Microtubules often produce movement through their interaction with motor proteins. But in some cases, microtubules move cell components when the length of the microtubule changes. Through a series of experiments, researchers determined that microtubules grow and shorten as tubulin proteins are added or removed from their ends. Other experiments showed that microtubules make up the spindle apparatus that 'pulls' chromosomes toward opposite ends (poles) of a dividing cell. The figures below describe a clever experiment done in 1987 to determine whether a spindle microtubule shortens (depolymerizes) at the end holding a chromosome or at the pole end of a dividing cell. Experimenters labeled the microtubules of a dividing cell from a pig kidney with a yellow fluorescent dye. As shown on the left half of the diagram below, they then marked a region halfway along the microtubules by using a laser to eliminate the fluorescence from that region. They did not mark the other side of the spindle (right side of the figure).
5. Cell Components
Introduction to the Cytoskeleton
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Join thousands of students who trust us to help them ace their exams!Watch the first videoMultiple Choice
Bacterial cytoskeleton proteins share ancestry with which two eukaryotic proteins?
A
Fibronectin and laminin
B
Keratin and myosin
C
Collagen and elastin
D
Actin and tubulin
Verified step by step guidance1
Understand that the cytoskeleton is a structure that helps cells maintain their shape and internal organization, and it is involved in various cellular processes such as division and movement.
Recognize that in eukaryotic cells, the cytoskeleton is primarily composed of three types of protein filaments: microfilaments, intermediate filaments, and microtubules.
Identify that actin is a protein that forms microfilaments, which are involved in cell movement and shape changes, and is a key component of the eukaryotic cytoskeleton.
Identify that tubulin is a protein that forms microtubules, which are involved in maintaining cell shape, enabling intracellular transport, and facilitating cell division, and is another key component of the eukaryotic cytoskeleton.
Conclude that bacterial cytoskeleton proteins share ancestry with actin and tubulin, as these proteins are fundamental to the structure and function of the cytoskeleton in both prokaryotic and eukaryotic cells.
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