Wednesday, March 11, 2009

Bacteria and Viruses

Bacteria are single celled prokaryotic organisms. Bacteria have one of three basic shapes: spherical, rodlike or spiral.

When bacteria have plenty of food, the right temperature, and other suitable conditions, they thrive and reproduce frequently.

Bacteria reproduce by binary fission, a process in which one cell divides to form two identical cells. Binary fission is a form of asexual reproduction. Asexual reproduction is a reproductive process that involves only one parent and produces offspring that are identical to the parent. Sexual reproduction involves two parents who combine genetic material to produce a new organism that is different from both parents. Some bacteria perform a simple form of sexual reproduction called conjugation. In conjugation, one bacterium transfers some of its genetic material into another bacterium.

Many bacteria can survie harsh conditions by forming edospores.

Bacteria are involved in oxygen and food production, environmental recycleing and cleanup, and health maintenance and medicine production.

A virus is a tiny, nonliving particle that enters and then reproduces inside a living cell. The organism that a virus enters and multiplies inside is called a host. Viruses are smaller than cells and vary in shape and size.

All viruses have two basic parts: a protein coat that protects the virus and an inner core made of genetic material. After a virus attaches to a host cell, it enters the cell. Once inside a cell, a virus' genetic material takes over many of the cell's functions. It instructs the cell to produce the virus' proteins and gentic material. These proteins and gentic material then assemble into new viruses.

An active virus immediately takes over the cell's functions, and uses them to produce the virus' protein and gentic material. When the host cell is full of new viruses, it bursts open and releases the new viruses.