1）温度波动误差的影响；（2）初始测量时，A、B管间空气未能驱尽；（3）等压计固定的位置不垂直读书时会产生误差。

测定液体饱和蒸汽压的其他方法介绍：

（1）动态法。当液体的蒸汽压与外界压力相等时，液体就会沸腾，沸腾时的温度就是液体的沸点。即与沸点所对应的外界压力就是液体的蒸汽压。若在不同的外压下，测定液体的沸点，从而得到液体在不同温度下的饱和蒸汽压，叫做动态法。该装置较简单，只需将一个带冷凝管的烧瓶与压力计及抽气系统连接起来即可。实验时，先将体系抽气至一定的真空度，测定此压力下液体的沸点，然后逐次往系统放进空气，增加外界压力，并测定其相应的沸点。只要仪器能承受一定的正压而不冲出，动态法也可用以101.325KPa以上压力的实验。动态法较适用于高沸点液体蒸汽压的测定。

（2）饱和气流法。在一定的温度和压力下，让一定体积的空气或惰性气体以缓慢的速率通过一个易挥发的待测液体，使气体被测液体的蒸汽所饱和。分析混合气体中各组分的量以及总压，在按照道尔顿分压定律求算混合气体中蒸汽的分压，即是该液体在此温度下的蒸汽压。此法一般适用于蒸汽比较小的液体。该法的缺点是：不易获得真正的饱和状态，导致实验值偏低。

所以比较而言静态法适用于固体加热分解平衡压力的测量和易挥发液体饱和蒸汽压的测量，准确性较高。实验三：完全互溶双液系的平衡相图 实验操作要点：

（1）沸点仪中没有装入溶液之前绝不能通电加热，如果没有溶液，通电加热丝后沸点仪会炸裂；

（2）一定要在停止通电加热之后，方可取样进行分析；

（3）沸点仪中蒸汽的分馏作用会影响气相的平衡组成，使得气相样品的组成与气相平衡时气相的组成产生偏差，因此要减少气相的分馏作用；

（4）使用阿贝折光仪时，棱镜上不能触及硬物（滴管），每次加样前，必须先将折射仪的棱镜面洗净，可用数滴挥发性溶剂（如丙酮）洗涤，在用擦镜纸轻轻吸去残留在在棱镜面上的溶剂。在使用完毕后，也必须将阿贝折射仪的棱镜面处理干净；

（5）测定折光率时速度要快，以避免样品中易挥发组分损失，以确保数据准确；（6）每次取样量不宜过多，取样管一定要干燥，不能留有上次的残液，气相部分的样品要取干净。

实验四：凝固点降低法测定摩尔质量 操作要点：（1）每次测定应按要求的速度搅拌，并且测溶剂与溶液凝固点时，搅拌条件要完全一致，读取温度应准确到小数点后第二位；

（2）寒剂温度对实验结果也有很大的影响，过高会冷却太慢，过低则测不出正确的凝固点；

（3）纯水过冷温度约为0.1-1℃（视搅拌快慢），为了减少过冷温度，可以加入少量的晶种，每次加入晶种大小应尽量保持目的；（4）高温、高湿季节不宜安排本实验。实验讨论：

（1）“凝固点降低法测定摩尔质量”是一种比较简便和准确的测量溶质摩尔质量的方法，而且在溶液热力学研究和实际应用上都有重要的意义。

（2）为了获得比较准确的摩尔质量数据，常用外推法，即以所测的摩尔质量为纵坐标，以溶液浓度为横坐标，外推至溶液浓度为零，从而获得比较准确的摩尔质量值。

（3）本实验测量的成败关键是控制过冷程度和搅拌速度。实验改进：

在橡胶塞上钻一个小孔，穿入细铁丝，铁丝的下端系上经过小孔可以上下提拉的宽5mm，长2cm的小铜片，当发生过冷时把小铜片伸入溶液中，铜的导热性好，在精确测定水的凝固点过程中，在粗测以下0.2℃开始搅拌同时放入铜片，铜片迅速吸热降温，周围水的温度回升，打破过冷水的亚稳状态，水中固体析出。实验五：电极的制备和原电池电动势的测定 操作要点：

（1）铜电极电镀前应认真处理表面，将其表面用新的金相砂纸磨光，须做到平整光亮；电镀好的铜极不宜在空气中暴露时间过长，防止镀层氧化，应尽快洗净并置于电极管内的溶液中，放置半小时，待其建立平衡，再进行测量；（2）组成电池的两电极管的虹吸管部位不能有气泡；（3）标准电池不能大角度倾斜，更不能反转倒置。该实验中的缺点：（1）电池难以实现恒温；

（2）铜电极的电极电势复现性差。实验六：溶液表面张力的测定—最大泡压法 操作要点：

（1）测定用的毛细管一定要洗干净，否则气泡可能不呈单泡逸出，而使压力读书不稳定，如发生此种现象，毛细管应重洗；

（2）毛细管一定要与液面保持垂直，管口刚好与液面相切；（3）温度保持恒定，否则对γ的测定影响较大 实验改进：

用最大泡压法测定表面张力时，要求待测液面正好与毛细管底端相切，也是该实验最困难的地方，如果预先可做标记（有刻度的大试管更好）表示液面的高度，则可根据标记倒入溶液，不会偏移太多，可减小观察的误差。实验七：乙酸乙酯的皂化 操作要点：

（1）实验所用蒸馏水必须是新煮过的而不是放置已久的；

（2）称量乙酸乙酯时动作要迅速，防止液体挥发以保证实验的精确度；（3）用洗耳球把乙酸乙酯溶液压入氢氧化钠溶液时动作要迅速。同时不能用力过大，以防止损坏双管电导池；

（4）初次对电导仪进行调试时，应当先把范围选择器调至最大量程位置。每次用电导仪进行测量时，都应当提前进行仪器校正。实验讨论：

1、影响实验准确度，作图时线性不佳的主要因素：（1）恒温槽的温度超过正负0.5℃范围；（2）配制的蒸馏水放置太久；（3）使用电导率仪进行测量时，若不经常进行仪器校正，会产生测量误差。

2.活化能的影响因素：由于测量的温度只有两个点（25℃和35℃）也许这两点都是偏离直线的，所以实验应多测量多个点才使得结果更加准确。实验八：丙酮碘化 操作要点：

（1）反应要在恒温下进行，各反应物在混合前必须恒温；（2）混合反应溶液时操作必须准确迅速；（3）应使用同一比色皿，同一位置。实验讨论：

在一定条件下，特别是卤素浓度较高时，碘化反应并不停留在一元卤化酮，会形成多元取代，所以应测量初始一段时间的反应速率。但当碘的浓度偏大或丙酮及酸的浓度偏小时，因不符合朗伯比尔定律，读数误差较大。实验九：蔗糖的转化

实验讨论：蔗糖的水解在酸性介质中进行时，H+为催化剂，故反应是一复杂反应。反应的计量方程式显然不表示此反应的机理，反应不是双分子反应。本反应视为一级反应，完全是由实验得出的结论。实验建议：

（1）处理数据的方法：用㏑（аt--а∞）对时间作图，用二次曲线拟合，得到的结果在误差范围内可能会更加精确；

（2）由于温度对数据结果影响较大，最好可在旋光仪上配置恒温装置。实验十：希托夫法测定离子的迁移数 操作要点：

（1）电镀液不可装太多，只要浸没阴极铜即可，否则防止铜镀到上面，导致实验结果产生误差；

（2）实验过程中凡能引起溶液扩散，搅动等因素必须避免，电极阴阳两极的位置能对调，迁移数管及电极不能有气泡，两极上的电流密度不能太大；（3）使用电泳仪的直流电源设备要注意接上或断开外电源时，仪器的开关应处在关的位置；

（4）中间区溶液的浓度若发生明显变化实验应该重做。实验心得：

通过这个学期的大学物化实验，我体会颇深，首先，我通过做实验了解了许多实验的基本原理和实验方法，学会了基本物化量的测量分析方法，基本仪器的使用方法等；其次，学会了团队协作，同时也提高了动手能力以及基本操作技能训练，并且我也深深感受到做实验要具备科学的态度，认真态度和创造性思维。在老师的耐心讲解以及细心指导下，实验技能有所提高，接触了新仪器的使用方法，学会了将课堂上的知识运用到实验中去。在实处理实验报告时，也要把误差的原因真正分析到点上，在实验数据处理时要懂得可疑值取舍，以及误差具有传递性；还有数据处理的方法：列表法，作图法，数字函数法，其中用到最多的也就是作图法了。作图中很多细节也是值得注意的，比如坐标值得选取，单位的表示，坐标轴的确定等。

这次物化实验对我的影响很大，在老师给我们的相关材料上，给我们讲了实验的重要性以及实验的严谨性，还有对实验数据的处理和误差分析，实验注意事项，以及物理化学实验数据的表示法（列表法、作图法和数学方程式法），还有对残差的处理方法（平均法和最小二乘法）。在实验中我们还懂得了各种实验仪器，量具以及器件，让我们以后在做实验有初步的了解。为我们以后在实验室做实验打下了扎实的基础，让我们深刻体会到了实验的重要性。

总之，通过物理化学实验还培养了严肃认真、一丝不苟的工作作风。培养了我细致观察实验现象、准确测定实验数据、正确记录和处理数据、得出正确的实验结果以及实事求是的科学态度和严肃认真、一丝不苟的工作作风。同时也非常感谢两位老师对我们的悉心指导。参考文献

【清华】物化实验报告sy 篇3

学号：2010011825

班级：化 01

同组实验者：肖雅博 实验日期：2013.3.6

提交报告日期：2013.3.11 带实验老师：刘晓慧引言 1.1 实验目的 1． 了解恒温槽的原理，初步掌握其装配和调试的基本技术。

2． 分析恒温槽的性能，找出合理的最佳布局。

3． 掌握水银接点温度计、热敏电阻温度计、继电器、自动平衡记录仪的基本测量原理和使用方法。

1.2 实验原理 许多物理化学实验都需要在恒温条件下进行。欲控制被研究体系的某一温度，通常采取两种方法：一是利用物质相变时温度的恒定性来实现，叫介质浴。如：液氮（-195.9℃）、冰－水（0℃）、沸点水（100℃）、干冰－丙酮（-78.5℃）、沸点萘（218℃）等等。相变点介质浴的最大优点是装置简单、温度恒定。缺点是对温度的选择有一定限制，无法任意调节。另一种是利用电子调节系统，对加热或制冷器的工作状态进行自动调节，使被控对象处于设定的温度之下。

本实验讨论的恒温水浴就是一种常用的控温装置，它通过继电器、温度调节器（水银接点温度计）和加热器配合工作而达到恒温的目的。其简单恒温原理线路如图 2-1-1所示。当水槽温度低于设定值时，线路 I 是通路，因此加热器工作，使水槽温度上升；当水槽温度升高到设定值时，温度调节器接通，此时线路 II 为通路，因电磁作用将弹簧片 D 吸下，线路 I 断开，加热器停止加热；当水槽温度低于设定值时，温度调节器断开，线路 II 断路，此时电磁铁失去磁性，弹簧片回到原来的位置，使线路 I 又成为通路。如此反复进行，从而使恒温槽维持在所需恒定的温度。

恒温槽由浴槽、温度计、接点温度计、继电器、加热器、搅拌器等部件组成。如图 2-1-2所示。为了对恒温槽的性能进行测试，图中还包括一套热敏电阻测温装置。现将恒温槽主要部件简述如下。

1.浴槽

浴槽包括容器和液体介质。根据实验要求选择容器大小，一般选择 10L 或者20L 的圆形玻璃缸做为容器。若设定温度与室温差距较大时，则应对整个缸体保温。以减少热量传递，提高恒温精度。

恒温槽液体介质根据控温范围选择，如：乙醇或乙醇水溶液（-60－30℃）、水（0－100℃）、甘油或甘油水溶液（80－160℃）、石蜡油、硅油（70－200℃）。本实验采用去离子水为工作介质，如恒温在 50℃以上时，可在水面上加一层液体石蜡，避免水分蒸发。

2.温度计

观察恒温浴槽的温度可选择 1/10℃水银温度计，测量恒温槽灵敏度则采用热敏电阻测温装置。将热敏电阻与 1/10℃温度计绑在一起，安装位置应尽量靠近被测系统。

3.接点温度计（温度调节器）

接点温度计又称接触温度计或水银导电表，如图 2-1-3 所示。它的下半段是水银温度计，上半段是控制指示装置。温度计上部的毛细管内有一根金属丝和上半段的螺母相连，螺母套在一根长螺杆上。顶部是磁性调节冒，当转动磁性调节冒时螺杆转动，可带动螺母和金属丝上下移动，螺母在温度调节指示标尺的位置就是要控制温度的大致温度值。顶部引出的两根导线，分别接在水银温度计和上部金属丝上，这两根导线再与继电器相连。当浴槽温度升高时，水银膨胀上升，与上面的金属丝接触，继电器内线圈通电产生磁场，加热线路弹簧片吸下，加热器停止加热。随着浴槽热量的散失，温度下降，水银收缩并与上面的金属丝脱离，继电器电磁效应消失，弹簧片回到原来位置，接通加热电路，系统温度回升。如此反复，从而使系统温度得到控制。

需要注意的是，温度调节指示标尺的刻度一般不是很准确，恒温槽温度的设定和测量需要 1/10℃温度计来完成。

接点温度计是恒温槽的重要部件，它的灵敏度对控温精度起着关键作用。

4.继电器

继电器与加热器和接点温度计和加热器相连，组成温度控制系统。实验室常用的继电器有晶体管继

电器和电子管继电器。典型的晶体管继电器电路如图 2-1-4 所示，它是利用晶体管工作在截止区以及饱和区呈现的开关特性制成的。其工作过程是：当接点温度计 T r 断开时时，E c 通过 R k 给锗三极管 BG 的基极注入正向电流 I b，使 BG 饱和导通，继电器 J 的触点 K 闭合，接通加热电源。当温度升高至设定温度，接点温度计 T r 接通，BG 的基极和发射极被短路，使 BG 截至，触点 K 断开，加热停止。当继电器 J 线圈中的电流突然变小时，会感生出一个较高的反电动势，二极管 D 的作用是将它短路，避免晶体管被击穿。必须注意的是，晶体管继电器不能在高温下工作，因此不能用于烘箱等高温场合。

5.加热器

常用的是电加热器。加热器的选择原则是热容量小、导热性能好、功率适当。加热器功率的大小是根据恒温槽的大小和所需控制温度的高低来选择的。通常我们都在加热器前加一个和加热器功率相适应的调压器，这样加热功率可根据需要自由调节。

6.搅拌器

搅拌器的选择与工作介质的粘度有关，如：水、乙醇类粘度较小的工作介质选择功率 40W 左右的搅拌器。若工作介质粘度或搅拌棒的叶片较大时，应选择功率大一些的搅拌器。

7.热敏电阻测温装置

用来对恒温槽的性能进行测试，测温原理见附录温度的测量与控制。

综上所述，恒温效果是通过一系列元件的动作来获得的。因此不可避免地存在着滞后现象，如温度传递、感温元件、继电器、加热器等的滞后。因此，装配时除对上述各元件的灵敏度有一定要求外，还应根据各元件在恒温槽中作用，选择合理的摆放位置，合理的布局才能达到理想的恒温效果。灵敏度是恒温槽恒温好坏的一个重要标志。一般在指定温度下，以 T 始、T 停 分别表示开始加热和停止加热时槽内水的温度（相对值），以1/2()T T T  始 停为纵坐标，时间 t 为横坐标，记录仪自动画出灵敏度曲线如图 2-1-5。

若最高温度为 T 高，最低温度为 T 低，测得恒温槽的灵敏度为 2ET TT 低 高 通过对上述曲线分析可以看出图中（a）表示灵敏度较高；（b）表示灵敏度较低；（c）表示加热功率偏大。如果加热器功率偏小，则达不到设定的温度值。

实验操作 2.1 实验药品、仪器型号及测试装置示意图

2.1.1 实验药品及仪器

恒温槽 1 套：玻璃缸、电动搅拌器、1/10℃温度计、电加热器、水银接点温度计、继电器、调压器；热敏电阻温度计、电阻箱、甲电池、电桥盒、记录仪、放大镜等各一个。

2.1.2 测试装置示意图 2-1-2

2.2 实验条件

实验温度：21.0℃

大气压：101.38kPa

湿度：28.0%

2.3 实验操作步骤及方法要点 2.3.1

实验操作步骤 1.恒温槽的装配

根据所给原件和仪器，按图 2-1-2 安装恒温槽，接好线路，经教师检查后方可接通电源。

2.恒温槽的调试

玻璃缸中加入去离子水，约总容积的 4/5。打开搅拌器（中速搅拌）、继电器，旋开接点温度计上端磁性调节帽固定螺丝，调节设定温度至比要实际设定的温度低一些的位置（因为温度调节指示标尺的刻度一般不是很准确，适当调低一点防止超过需要设定的温度）。为了保证恒温效果，单加热型恒温槽温度设定最低值一般要高于室温 8～10℃，加热开始。开始可将加热电压调到 200V 左右，待接近设定温度时，适当降低加热电压。仔细观察 1/10℃温度计，当水槽温度将要达到设定值时，旋转磁性调节帽，使接点温度计上部的金属丝与水银处于通断的临界状态，可通过继电器指示灯判断。再观察 1/10℃温度计，所示温度是否是要设定的温度，进行进一步调整。最后拧紧磁性调节帽的固定螺钉。

3.温度波动曲线的测定

打开记录仪和电桥盒上的开关，用电阻箱将电桥调平衡，使记录笔停在记录纸的中部。判断电桥电源极性是否连接正确，增大阻值，记录笔应向右侧移动，升高温度，记录笔也应向右侧移动。反之则需将甲电池正负接线对调。记录仪走纸速度定在定在 4mm/min，开始记录，记录 7～8 个周期即可停止。

4.布局对恒温槽灵敏度的影响

改变各元件间的相互位置，重复测定温度波动曲线，找出一个合理的最佳布局。

5.影响温度波动曲线的因素

选定某个布局，分别改变加热电压（加热功率）和搅拌速

度，测定温度波动曲线与未改变条件的温度波动曲线比较。

6.测定热敏电阻温度计的仪器常数（℃/格）

将恒温槽温度升高，用放大镜观察 1/10℃温度计，记录温度升高 0.3～0.5℃记录笔移动的格数。

7.实验结束。剪下记录纸，将仪器复原。

2.3.2

注意事项 1.1/10℃温度计所在位置就将来利用这个恒温槽做实验的系统所在区域。

2.温度设定时要留有提前量，避免水槽温度高于欲设定值。

3.接点温度计的刻度不是很准确，温度的设定与测量以 1/10℃温度计为准。

结果与讨论 3.1 原始实验数据 及计算结果 设定温度：30.0℃ 另附实验记录纸 1.测定热敏电阻温度计的仪器常数：

仪器常数=△T/走纸格数 表 表 1 水温降低 0.2℃ 记录笔走纸格数 组号 号 水温 降低△ △T/ ℃ 走纸格数 仪器常数/ ℃ 1 0.2 33.5 0.00597

2.确定最佳布局：

搅拌档数：4

电压：100V 搅拌器：；

加热器：；

接点温度计：；

热敏电阻和温度计：

灵敏度计算：

生物化学英语词汇 篇4

活性中心

a specialized region of an enzyme where the enzyme interacts with the substrate and catalyzes its conversion to products. many aminoacyl residues contribute to the active center.

adenylyl cyclase.

腺苷酸环化酶

an enzyme that catalyzes the synthetic reaction of cyclic amp from atp in response to hormones such as epinephrine and glucagon.

alanine-glucose cycle.

丙氨酸-葡萄糖循环

a cooperative pathway between liver and muscle in which the ammonia and carbon from amino acid metabolism are removed from the muscle as alanine, taken up by the liver, transaminated to pyruvate, converted into glucose, and shipped out back to the muscle.

albumin.

清蛋白

albumin makes up 50% to 55% of the proteins of plasma and is thought to be the main contributor to osmotic pressure of blood. another important function is that albumin has very broad and non-specific binding properties.

allosteric enzyme.

变构酶

allosteric enzymes are enzymes whose activity at the catalytic site may be modulated by the presence of allosteric effectors at an allosteric site. allosteric means “occupy another space”, so an allosteric effector occupy another space, giving an effect on enzymes.

allosteric regulation.

变构调节

a type of enzyme regulation in which an effector binds to one site on the enzyme and increase or decreases the activity at another site. allosteric regulation provides a rapid means for regulation of their activity.

aminoacyl-trna synthetase.

氨基酰trna合成酶

the enzymes are responsible for the recognition and attachment of the 20 amino acids to specific trna.

anticodon.

反密码子

the template-recognition site on trna is a sequence of three bases called the anticodon, which recognizes a complementary sequence of three bases on mrna.

apoprotein.

载脂蛋白

the protein moiety of a lipoprotein. they mediate the interaction between lipoproteins and tissues.

apoptosis.

细胞凋亡

programmed cell death. the programmed cell death is tightly regulated, which plays important roles in physiologic processes. typical morphologic changes can be observed in apoptosis. one or more endonucleases degrade dna, leading to characteristic ladder of discrete dna fragment on electrophoresis.

bile salts.

胆汁酸盐

salt form of bile acids and their conjugates. since bile contains significant quantities of sodium and potassium and the ph is alkaline, it is assumed that the bile acids and their conjugates are in a salt form, so called “bile salts.”

biotin.

生物素

a cofactor involved in carboxylation reactions. most enzymes that catalyze the atp-dependent addition of co2 to a substrate (like acetyl-coa carboxylase) requires the cofactor biotin.

calcitonin.

降钙素

a 32-amino-acid peptide secreted by the parathyroid. the dominant biological action of calcitonin is to mediate a lowering of serum calcium levels. the hypocalcemic and hypophosphatemic effects of calcitonin are believed to be due to an inhibition of pth-mediated calcium resorption.

calcium-binding protein.

钙结合蛋白

1,25(oh)2-d3 stimulates gene transcription and formation of specific mrna that codes for “calcium-binding protein”, also called “calbindin”. three distinct vitamin d-induced “calbindin” have been isolated. two of them are found exclusively inside the intestinal and kidney cells, which are actively involved in calcium translocation.

calmodulin.

钙调蛋白

a ubiquitous calcium sensor in eukaryotes, regulates the activities of many intracellular proteins. the binding of ca2+ to multiple sites in calmodulin induces a major conformational change that converts it from an inactive to an active form. activated calmodulin binds to many enzymes and modifies their activities.

camp.

环化腺苷一磷酸

second messenger for increased demand for energy and glucose. camp activates camp-dependent protein kinase. increased camp levels are associated with increased protein phosphorylation. increases in the camp concentration cause activation of glycogen degradation, increased fatty acid breakdown, stimulation of glycolysis in muscle, and stimulation of gluconeogenesis in the liver.

camp-dependent protein kinase，pka.

依赖camp的蛋白激酶

most effects of cyclic amp in eukaryotic cells are mediated by the activation of a single protein kinase. this key enzyme is called protein kinase a or camp-dependent protein kinase, which alters the activities of target proteins by phosphorylating specific serine or threonine residues.

capping.

帽子生成

putting a 7-methylguanosine triphosphate on the 5’ end of an mrna molecule. capping is involved in the recognition of mrna and may increase the stability of the rna by preventing the attack of 5’exonucleases.

carnitine shuttle.

肉碱穿梭

gets fatty acyl groups into mitochondria. fatty acyl-coa in the cytosol is transferred to carnitine to make fatty acyl carnitine, which is transported into mitochondria. once inside, the fatty acyl group is transferred to coa and the carnitine is returned to the mitochondrial membrane.

catabolic pathway.

分解代谢途径

degradative metabolism. catabolic pathways involve oxidative processes that release free energy.

catabolic repression.

分解代谢阻遏

catabolic repression means that an intermediate in a sequence of catabolic enzyme-catalyzed reactions has ability to repress synthesis of catabolic enzymes.

catabolite gene activator protein, cap.

分解(代谢)物基因激活蛋白

a camp-binding protein that is capable of stimulating transcription by binding to certain promoter sites. it consists of two subunits, each of which contains a dna-binding domain and a camp binding domain.

cdna library.

cdna文库

a library is a collection of recombinant clones. cdna library represents the population of mrna in a tissue. see also cdna.

cdna.

互补dna

complementary dna. cdna copies from a population of cytoplasmic mrna using enzyme reverse transcriptase, converting the cdna single strands to double-stranded dna. the reverse transcriptase copies rna templates into dna-rna hybrids. after the rna in these hybrids is specifically destroyed, double-stranded dna may be produced by dna polymerase. cdna is a copy of an mrna so that it contains only the exon sequences.

cis-acting element.

顺式作用元件

this word described the regulatory interactions between two dna sequences on the same gene. an enhancer or repressor sequence in the dna is a cis-acting element or factor that affects the transcription of the gene.

cistron.

顺反子

a stretch of dna that carries the information for a polypeptide chain is called cistron.

clone.

克隆

group of cells or sequences of dna that are identical with a single parental cell or molecule.

coding strand.

编码链

the coding strand of dna has the same sequence as that of the rna transcript except for t in place of u. it is so-called because it matches the rna transcript that encodes the protein. the coding strand is also known as the sense strand.

codon.

密码子

each amino acid in a protein is specified by an mrna sequence of three nucleotides, which is called a codon.

coenzyme.

辅酶

a molecule bound to an enzyme and is essential for its activity. the coenzymes allow the enzyme to have functional groups that are not available from the side chains of the amino acids.

competitive inhibition.

竞争性抑制

substrate and inhibitor combine at the same site and result in raising the apparent km for the substrate.. in competitive inhibition, inhibitor can be completely displaced by a high concentration of the substrate.

configuration.

构型

the stereochemical arrangement of atoms in a molecule. configuration cannot be changed without breaking and reforming covalent bonds.

conformation.

构象

differences in rotation around bonds. the conformation of a molecular can be changed by simply rotating groups around single bonds.

conjugated bilirubin.

结合胆红素

adding glucuronic acid molecules to bilirubin. hepatocytes perform the process and convert bilirubin to a water-soluble form.

cosmid vector.

柯斯质粒载体

a special class of artificially constructed e.coli plasmids that carry the λ cos site, which allows them to be packaged intoλphage particles for efficient introduction into bacteria.

creatine kinase.

肌酸激酶

kinases incorporate phosphate from atp into the substrate. creatine kinase converts creatine to creatine phosphate, a major energy reserves in muscle.

de novo synthesis.

从头合成

biosynthesis of nucleotides with simple materials. purine and pyrimidine ribonucleotides are synthesized via two pathways, in which the purines are built as nucleotides via phosphoribosyl intermediates, whereas the pyrimidine ring is completed to the stage of orotate before coupling to ribose.

degenerate.

简并

more than one codon can specify the same amino acid and all codons are unambiguous in that each specifies no more than one amino acid.

denaturation.

变性

destroy the secondary, tertiary, and quaternary structure of a protein, dna, or rna molecule.

dna damage.

dna损伤

dna damage is that changes in the dna sequence resulted from copying errors and the effects of various physical and chemical agents or carcinogens，which alters one or more nucleotides in dna.

dna polymerase.

dna聚合酶

the principal synthetic enzyme, dna polymerase, extends the primers in the 5’ to 3’ direction by catalyzing addition of deoxyribonucleoside 5’-phosphates to the primer 3’ends. synthesis proceeds in the 5’ to 3’ direction as the template strand is read in the 3’ to 5’ direction.

dna replication.

dna复制

generation of a new copy of double-stranded dna from a parental dna molecule.

domain.

结构域

some polypeptide chains fold into two or more compact supersecondary structures. these compact globular supersecondary structures are called domains, which is one level of protein’s structures between secondary structure and tertiary structure.

effector.

效应剂

a class of small molecules capable of binding at a regulatory site. the binding of an effector changes the conformation of the enzyme so as to alter the kinetic properties of the catalytic site.

enhancer.

增强子

the sequence elements that can increase the rate of transcription initiation of eukaryotic genes. enhancers have no promoter activity of their own but they can exert their stimulatory actions over distances of several thousand base pairs.

enterohepatic circulation.

肠肝循环

the primary bile acids are synthesized in the liver and the secondary bile acids are formed in the intestine. the secondary bile acids are absorbed in the intestine, returning to the liver then recycle between intestine and liver, which is known as the entero-hepatic circulation.

epidermal growth factor (egf) .

表皮生长因子

epidermal growth factor can stimulates growth of many epidermal and epithelial cells. also see “growth factor”.

essential amino acid.

必需氨基酸

the amino acids that humans can not synthesize. the human diet must contain these amino acids to support growth or maintain health.

exon.

外显子

regions that are retained in the mature rna.

fad.

黄素腺嘌呤二核苷酸

flavin adenine dinucleotide. fad is derived from vitamin riboflavin, which serves as cofactor for oxidation and reduction reactions.

fat.

脂肪

mainly stored as triglyceride in adipose tissue. the adipose tissue releases fatty acids by the activation a hormone-sensitive lipase that catalyzes the hydrolysis of the triglyceride. the fatty acids are then transported through the serum and oxidized via b oxidation in the tissues to yield energy.

feedback inhibition .

反馈抑制

feedback inhibition refers to the inhibition of the activity of an enzyme in a biosynthetic pathway by an end product of that pathway.

ferritin.

铁蛋白

intracellular form of iron storage. it stores iron that can be used as condition requires.

fh4.

四氢叶酸

tetrahydrofolate. a reduced form of folic acid involved intimately in one-carbon transfer reactions.

gene.

基因

a stretch of dna that carries the information for a polypeptide chain is called gene or cistron. also see cistron.

genome.

基因组

total information of gene contained in a cell, an organism or a virus.

genomic dna library.

基因组dna文库

fragments of dna from the genome of some organism. they are prepared from the total dna of a cell line or tissue by performing partial digestion of total dna with a restriction enzyme that cuts dna frequently. it contains exons, introns, untranslated regions that can occur in dna.

glucogenic amino acid.

生糖氨基酸

the amino acid that yield pyruvate or citric cycle intermediates.

gluconeogenesis.

糖异生

making glucose or glycogen from noncarbohydrate. the term used to include all mechanisms and pathways responsible for converting noncarbohydrate to glucose or glycogen.

glycerol-a-phosphate shuttle.

a-磷酸甘油穿梭

get electron from cytoplasmic nadh into the mitochondria so that 2 atps can be made by oxidation of the nadh. the enzymes of the shuttle in mitochondria is linked to the respiratory chain via a flavoprotein.

glycolysis.

酵解

metabolic pathway that provides pyruvate as fuel to the citric cycle or for fat synthesis. in the absence of oxygen, lactate is produced from the pyruvate to regenerate nad+ so that the pathway can continue to work in the absence of oxygen.

gout.

痛风

it is an inherited metabolic disease that affects the joints and kidneys caused by hyperuricemia. though some patients have a partial deficiency of hypoxanthine-guanine phosphoribosyl transferase (hgprt), it is not sole cause of the disease.

growth factor.

生长因子

small polypeptides (more properly called cytokines) that stimulate the growth of particular classes of cells. the factors have a variety of effects, including changes in the uptake of small molecules, initiation or stimulation of the cell cycle, and ultimately cell division. examples of secreted cytokines are egf (epidermal growth factor), pdgf (platelet-derived growth factor), and insulin.

guide rna.

指导rna

guide rna is a sequence that is complementary to the correctly edited mrna.

hairpin structure.

发夹结构

a double-helical stretch formed by base paring between neighboring complementary sequences of a single strand of dna or rna.

helicase.

解链酶

an enzyme whose activity involved in dna replication that relieves the strain associated with unwinding the dna double helix during replication.

heme.

血红素

a cofactor consisting of a porphyrin ring containing an iron atom. heme has different functions depending on the protein that used them as a cofactor. heme are used to carry oxygen without oxidizing it in hemoglobin and myoglobin, but in other proteins, like cytochrome p450, the heme iron produces a very reactive iron-oxygen species at the active site.

hemoglobin.

血红蛋白

hemoglobin is the oxygen-carrying system found in erythrocytes, which transports oxygen from the lungs to all tissues of the body. the quaternary structure of hemoglobin confers its allosteric properties that adapt it to its biologic roles and permit its precise regulation.

hexokinase.

己糖激酶

responsible for the phosphorylation of glucose for entry into glycolysis, glycogen synthesis, or the pentose phosphate pathway.

hnrna.

不均一核内rna

heterogeneous nuclear rna. they are formed in the nucleus that is a precursor to mrna, which has both the intron and exon sequences.

hormone response element, hre.

激素反应元件

a specific dna sequences capable of binding activated receptors. these elements regulate the gene expression. both steroids and peptide hormones exert their effects on transcription through hres, but the initial reactions are different.

housekeeping gene.

管家基因

the genes that are expressed at a reasonably constant rate and not known to be subject to regulation.

induction.

诱导

synthesis of a particular protein in response to a signal stimulation in cellular metabolism. for example, the synthesis of an enzyme can be induced by its substrate.

intron.

内含子

the mosaic nature of eukaryotic genes is discontinuous. the primary transcript of a gene contains the regions that are not present in the mrna. regions that are removed from the primary transcript are called introns.

isoelectric point.

等电点

the ph at which a molecule has a net zero charge.

isomerase.

异构酶

an enzyme that catalyzes an intramolecular rearrangement.

isozyme.

同工酶

distinct physical forms of an enzyme with the same catalytic activity. separation and identification of isozymes is of diagnostic value.

jaundice.

黄疸

when bilirubin in the blood reaches a certain concentration, hyperbilirubinemia exists and bilirubin diffuses into the tissues, which then became yellow. the condition is called jaundice.

ketogenic amino acid.

生酮氨基酸

an amino acid that yields only acetyl-coa. they can not yield pyruvate or tricarboxylic acid cycle intermediates.

ketone bodies.

酮体

acetoacetate, hydroxybutyrate and acetone. at high rate of fatty acid oxidation, the liver produces considerable quantities of acetoacetate and hydroxybutyrate. the former continually undergoes spontaneous decarboxylation to yield acetone. ketone bodies are metabolized in muscle and brain as an energy source.

km.

米氏常数

if an enzyme follows hyperbolic kinetics, the km is equal to the substrate concentration at which the reaction rate is half its maximal value.

ligase.

连接酶

a ligase catalyzes the joining of two pieces of dna covalently. dna ligase joins the backbone phosphates in a phosphodiester bond.

lipids.

脂类

lipids consist of a diverse set of hydrophobic molecules including triglycerides, phospholipids, steroids, and so forth. it is soluble in organic solvents like chloroform or ether.

malate-aspartate shuttle.

苹果酸-天冬氨酸穿梭

gets electrons from cytoplasmic nadh into the mitochondria so that 3 atps can be produced by oxidation of the nadh.

mitogen-activited-protein kinase ( mapk).

有丝分裂原激活蛋白激酶

mitogen-activated protein kinase (mapk) is one of the most ancient signaling molecules and is involved in multiple cellular processes, including cell proliferation, cell growth, and cell death.

messenger rna (mrna).

信使rna

the rna in cytoplasm that serve as templates for protein synthesis. the primary rna transcript is processed to mrna by adding a cap and a tail and removing introns.

nad+-nadh.

辅酶i

nicotinamide adenine dinucleotide. nadh is an electron carrier. nad+ accepts two electrons and a proton from substrates and ultimately transfers them to the electron transport chain to make three atps and h2o.

nicotinic acid.

尼克酸

a vitamin that serves as a source of the pyridine ring of nad+ and nadp+. dietary deficiency of nicotinic acid can lead to pellagra. humans can synthesize nicotinic acid that derived from tryptophan.

non-competitive inhibition.

非竞争性抑制

in non-competitive inhibition, inhibitor bind to a different domain of an enzyme, lowering the maximum velocity but with normal km.

nucleosides.

核苷

a nucleoside consists of a purine or pyrimidine base linked to a pentose.

nucleotides.

核苷酸

a nucleotide is a phosphate ester of a nucleoside on 3’- or 5’-carbon of ribose. phosphorylation on 5’-carbon of ribose is the one most commonly esterified forms.

okazaki fragment.

冈崎片段

the short discontinuous segments, which later are joined by dna ligase, are called okazaki fragment after their discoverer.

oncogene.

癌基因

oncogenes are the genes capable of changing a normal cell into a transformed cells. many oncogenes encode abnormal signal transduction proteins involved in imitating the action of polypeptide growth factor.

operator.

操纵序列

the operator is a dna segment adjacent to the structural genes. the binding of the repressor to the operator prevents the transcription of these genes.

operon.

操纵子

a collection of prokaryotic structural genes that are present in a linear array and whose expression is controlled by the same regulatory region of the dna. this arrangement allows simple control over the expression of proteins that are all needed for a common job. it should be noted that an operon includes both operator and its associated structural genes.

osteomalacia.

软骨病

osteomalacia is caused by vitamin d deficiency in the adult, which leads to softening and weakening of bones.

oxidation.

氧化

when something is oxidized, something else must become reduced. with removal of an electron, ferrous is oxidized to ferric ion. so oxidation is a process with the loss of electrons.

oxidative phosphorylation.

氧化磷酸化

the process in which atp is formed as a result of the transfer of electrons from nadh or fadh2 to oxygen by a series of electron carriers.

parathyroid hormone (pth) .

甲状旁腺素

parathyroid hormone, an 84-amino acid-containing protein, is secreted by the chief cells of the parathyroid gland. the biological actions of pth are related to regulate calcium metabolism.

pentose phosphate pathway.

磷酸戊糖途径

an alternative route for the metabolism of glucose. the pathway generates both nadph for reductive syntheses and ribose residues for nucleotide biosynthesis.

peptide bond.

肽键

the bond that the a-carboxyl group of one amino acid is joined to the a-amino group of another amino acid by an amide bond in a polypeptide.

phospholipase c.

磷脂酶c

the activation of the phospholipase c is mediated by g protein. the active form of the enzyme catalyzes the hydrolysis of a membrane-bounded substrate to form two second messengers, diacylglyceride and inositol 1,4,5-triphosphate. diacylglyceride is capable of activating protein kinase c. inositol 1,4,5-triphosphate is effective for the release of calcium from intracellular calcium pool.

plasmid.

质粒

independently replicating circular pieces of dna whose natural function is to confer antibiotic resistance to the host cell.

platelet-derived growth factor.

血小板源生长因子

platelet-derived growth factor can stimulates growth of messenchymal and glial cells. also see “growth factor”.

point mutation.

点突变

it is cause by a single base change of dna gemone, which in turn results in a change in the messenger rna, a structural abnormality of gene expression.

polycistronic mrna.

多顺反子mrna

a single mrna that encodes more than one separately translated protein is referred to as a polycistronic mrna, which contains multiple independent translation start and stop codons for each cistron.

polypeptide chain.

多肽链

many amino acids joined by peptide bonds form a polypeptide chain, which has two different ends, i.e. n-terminal and c-terminal respectively.

polyribosome.

多核糖体

an mrna molecule with many ribosomes bound to it. many ribosomes can translate the same mrna simultaneously.

primary transcript.

初级转录本

primary transcript is the original unmodified rna product corresponding to a transcription unit.

primase.

引物酶

primase catalyzes polymerization of ribonucleoside 5’-triphosphates to form rna primers. the sequence of monomer addition is dictated by a template strand of dna and the chain lengths of primers are usually 10-50 nucleotides.

promoter.

启动子

promoter is a region of dna involved in binding of rna polymerase to initiate transcription.

prosthetic group.

辅基

many proteins require tightly bound, specific nonpolypeptide units for their biological activities. such a unit is called a prosthetic group.

protease.

蛋白酶

an enzyme that hydrolyzes the amide bonds in a protein. most proteases recognize a specific type of amino acid side chain and cleave the protein at specific points.

proto-oncogene.

原癌基因

normal cellular genes with the potential to become oncogenes are called proto-oncogenes or cellular oncogenes. these genes were conserved in a wide range of eukaryotic cells. the conserved sequences were important components of normal cells and their products are believed to play important roles in normal differentiation and other cellular process.

pyridoxal phosphate.

磷酸吡多醛

all transamination reactions require the coenzyme pyridoxal phosphate. the important functional groups of the coenzyme are the aldehyde group, which can form a schiff base with the a-amino group of an amino acid and facilitate transamination.

rate-limiting enzyme.

限速酶

enzymes catalyzing committed steps in unidirectional anabolic and catabolic pathways, which act as natural governors of metabolic flow and represent the most efficient regulatory intervention.

receptor.

受体

all of receptors are proteins that can selectively bind specific molecule and initiate their biologic effects.

recombinant dna.

重组dna

information exchanging by breaking and joining chromosomal dna. recombination can occur between genes with similar sequences or between genes with different sequences.

reduction.

还原

chemically, reduction is defined as the gain of electrons. nad+ is reduced to nadh. it follows that reduction is accompanied by oxidation of an electron donor.

replication.

复制

generation of a new copy of double-stranded dna from a parental dna molecule.

residue.

残基

in a polypeptide chain, an amino acid unit is called a residue.

respiratory chain.

呼吸链

exists in the mitochondria, consists of a number of redox carriers. the respiratory chain provides most of the energy captured in metabolism.

restriction endonuclease.

限制性内切核酸酶

the classes of endonucleases cut dna at specific dna sequences within the molecule.

reverse transcriptase.

反转录酶

an rna-directed dna polymerase in retroviruses; capable of making dna complementary to an rna.

reverse transcription.

反转录

rna-directed synthesis of dna, catalyzed by reverse transcriptase.

ribosomes.

核糖体

complex cytoplasmic particles each consisting of two ribonucleoprotein subunits. translation of mrna occurs on it.

ribozyme.

核酶

a class of rnas that meet all the classic criteria for definition as enzymes. these catalytic rnas catalyze highly specific hydrolysis of phosphodiester bonds in rnas and are important in the processing events involved in maturation of pre-mrna.

rickets.

佝偻病

vitamin d deficiency in childhood produces rickets characterized by low plasma calcium and phosphorus levels and by poorly mineralized bone with associated skeletal deformities.

rna editing.

rna 编辑

the information content of some mrna is altered following transcription by process other than rna splicing.

rna polymerase.

rna聚合酶

rna polymerase is an enzyme that synthesizes rna using a dna template.

rrna.

核蛋白体rrna

ribosomal rna. structural components of ribosomes. there are several discrete size classes of rrna, usually referred to by their sedimentation coefficients as 5s, 5.8s, 18s, and28s in eucaryotic cells.

s-adenosyl methionine, sam.

s腺苷蛋氨酸

sam is a major donor of one-carbon unit at the methyl oxidation state, which is formed from methyl-thf and homocysteine by a vitamin b12-dependent reaction.

salting out.

盐析

the solubility of the proteins is lowered at high salt concentrations, so-called the “salting out”. it can be used to fractionate proteins because the dependence of solubility on salt concentration differs from one protein to another.

salvage pathway.

补救合成途径

the pathways that purines and pyrimidines derived from nucleic acid catabolism react with prpp and form the corresponding ribonucleotides. corresponding deoxyribonucleotides are produced by reduction of the ribonucleoside diphosphates, using nadph as the reducing agent.

semiconservative replication.

半保留复制

dna replication follows a law called semiconservative replication, i.e., one of the strands of each daughter dna molecule is newly synthesized, whereas the other is passed on unchanged from the parent dna molecule.

sigma factor.

σ因子

sigma factor is the subunit of bacterial rna polymerase needed for initiation. it is the major influence on selection of binding sites (promoters).

signal transduction.

信号转导

the process by which an extracellular signal is amplified and converted to a cellular response. for example, growth factors act on the cell cycle and mitosis via transmembrane signal transduction.

snrna.

小核rna

small nuclear rna. they have roles in rna processing but are not directly involved in protein synthesis.

splicing.

剪接

splicing describes the removal of introns and joining of exons in rna; thus introns are spliced out, while exons are spliced together.

substrate.

底物

reagent in a catalytic reaction by an enzyme.

synthase.

合酶

a synthase is an enzyme that makes something but doesn’t directly require the hydrolysis of atp to do it.

synthetase.

合成酶

a synthetase requires the hydrolysis of atp to make the reaction go.

telomere.

端粒

specialized structure at the ends of chromosomes that allows replication of the extreme 5’ ends of the dna without loss of genetic information.

template strand.

模板链

the template strand, also known as the antisense strand, is one strand that the genetic information resides in the sequence of nucleotides in the double-stranded dna molecules. this is the strand of dna that is copied during nucleic acid synthesis.

terminator.

终止子

terminator is a sequence of dna , represented at the end of the transcript, that causes rna polymerase to terminate transcription.

thiamine pyrophosphate, tpp.

焦磷酸硫胺素

it is derived from the vitamin thiamine, which is required for decarboxylation of a-keto acids and also involved in some transfer reactions of aldehyde derivatives.

topoisomerase.

拓扑异构酶

enzymes that catalyze topologic changes of dna are called topoisomerases, which can relax or insert supercoils. topoisomer of dna can be interconverted only by cutting one or both dna strands and then rejoining them.

trans-acting factor.

反式作用因子

trans-acting factor is used to describe the effect of a product from one gene on the transcription of another gene.

transamination.

转氨基作用

the amino acid are degraded via reaction of transamination, in which the a-amino group is transferred to a acceptor a-ketoacid with production of the a-keto derivative of the amino acid.

transcription.

转录作用

the synthesis of rna using a dna template. rna polymerase catalyzes the synthesis and uses the antisense strand as a template.

transferrin.

运铁蛋白

transferrin carries two ferric ions and transfer them to cells having receptors for transferrin. association with transferrin diminishes the potential toxicity of free iron and directs iron to where it is required in the body.

translation.

翻译

the synthesis of protein directed by the nucleotides sequence of an mrna. translation occurs on ribosomes.

triglyceride.

甘油三酯

also called triacylglycerol. it is formed by glycerol molecule and three fatty acid chains, which attached through ester linkages.

trna.

转运rna

transfer rna. they serve as adaptor for the translation of the information in the sequence of nucleotides of the mrna into specific amino acids.

ubiquinone.

泛醌

a redox carrier presented in the respiratory chain, which is also called coenzyme q. it exists in mitochondria, linking the flavoproteins to cytochrome b.

uncouples.

解偶联

allow protons back into the mitochondria without making any atp.

upstream.

上游

upstream identifies sequence proceeding in the opposite direction from expression; for example, the bacterial promoter is upstream of the transcription unit, the initiation codon is upstream of coding region.

urea cycle.

尿素循环

the pathway that excess ammonia produced by deamination is excreted after conversion to urea is called urea cycle. since urea synthesis converts toxic ammonia to nontoxic urea, the defects in urea synthesis result in ammonia intoxication.

vectors.

载体

something that can be used to introduce recombinant dna into a host organism. an insert is the piece of dna that has been placed into the vector.

vitamin b12.

维生素b12

this vitamin is synthesized exclusively by microorganisms. in animals, it is conserved in the liver. the absorption of vitamin b12 in the intestine is mediated by receptor sites, i.e., intrinsic factor. in clinic, deficiency of vitamin b12 can lead to anemia.

vitamin d.

维生素d

cholesterol is the precursor of vitamin d. by various metabolic changes in the body, cholesterol is converted into calcitiol, which plays an essential role in the control of calcium and phosphorus metabolism.

zwitterion.

兼性离子

an amino acid exhibits dipolar ions (zwitterion) rather than un-ionized molecules at suitable ph. in the dipolar form of an amino acid, the amino group is protonated and the carboxyl group is dissociated so that a molecule has zero charge.

ρ factor.

ρ因子