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Bacteria are one of the world's oldest forms of life, and are found virtually everywhere in nature. [9] Many common bacteria have plasmids, which are short, circular, self-replicating DNA molecules that are separate from the bacterial chromosome. [11]
The bright colors of Grand Prismatic Spring and Yellowstone National Park, are produced by thermophiles, a type of extremophile.. An extremophile (from Latin extremus 'extreme' and Ancient Greek φιλία (philía) 'love') is an organism that is able to live (or in some cases thrive) in extreme environments, i.e., environments with conditions approaching or stretching the limits of what known ...
The cell on the left is going through mitosis and its chromosomes have condensed. Cell nucleus: A cell's information center, the cell nucleus is the most conspicuous organelle found in a eukaryotic cell. It houses the cell's chromosomes, and is the place where almost all DNA replication and RNA synthesis (transcription) occur.
[1] [2] Historically, protozoans were regarded as "one-celled animals". When first introduced by Georg Goldfuss , in 1818, the taxon Protozoa was erected as a class within the Animalia, [ 3 ] with the word 'protozoa' meaning "first animals", because they often possess animal -like behaviours, such as motility and predation , and lack a cell ...
Any of a diverse class of small membrane-bound organelles or vesicles found in the cells of many eukaryotes, especially plants and animals, usually having some specific metabolic function and occurring in great numbers in certain specialized cell types. Peroxisomes, glyoxysomes, glycosomes, and hydrogenosomes are often considered microbodies.
Cnidaria are diploblastic animals; in other words, they have two main cell layers, while more complex animals are triploblasts having three main layers. The two main cell layers of cnidarians form epithelia that are mostly one cell thick, and are attached to a fibrous basement membrane, which they secrete.
The fertilised eggs are released by rupture of the body wall which afterwards repairs itself. As is the case in most protostomes, development of the embryo is determinate, with each cell destined to become a specific part of the animal's body. [6] At least one species of gastrotrich, Urodasys viviparus, is viviparous. [10]
The various single-cell eukaryotes were originally placed with plants or animals when they became known. In 1818, the German biologist Georg A. Goldfuss coined the word Protozoa to refer to organisms such as ciliates , [ 57 ] and this group was expanded until Ernst Haeckel made it a kingdom encompassing all single-celled eukaryotes, the ...