17 PROBLEM SET 8 (MCB2210 – FALL 2020) 86. Which of the following is not an example of a microtubule-organizing center (MTOC)? a. centrosome. b. flagella basal body. c. cilia basal body. d. centromere. e. all of the above. 87. All of the following are true about centrioles except a. they are the nucleating site for spindle microtubules b. they are self-replicating. c. cytoplasmic microtubules do not directly radiate from the ends of centrioles. d. they usually come in perpendicular pairs. e. they are found within animal cell centrosomes. 88. Which of the following is a function of a cilium? a. moving a cell from place to place b. moving fluid and particulate material past a cell c. a role in sensory function in monitoring the properties of extracellular material d. moving vesicles to the cell body e. all of the above 89. Which of the following is a difference between cilia and flagella? a. Flagella are usually longer than cilia. b. Cilia can be more numerous on the cell surface than flagella. c. Cilia utilize kinesin to move while flagella use dynein d. Cilia never move but flagella do e. a and b 90. Which of the following are differences between the axonemes of motile cilia/flagella and their basal bodies/centrioles? a. Basal bodies/centrioles have 9 triplet microtubules on the periphery, while cilia/flagellae axonemes have 9 doublets. b. Basal bodies/centrioles have 9 doublet microtubules on the periphery, while cilia/flagellae axonemes have triplets. c. Basal bodies/centrioles have no central microtubules, cilia/flagellae axonemes have 2 single central microtubules. d. Basal bodies/centrioles have no central microtubules, cilia/flagellae axonemes have 3 single central microtubules. e. a and c 91. Which component of the centrosome is responsible for nucleating cytoplasmic microtubules in vivo? a. The basal body b. The centriole c. The nucleus d. g - TURC e. The axoneme18 92. In an electron micrograph, an object is visible in cross-section. It appears to be made of nine sets of three hollow tubes that are fused together. They are arranged in a pattern that looks much like a pinwheel. Next to this object is a similar object oriented perpendicularly to it. What is the object in the micrograph? a. A microtubule b. A centriole c. A spindle d. A flagellum e. A cilium 93. Which of the following sites within a cell are places where microtubules are found? a. mitotic spindle b. cilium c. nucleoplasm d. a and b e. a, b and c 94. The structure that contains two barrel-shaped centrioles surrounded by amorphous, electron-dense pericentriolar material is called a(n) _________. a. centrosome b. nucleus c. pericentriosome d. spindle e. aster 95. What word below describes the arrangement of microtubules in a centriole? a. doublet b. triplet c. 9+0 d. perpendicular e. b and c 96. The outer microtubules in a motile cilium are generated directly from microtubules in a(n) _________. a. centromere b. gamma-TURC c. basal body d. PCM e. flagellum 97. The outer microtubules in a primary cilium are generated directly from microtubules in a(n) _________. a. centriole b. PCM c. centromere d. gamma-TURC e. flagellum19 98. Which of the following “organelles” are essentially equal in structure to basal bodies? a. centrioles b. microfilaments c. gamma-TURC d. centromeres e. centrosomes 99. Which of the following microtubules are the most stable polymers? a. spindle microtubules b. cytoplasmic microtubules c. microtubules undergoing catastrophe d. microtubules of cilia e. a and b 100. What is another name for motile organelles projecting from some eukaryotic cell surfaces? a. cilia b. collagen fibrils c. flagellae d. a and c e. projectosomes 101. The core of a cilium is called the ________. a. flagella b. filament c. cilioneme d. axoneme e. flagellosome 102. Which of the following true statements about cilia do we believe provides the strongest evidence that all living eukaryotes have evolved from a common ancestor? a. Cilia in different cells vary in length within a range of ~1-9µm. b. Cilia always contain microtubules c. Many eukaryotic cells use cilia for movement or creating fluid flow. d. The complex 9 + 2 pattern of axonemes is seen in a variety of organisms from protists to mammals. e. All microtubules in axonemes are oriented in the same direction. 103. Cell movement plays an important role in which of the following processes that can take place in mammals: a. Inflammation b. Wound healing c, Metastasis d. Embryonic development e. All of the above 104. Chemotaxis can be defined as a process of ___________. a) chemokine production20 b) directed cell movement toward a signal c) activated phagocytosis d) cytokine release e) blood clot formation 105. What change in the cells of the blood vessel endothelium causes the increase in adhesion of neutrophils to the surfaces of the endothelial cells in the region of the injury? a)secretion of a chemoattractant to attract the neutrophils b)display of selectins on the surface of the activated endothelial cells in the damaged area c)temporary display of integrins on the surfaces of the activated endothelial cells in the damaged area d)formation of gap junctions between the neutrophil and the endothelial cells e)no change- the change actually occurs on the neutrophil only 106. What change in the neutrophil is likely to allow it to stick tightly to the endothelium to stop rolling a)Secretion of an extracellular glue b)display of selectins on its surface c)Activation of integrin binding by phosphorylation of the cytoplasmic domain d)Activation of integrin binding by phosphorylation of the extracellular domain e)no change- the change actually occurs on the endothelium only 107. Which of the following correctly describes the sequence of adhesive changes between a leukocyte and the endothelium during inflammation a)Strong adhesions form first, mediated by selectins on leukocytes, followed by weak adhesions mediated by integrins on endothelial cells b)Weak adhesions form first, mediated by integrins on endothelial cells, followed by strong adhesions mediated by integrins on leukocytes c)Strong adhesions form first, mediated by selectins on endothelial cells, followed by weak adhesions mediated by selectins on leukocytes d)Weak adhesions form first, mediated by selectins on endothelial cells, followed by strong adhesions mediated by integrins on leukocytes e)Strong adhesions form first, mediated by integrins