Laboratório de Tecnologia Educacional BIBLIOTECA DIGITAL               DE CIÊNCIAS

Ilustration of the major components of a bacterial cell

Physical appearance: 36 cm. The legs are short and yellow. The body is predominantly grey, darker in the back. The top of the head is black. The immature is striated and brownish. Distribution: American Continent, Africa, Asia, Australia and islands in the Pacific. Habitat: Rivers, lakes and mangroves of different sizes. Diet: Aquatic insects, mollusks, amphibians, reptiles and fish. Reproduction: The nest is a platform on the top of tall trees. Lays three eggs. Natural history: Solitary and migratory. There are saw-like structures inside the beak to help holding slippery food. May be eaten by carnivorous fish such as the trahiras (Hoplias sp.) when walking on flooded land....

35 cm. The legs and the toes are long and green. Has a red shield-like structure in the forehead that is larger in the male. The neck and inferior parts are blue. The back is brown and there is a white band in the wing. The immature individuals are brown. Distribution: All over the world, except from Australia and New Zealand. Habitat: Lives in lakes, ponds and swamps, provided there is plenty of aquatic vegetation. May be found even in very polluted places and brackish water. Diet: Feeds on vegetables and aquatic insects. Usually dives to catch the food. When it does not dive it waters the food before swallowing. Reproduction: The nest is built among the aquatic vegetation. Th...

This illustration depicts three different stages of embryonic development regarding two species: a fish and a chicken, as shown on the drawing. Fish have only the yolk sac as extra-embryonic tissue. These structures in chicken comprise, besides the yolk sac, the amniotic cavity, chorion and allantois.

Membrane Attack Complex formation through interaction of its complement system constitutive parts. The complex is typically formed on the surface of intruding pathogenic bacteria through activation of the complement system, when C5 convertase cleaves a C5 molecule into C5a and C5b. It is composed of four complement proteins (C5b, C6, C7 and C8), which bind to the outer membrane surface, and of a fifth protein, C9, polymerizing into a ring-like structure, put across the membrane and allowing free diffusion through it. This disrupts the osmotic environment of the cell and kills it promptly.