Cell biologyLesson 3 of 4 in the course Cell Structure

Cytoskeletal Filaments: Actin, Intermediate Filaments, and Microtubules

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

The cytoskeleton is an internal network of protein fibers that helps cells maintain their shape, organize their contents, and move materials or the cell itself. This lesson introduces the cytoskeleton and examines its two smaller fiber types: microfilaments and intermediate filaments.

The cytoskeleton is not a rigid, permanent scaffold. Its fibers can be assembled, disassembled, and reorganized, allowing cells to adapt their structure and activity. The three main types are microfilaments, intermediate filaments, and microtubules.

All flashcards

What roles does the cytoskeleton perform in cells?
It helps maintain cell shape, position some organelles, move materials, and enable cell movement.
How are intermediate filaments built?
Several strands of fibrous proteins are wound together to form fibers about 8–10 nm wide.
What are microtubules made of?
They are hollow tubes built from repeating dimers of α-tubulin and β-tubulin.
How do cilia and flagella typically differ?
Flagella are generally long and few; cilia are shorter and often numerous.
What does the eukaryotic 9 + 2 arrangement describe?
Nine outer microtubule doublets surrounding two central microtubules in many cilia and flagella.

Quiz questions

  1. How do actin and myosin contribute to muscle contraction?Answer: Their filaments slide past one another, causing the muscle to contract.
  2. What is the name for a cell engulfing material such as a pathogen?Answer: Phagocytosis.
  3. What is the approximate diameter and main protein of a microfilament?Answer: About 7 nm; actin.
  4. In animal cells, which structure organizes microtubules and contains two perpendicular centrioles?Answer: The centrosome.
  5. During cell division, what do microtubules help do with replicated chromosomes?Answer: Move them toward opposite ends of the dividing cell.

Based on Biology 2e by Mary Ann Clark, Matthew Douglas, Jung Choi (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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