Cilia and flagella

Dianne Dotson; Updated September 10, Cilia and flagella are two different types of microscopic appendages on cells. Cilia are found in both animals and micro-organisms, but not in most plants.

Cilia and flagella

Cilia and Flagella Cilia and flagella are motile cellular appendages found in most microorganisms and animals, but not in higher plants. In multicellular organisms, cilia function to move a cell or group of cells or to help transport fluid or materials past them.

The respiratory tract in humans is lined with cilia that keep inhaled dust, smog, and potentially harmful microorganisms from entering the lungs. Among other tasks, cilia also generate water currents to carry food and oxygen past the gills of clams and transport food through the digestive systems of snails.

Flagella are found primarily on gametes, but create the water currents necessary for respiration and circulation in sponges and coelenterates as well. For single-celled eukaryotes, cilia and flagella are essential for the locomotion of individual organisms.

Protozoans belonging to the phylum Ciliophora Cilia and flagella covered with cilia, while flagella are a characteristic of the protozoan group Mastigophora. In eukaryotic cells, cilia and flagella contain the motor protein dynein and microtubules, which are composed of linear polymers of globular proteins called tubulin.

The core of each of the structures is termed the axoneme and contains two central microtubules that are surrounded by an outer ring of nine doublet microtubules.

Molecular Expressions Cell Biology: Animal Cell Structure - Cilia and Flagella

One full microtubule and one partial microtubule, the latter of which shares a tubule wall with the other microtubule, comprise each doublet microtubule see Figure 1. Dynein molecules are located around the circumference of the axoneme at regular intervals along its length where they bridge the gaps between adjacent microtubule doublets.

A plasma membrane surrounds the entire axoneme complex, which is attached to the cell at a structure termed the basal body also known as a kinetosome.

Basal bodies maintain the basic outer ring structure of the axoneme, but each of the nine sets of circumferential filaments is composed of three microtubules, rather than a doublet of microtubules. Thus, the basal body is structurally identical to the centrioles that are found in the centrosome located near the nucleus of the cell.

In some organisms, such as the unicellular Chlamydomonas, basal bodies are locationally and functionally altered into centrioles and their flagella resorbed before cell division. Eukaryotic cilia and flagella are generally differentiated based on size and number: The structures also exhibit somewhat different types of motion, though in both cases movement is generated by the activation of dynein and the resultant bending of the axoneme.


The movement of cilia is often described as whip-like, or compared to the breast stroke in swimming. Adjacent cilia move almost simultaneously but not quiteso that in groups of cilia, wave-like patterns of motion occur. Flagella, however, exhibit a smooth, independent undulatory type of movement in eukaryotes.

Prokaryotic flagella, which have a completely different structure built from the protein flagellin, move in a rotating fashion powered by the basal motor. Defects in the cilia and flagella of human cells are associated with some notable medical problems. The disease also results in male sterility due to the inability of sperm cells to propel themselves via flagella.

Damage to respiratory cilia may also be acquired rather than inherited and is most commonly linked to smoking cigarettes. Bronchitis, for instance, is often triggered by a build-up of mucus and tar in the lungs that cannot be properly removed due to smoking-related impairment of cilia.

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Use of this website means you agree to all of the Legal Terms and Conditions set forth by the owners.Cilia and flagella have a core composed of microtubules that are connected to the plasma membrane and arranged in what is known as a 9 + 2 pattern.

The pattern is so named because it consists of a ring of nine microtubule paired sets (doublets) that encircle two singular microtubules. Cilia and flagella are two types of organelles that bear similarities in motility. Cilia are smaller, grouped appendages found in micro-organisms and plants.

Flagella are found in bacteria as well as in eukaryotes. While motility are key functions, cilia and flagella possess many other functions. Nov 28,  · Cilia and flagella are auxiliary parts of living cells.

Cilia help in preventing accumulation of dust in breathing tubes by creating a thin layer of mucous along the tubes. Flagella are mainly used by sperm cells to propel themselves through the female reproductive organ.

A multitude of living /5(8). Cilia and flagella are motile cellular appendages found in most microorganisms and animals, but not in higher plants. In multicellular organisms, cilia function to move a cell or group of cells or to help transport fluid or materials past them.

Cilia and flagella

The respiratory tract in humans is lined with cilia. Cilia and flagella are cell organelles that are structurally similar but are differentiated based on their function and/or length. Cilia are short and there are usually many (hundreds) cilia per cell.

Cilia and flagella

On the other hand, flagella are longer and there are fewer flagella per cell (usually one to eight). A flagellum (/ f l ə ˈ dʒ ɛ l əm /; plural: flagella) is a lash-like appendage that protrudes from the cell body of certain bacterial and eukaryotic cells.

The primary role of the flagellum is locomotion, but it also often has function as a sensory organelle, being sensitive to chemicals and temperatures outside the cell. The similar structure in the archaea functions in the same way but FMA:

Cilia, flagella, and centrioles | Celebrate Cytochemistry | Gwen V. Childs, Ph.D.