Microbiology is the scientific discipline focused on the study of microorganisms and of the effects they may have on other organisms. The term derives from the Greek words mīkros (meaning small), bios (meaning life), and logia (meaning study of). Generally, microorganisms are too small to be seen with the unaided eye. Microbiologists, scientists studying these small organisms, aid their observations with the use of such devices as microscopes (optical and electronic) and hand lenses.
Such organisms as bacteria, viruses, some algae and protozoa, and prions fall within the definition of microorganisms. Microorganisms constitute the majority of organisms; yet, only a very small percentage of the Earth's microbial species, populations and communities have been characterized scientifically.
Centers for Disease Control and Prevention
Yellow fever is a viral disease that is transmitted to humans...
FungiLast Updated on 2014-08-28 00:25:51The word fungus usually invokes images of mushrooms and toadstools. Although mushrooms are fungi, the forms which a fungus may take are varied. There are over 100,000 species of described fungi and probably over 200,000 undescribed.
Most fungi are terrestrial, but they can be found in every habitat worldwide, including marine (500 spp.) and freshwater environments. Fungi are nonmotile, filamentous eukaryotes that lack plastids and photosynthetic pigments. The majority of fungi are saprophytes; they obtain nutrients from dead organic matter. Other fungi survive as parasitic decomposers, absorbing their food, in solution, through their cell walls.
Most fungi live on the substrate upon which they feed. Numerous hyphae penetrate the wood, cheese, soil, or flesh in which they are growing. The hyphae secrete digestive enzymes that break down the substrate, enabling the fungus to absorb the... More »
CellsLast Updated on 2014-06-30 14:15:10
Cells are the smallest component of the body that can perform all of the basic life functions. Each cell performs specialized functions and plays a role in the maintenance of homeostasis. While each cell is an independent entity, it is highly affected by damage to neighboring cells. These various cell types combine to form tissues, which are basically collections of specialized cells that perform a relatively limited number of functions specific to that type of tissue. The human body is made up of several trillion cells; these cells are of various types, which can differ greatly in size, appearance and function.
While there are approximately 200 types of cells, they all have similar features: cell membrane, cytoplasm, organelles, and nucleus. The only exception is that the mature red blood cell does not contain a nucleus. In general, toxins can injure any of the components of... More »
Composting tipsLast Updated on 2014-06-29 18:07:28
Composting turns household wastes into valuable fertilizer and soil organic matter.
All organic matter eventually decomposes. Composting speeds the process by providing an ideal environment for bacteria and other decomposing microorganisms. The final product, humus or compost, looks and feels like fertile garden soil. This dark, crumbly, earthy-smelling stuff works wonders on all kinds of soil and provides vital nutrients to help plants grow and look better.
Decomposing organisms consist of bacteria, fungi, and larger organisms such as worms, sow bugs, nematodes, and numerous others. Decomposing organisms need four key elements to thrive: nitrogen, carbon, moisture, and oxygen. For best results, mix materials high in nitrogen (such as clover, fresh grass clippings, and livestock manure) and those high in carbon (such as dried leaves and twigs). If there is not a good supply of... More »
Marine microbesLast Updated on 2014-06-18 17:12:26
The term 'Marine microbes' encompasses all microscopic organisms generally found in saltwater. Most micro-organisms are acellular and fall into the major categories of viruses, prokaryotes ('bacteria'), and protists, groups which differ considerably in biological characteristics. While representatives of these groups are found in virtually everywhere in marine waters and they play nearly every ecological role imaginable, their most important function is that they form the base of the food chain in marine ecosystems.
Well-known to us as disease-causing agents, viruses are deceivingly simple organisms, little more than some nucleic acid within a protein container. They are 'parasitic particles' most about 40 nanometers in size. Viruses attach themselves to a living cell and inject a bit of nucleic acid into the cell; the injected nucleic acid... More »
Arctic marine environmentsLast Updated on 2014-06-18 16:42:07
This is Section 10.2.1 of the Arctic Climate Impact Assessment
Lead Author: Michael B. Usher; Contributing Authors:Terry V. Callaghan, Grant Gilchrist, Bill Heal, Glenn P. Juday, Harald Loeng, Magdalena A. K. Muir, Pål Prestrud
The arctic marine environment covers about 13 million km2, of which about 45% is a permanent ice cap that covers part of the Arctic Ocean. Seasonal sea ice forms during winter, and recedes during the short arctic summer, exposing large areas of open water. The marine environment is thus dominated by sea ice and by the dynamics of that ice and especially the location of the ice edge. The transition zone between the sea ice and the open water has intense algal growth in spring and summer, and it is the primary production by these phytoplankton that supports the arctic marine food webs. Only in exceptional cases can the energy that drives the marine food... More »
Drag and drop the content to change the order of featured content. The top nine will be displayed.