Learning Outcomes
i. Define cilia and flagella.
ii. Describe the structure of cilia and flagella.
iii. Explain the mechanisms of cilia and flagella movement.
iv. Discuss the significance of cilia and flagella movement for cell motility.
i. What are cilia and flagella?
Cilia and flagella are microtubule-based motile organelles that project from the cell surface. Cilia are short and numerous, while flagella are long and few in number. Cilia and flagella are found in a variety of eukaryotic cells, including protists, animal cells, and plant cells.
ii. Cilia and flagella
Structure of cilia and flagella: Cilia and flagella are made up of a bundle of microtubules called the axoneme. The axoneme is surrounded by a plasma membrane. The axoneme is made up of two central microtubules that are surrounded by nine pairs of outer microtubules. The outer microtubules are connected to each other by dynein arms.
Mechanisms of cilia and flagella movement: Cilia and flagella move by a process called sliding microtubules. The dynein arms attach to the outer microtubules and slide them relative to the central microtubules. This sliding motion causes the cilia or flagellum to bend.
iii. Cilia and flagella movement
Significance of cilia and flagella movement for cell motility: Cilia and flagella are essential for the motility of many eukaryotic cells. For example, cilia are used by some protists to move through water. Cilia are also used by animals to move mucus in the airways and to move sperm in the reproductive tract. Flagella are used by some protists to move through water and by sperm to swim to the egg.
Examples of cilia and flagella movement in action
Here are some examples of cilia and flagella movement in action:
Cilia in the airways: Cilia in the airways help to move mucus and dust particles up and out of the lungs. This helps to keep the lungs clean and free of infection.
Cilia in the reproductive tract: Cilia in the female reproductive tract help to move eggs and sperm towards each other. This is important for fertilization.
Flagella in protists: Flagella in protists help them to move through water. This is important for finding food and mates.
Flagella in sperm: Flagella in sperm help them to swim to the egg. This is important for fertilization.
Cilia and flagella are essential organelles that play a vital role in cell motility. They are found in a variety of eukaryotic cells, and they are used for a variety of purposes, such as moving mucus, moving sperm, and moving through water.