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MCAT Content / Cytoskeleton / Microtubules Composition And Role In Support And Transport

Microtubules: composition and role in support and transport

Topic: Cytoskeleton


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


Khan Academy

MCAT Official Prep (AAMC)

Biology Question Pack, Vol 2. Question 99

Practice Exam 2 B/B Section Passage 9 Question 51

Key Points

• Microtubules are hollow tubes that are made of dimers of the proteins α-tubulin and β-tubulin.

• 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

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