Microtubules are hollow tubes that are composed of tubulin proteins and help the cell transport materials within itself and resist shape changes.
Microtubules are the largest element (~25 nm diameter) of the cytoskeleton and commonly used by eukaryotic cells. The walls of the microtubule are made of polymerized dimers of α-tubulin and β-tubulin, two globular proteins. They help the cell resist compression, provide a track along which vesicles move through the cell, and pull replicated chromosomes to opposite ends of a dividing cell. Like microfilaments, microtubules can dissolve and reform quickly.
Microtubules also make up the structural elements of flagella and cilia, which are used to help move the entire cell or substances along the outer surface of the cell. Microtubules originate from microtubule organizing centers, like the centrosome in eukaryotic cells.
Practice Questions
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MCAT Official Prep (AAMC)
Biology Question Pack, Vol 2. Question 99
Practice Exam 2 B/B Section Passage 9 Question 51
Key Points
• Microtubules play roles in cell structure maintenance, material transport, whole cell movement, and cell division.
Key Terms
Cytoskeleton: network of protein fibers that help with cellular movement and maintaining its structure/shape
Flagellum: a lash-like appendage that protrudes from the cell body of certain prokaryotic and eukaryotic cells that help move the entire cell
Cilia: short, hair-like structures that are used to move entire cells or substances along the outer surface of the cell
Microtubule: small tubes made of protein that help cells move material around itself and resist compression
Tubulin: globular proteins that make up microtubules.
Centrosome: major microtubule organizing center, critical for mitosis