Appendage

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A beetle leg

An appendage (or outgrowth) is an external body part, or natural prolongation, that protrudes from an organism's or microorganism's body.

Types in animals

In

sexual organs (gonopods), and parts of the tail (uropods). Typically, each body segment carries one pair of appendages. An appendage which is modified to assist in feeding is known as a maxilliped or gnathopod.[citation needed
]

In

]

Appendages may become uniramous, as in insects and centipedes, where each appendage comprises a single series of segments, or it may be biramous, as in many crustaceans, where each appendage branches into two sections. Triramous (branching into three) appendages are also possible.[1]

All arthropod appendages are variations of the same basic structure (homologous), and which structure is produced is controlled by "homeobox" genes. Changes to these genes have allowed scientists to produce animals (chiefly Drosophila melanogaster) with modified appendages, such as legs instead of antennae.[2]

Types in prokaryotes

A number of cell surface appendages are found in

flagella, pili, and prosthecae
also called stalks.

Archaea

A number of surface appendages may be present on different archaea. Two types of appendage are species-specific;

archaella (archaeal flagella), structures called bindisomes that bind sugars, and posttranslationally modified archaellins and pilins.[4][5]

Archaella are the similar structures to bacterial flagella with the same function in motility particularly swimming, but with a different composition and action. Pili are used in attachment to surfaces, possible communication between cells enabling cell to cell contact allowing genetic transfer, and the formation of

Bacteria

Bacterial surface appendages include

fimbriae, and on some species curli fibres
. Some bacteria also have stalks known as
prosthecae
.

Types in plants

A leaf is the main appendage of a plant stem. Prosthechea is a genus of orchids named for the prostheca appendage on the back of the column. Hair like structures known as trichomes are found on many types of plants.

References

See also