Table of contents

1. Overview of Cell Biology2h 49m
2. Chemical Components of Cells1h 14m
3. Energy1h 33m
4. DNA, Chromosomes, and Genomes2h 31m
5. DNA to RNA to Protein2h 31m
6. Proteins1h 36m
7. Gene Expression1h 42m
8. Membrane Structure1h 4m
- The Lipid Bilayer
  38m
- Membrane Proteins
  25m
9. Transport Across Membranes1h 52m
10. Anerobic Respiration1h 5m
11. Aerobic Respiration1h 11m
12. Photosynthesis52m
13. Intracellular Protein Transport2h 18m
14. Cell Signaling1h 28m
15. Cytoskeleton and Cell Movement1h 39m
16. Cell Division3h 5m
17. Meiosis and Sexual Reproduction50m
18. Cell Junctions and Tissues48m
19. Stem Cells13m
- Stem Cells
  13m
20. Cancer44m
21. The Immune System1h 6m
22. Techniques in Cell Biology1h 41m

15. Cytoskeleton and Cell Movement

Cilia and Flagella

Cell Biology

15. Cytoskeleton and Cell Movement

Cilia and Flagella

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Multiple Choice

Cilia and flagella bend because of _____.

the synthesis of new microtubules

the contraction of actin filaments

the sliding of microtubule doublets driven by dynein motor proteins

the influx of calcium ions

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Verified step by step guidance

Understand the structure of cilia and flagella: Both cilia and flagella are composed of a core structure called the axoneme, which contains microtubule doublets arranged in a '9+2' pattern (nine outer doublets surrounding two central microtubules).

Recognize the role of dynein motor proteins: Dynein is a motor protein that attaches to one microtubule doublet and 'walks' along the adjacent doublet using ATP as an energy source. This movement generates force.

Explain the sliding mechanism: The dynein-driven movement causes the microtubule doublets to slide relative to each other. However, because the microtubules are anchored by other proteins, this sliding is converted into bending.

Clarify why other options are incorrect: The synthesis of new microtubules is not involved in the bending process, and the contraction of actin filaments is unrelated to cilia and flagella movement. Similarly, the influx of calcium ions is not the primary driver of bending.

Conclude that the bending of cilia and flagella is due to the sliding of microtubule doublets driven by dynein motor proteins, which is the correct answer.