The region of the cell within the membrane that includes the fluid, the cytoskeleton, and all of the organelles except the nucleus. The soluble portion of the cytoplasm, which includes molecules and small particles, such as ribosomes, but not the organelles covered with membranes.

Cytoplasm consists of all of the contents outside of the nucleus and enclosed within the cell membrane of a cell. Cytoplasm is composed mainly of water but also contains enzymes, salts, organelles, and various organic molecules.

It is generally found close to the nucleus and is the principle “traffic director” for cellular proteins. Its major function is to modify and package proteins ( sent to it by the rough ER via transport vesicles) in specific ways depending on their final destination.

It is the small, round structure in the nucleus, where ribosomes are made. Ribosomes are small grain- shaped organelles that make protein.

The primary purpose of cilia in mammalian cells is to move fluid, mucous, or cells over their surface. Cilia and flagella have the same internal structure. The major difference is in their length. Cilia and flagella move because of the interactions of a set of microtubules inside.

Cilia and flagella are alike in that they are made up of microtubules. Cilia are short, hair-like structures that exist in large numbers and usually cover the entire surface of the plasma membrane. Flagella, in contrast, are long, hair-like structures; when flagella are present, a cell has just one or two.

The only cell in the human body that has flagella is the sperm cell.

What Are Cilia and Flagella? Both prokaryotic and eukaryotic cells contain structures known as cilia and flagella. These extensions from the cell surface aid in cell movement. They also help to move substances around cells and direct the flow of substances along tracts.

In humans, for example, motile cilia are found on the respiratory epithelium lining the respiratory tract where they function in the mucociliary clearance of sweeping mucus and dirt out of the lungs. Each cell in the respiratory epithelium has around 200 motile cilia.

Cilia and Flagella Each cilium or flagellum is covered by the cell membrane and originates in the cytoplasm near a basal body, sometimes called a kinetosome. By using energy, the outer tubules move past each other, causing the organelle to bend.

Cilia are made up of microtubules coated by the plasma membrane. Each cilium comprises nine pairs of microtubules that form the outside ring and two central microtubules. This structure is called an axoneme. Cilia are attached to the cell at the basal body that is made up of microtubules arranged in nine triplets.

Cilia: The fine hairlike projections from certain cells such as those in the respiratory tract that sweep in unison and help to sweep away fluids and particles. Some single-celled organisms use the rhythmical motion of cilia for locomotion.

Cilia play an important role in locomotion. Cilia can help to remove contaminants from organs or tissue by helping to move fluids over the cell. The lining of the nasopharynx and the trachea are covered in cilia. These ciliated epithelial cells remove mucus, bacteria, and other debris from the lungs.

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.

Flagella are the organelles for bacterial locomotion. These supramolecular structures extend from the cytoplasm to the cell exterior and are composed of three major structural elements, the basal body, the hook and the filament (Fig. 1).

Types and Examples of Flagella

• Monotrichous. – Single polar flagellum. – Example: Vibrio cholerae.
• Amphitrichous. – Single flagellum on both sides. – Example: Alkaligens faecalis.
• Lophotrichous. – Tufts of flagella at one or both sides. – Example: Spirillum.
• Peritrichous. – Numerous falgella all over the bacterial body.

Flagellum, plural flagella, hairlike structure that acts primarily as an organelle of locomotion in the cells of many living organisms. Flagellar motion causes water currents necessary for respiration and circulation in sponges and coelenterates. Most motile bacteria move by means of flagella.

Flagella are composed of subunits of a low-molecular-weight protein, flagellin (20–40 kDa) arranged in a helical manner. The filamentous part of the flagellum extends outwards from the bacterial surface, and is anchored to the bacterium by its basal body.

Other relevant words (noun): flagellum, vacuole, Cilia.