This set of Cell Biology Quiz focuses on “Non-muscle Motility – 2”.
1. The Wiskott-Aldrich syndrome is caused due the lack of functional ____________ protein.
Explanation: Mammalian cells have a family of proteins (WASP/WAVE family) that activates Arp 2/3 complex at the site of stimulation near the plasma membrane. Patients of Wiscott-Aldris syndrome lack the functional WASP protein in their white blood cells.
2. Fluorescently labeled _________ can reveal the attachment sites of fibroblasts on substratum.
Explanation: Fibroblast cells help in cellular adhesion which is aided by the protein Vinculin(a cell-cell adhesion molecule that interacts with fibroblasts). A fluorescently labelled Vinculin protein is used to locate the interaction of fibroblasts.
3. Which of the following are used to study cell locomotion in fish?
Explanation: Keratocytes are cells derived from epidermal covering of fish’s scales. Locomotion is studying using keratocytes because they posses rapid gliding movement and broad lamellipodium.
4. Advancing edge of the lamellipodium is filled with actin.
Explanation: Actins are concentrated on the advancing edge of the lamellipodium because actin polymerization pushes the leading edge of a cell forward.
5. When was the first experimental evidence provided for axonal outgrowth and motility?
Explanation: Ross Harrison of Yale University performed a classic experiment in 1907 by culturing a piece of tissue from a frog’s developing nervous system. He cultured it in a tiny drop of lymphatic fluid and observed that the axons grew by a process of active outgrowth and elongation.
6. Which of the following acts as an attractant for axons?
Explanation: Advancing tip (growth cone) of a cultured neuron makes a direct turn towards a diffusible protein called netrin. It acts as an attractant for axons growing in an early embryo.
7. Changes in cell shape occur due to changes in the orientation of cytoskeletal elements.
Explanation: Cytoskeletal elements are dynamic proteins which include microfilaments, intermediate filaments and microtubules. They maintain the shape of the cell and any change in their orientation leads to change in cell shape.
8. Crawling of cells over a substratum is an example of _________________
c) nonmuscle motility
d) muscular motility
Explanation: Cells like fibroblasts and neuronal cells usually outgrow the specimen, when ultured over a substratum. This behavior is an exhibition of nonmuscle motility.
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