课堂练习及课后作业

Home Work1Match the definition with the termsTerms: Cytoskeleton, minus end, protofilament, tubulin,Dynamic instability, neurofilament, intermediate filament, treadmilling, keratin, plus end1匹配的定义条款条款：骨架，负端，原丝，微管蛋白，动态不稳定，神经丝蛋白，中间丝，treadmilling ，角质蛋白，加上年底Definitions:1-1A linear chain of protein subunits joined end to end, which associates laterally with other such chains to form cytoskeleton components.直链蛋白亚基加入端到端，横向联营与其他此类链形成细胞骨架成分。

1-2The property of sudden conversion from growth to shrinkage, and vice versa, in a protein filament such as a microtubule or an actin filament.物业突然从增长转换收缩，反之亦然，如微管或肌动蛋白丝在蛋白丝。

1-3The end of a microtubule or an actin filament at which addition of monomers occurs most readily; the fast-growing end.微管或加入单体肌动蛋白丝最容易出现快速增长的最终结束。

1-4General term for the fibrous protein filaments (about 10 nm in diameter that form ropelike networks in animal cells.通用术语，纤维蛋白丝（直径约10纳米，在动物细胞中形成绳状的网络。

1-5The process by which a polymeric protein filament is maintained at constant length by addition of protein subunits at one end and loss of subunits at theother.通过该过程的聚合蛋白长丝在一端和在另一亚基的损失保持在恒定长度通过加入蛋白亚基的。

1-6System of protein filaments in the cytoplasm of a eukaryotic cell that gives the cell its shape and the capacity for directed movement.系统在真核细胞的细胞质中，它的形状和定向运动的能力给细胞蛋白丝。

2TRUE or FALSE1-7 The structural polarity of all microtubules is such that α-tubuliin is exposed at one end and β-tubulin is exposed at the opposite end.极性的所有微管的结构是这样的，α - tubuliin的一端露出，和β-微管蛋白在另一端露出。

1-8 The role of ATP hydrolysis in actin polymerization is similar to the role of GTP hydrolysis in tubulin polymerization: both serve to weaken the bounds in the polymer and thereby promote depolymerizaiotn.肌动蛋白聚合作用的ATP水解GTP水解微管蛋白聚合的作用类似：，都起到削弱的界限在聚合物中，从而促进depolymerizaiotn 。

1-9 Like actin filaments and microtubules, cytoplasmic intermediate filaments are found in all eukaryotes.如微丝和微管，细胞质中间丝在所有真核生物中发现。

1-10 Myosin II molecules have two motor domains and a rodlike tail that allows them to assemble into bipolar filaments, which are crucial for the efficient sliding of oppositely oriented actin filaments past each other.肌球蛋白II类分子有两个马达域和一个棒状的尾巴，使他们能够组装成双极细丝，这对于高效滑动的取向相反微丝过去对方。

3Thought problems1-11 In general terms what are the cellular functions of intermediate filaments, microtubules, and actin filaments?总体而言细胞中间丝，微管，微丝骨架和细胞的功能是什么？1-12 If each type of cytoskeletal filament is made up of subunits that are held together by weak noncovalent bounds, how is it possible for a human being to lift heavy objects?如果每种类型的细胞骨架丝由弱非共价键的界限，是一起举行的亚基，怎么可能一个人抬重物？1-13 A typical time course of polymerization of actin filaments from actin subunits is shown in Figure 16-1.A). Explain the properties of actin polymerization that account for each of thethree phases of the polymerization curve.B). How would the curve change if you double the concentration of actin?Would the concentration of free actin at equilibrium be higher or lower than in the original experiment, or would it be the same in both?一个典型的微丝肌动蛋白亚基的聚合过程，如图16-1所示。

A）。

解释肌动蛋白聚合的属性，为每个帐户的三个阶段的聚合曲线。

B）。

曲线会如何变化，如果你的肌动蛋白的浓度的两倍？将在平衡自由肌动蛋白的浓度会高于或低于在原有的实验，或者是在两个相同的吗？Figure 16-1 Formation of actin filaments over time, starting with purified actin monomers that are labeled with a fluorescent probe. Upon polymerization the fluorescence of the probe increases, which allows polymerization to be measured. The intensity of fluorescence at zero seconds is due to the background fluorescence of the actin monomers. The three phases of polymerization are indicated as A, B, and C.图16-1形成微丝随着时间的推移，开始用荧光探针标记与纯化的肌动蛋白单体。

聚合时的荧光探针的增加，这使得要被测量的聚合。

在零秒的荧光的强度是由于肌动蛋白单体的背景荧光。

聚合反应的三个阶段表示为A，B和C。

1-14 Phalloidiin, which is a toxic peptide form the mushroom Amanita phalloides, binds to actin filaments. Phalloidin tagged with a fluorescent probe is commonly used to stain actin filament assemblies in cells (Figure 16-14A). If phalloidin is attached to a gold particle instead, its binding to actin filament can be examined at high resolution by scanning transmission electron microscopy. Figure 16-14B shows a micrograph of an actin filament with bound phalloidin and figure 16-14c shows the same picture with the contrast adjusted so that only the points of highest intensity (the gold particles ) are visible. Does phalloidin bind to every actin subunit? How can you tell?Phalloidiin ，这是一种有毒的肽形式的蘑菇鹅膏蕈，结合肌动蛋白细丝。

是常用的荧光探针具有标记鬼笔环肽染色细胞的肌动蛋白丝组件（图16 -14A ）。

如果鬼笔环肽的金粒子，而不是连接到其绑定到肌动蛋白丝可以检查在高分辨率扫描透射电子显微镜。