Bacteria
Bacteria are single-celled prokaryotes. The genetic material in their cells is not contained in a nucleus. In addition to lacking a nucleus, the cells of bacteria also lack many other structures that are found in the cells of eukaryots. Although there are billions of bacteria on Earth, they were not discovered until the late 1600s. A Dutch merchant named Anton van Leeuwenhoek found them by accident.
The Structure Of Bacteria:
A bacteria cell contains a rigid cell wall that protects the cell, inside of the cell wall is the cell membrane, and inside the cell membrane is the cyptoplasm, which contains a gel-like material. Located in the cyptoplasm are tiny structures called ribosomes, chemical factories where proteins are produced. In the diagram, the long tentacle looking parts are called the flagella. The flagella is a long whip-like structure that helps a cell to move.
Size and Shape:
If you were to look under a microscope , you would notice that most bacterial cells have one of three basic shapes: spherical, rodlike, or spiral. The chemical makeup of a cell wall determines the shape of a bacterial cell. Bacteria also vary greatly in size. The largest known bacterium is as big as a period at the end of a sentence. An average bacterium is much smaller.
If you were to look under a microscope , you would notice that most bacterial cells have one of three basic shapes: spherical, rodlike, or spiral. The chemical makeup of a cell wall determines the shape of a bacterial cell. Bacteria also vary greatly in size. The largest known bacterium is as big as a period at the end of a sentence. An average bacterium is much smaller.
Reproduction:
When bacteria have plenty of food, the right temperature, and other suitable conditions, they thrive and reproduce frequently. Under these conditions bacteria can reproduce as often as every 20 minutes. Bacteria reproduce by a process called binary fission, in which one cell divides to form two identical cells. Binary fission is a form of asexual reproduction. Also, some bacteria may at times undergo a simple form of sexual reproduction. In a process called conjugation, which is a part of sexual reproduction, one bacterium transfers some of its genetic material to into another bacterium through a thin, threadlike bridge that joins the two cells. After the transfer, the cells separate. Conjugation does not increase the number of bacteria, however it does result in new bacteria that are genetically different from the parent cells.
When bacteria have plenty of food, the right temperature, and other suitable conditions, they thrive and reproduce frequently. Under these conditions bacteria can reproduce as often as every 20 minutes. Bacteria reproduce by a process called binary fission, in which one cell divides to form two identical cells. Binary fission is a form of asexual reproduction. Also, some bacteria may at times undergo a simple form of sexual reproduction. In a process called conjugation, which is a part of sexual reproduction, one bacterium transfers some of its genetic material to into another bacterium through a thin, threadlike bridge that joins the two cells. After the transfer, the cells separate. Conjugation does not increase the number of bacteria, however it does result in new bacteria that are genetically different from the parent cells.
Bacteria in Nature:
Bacteria are involved in oxygen and food production, environmental recycling and cleanup, and in health maintenance and medicine production. Oxygen Production: Scientists think that autotrophic bacteria were responsible for first adding oxygen to Earth's atmosphere. Food Production: Some bacteria produce the foods we like to eat while others cause food to spoil. Environmental Recycling: Also bacteria act as decomposers, organisms that break down large chemicals in dead organisms into small chemicals. Environmental Cleanup: Some bacteria help to clean up Earth's land and water. Bacteria prefer oil, so they work cleaning up oil spills in oceans and gasoline leaks in the soil under gas stations. Health and Medicine: Some bacteria help digest your food, some make vitamins that your body needs, and some compete for space with disease causing organisms. Scientists have put bacteria to work making human insulin to help the body. The human insulin is then made into medicine.
Bacteria are involved in oxygen and food production, environmental recycling and cleanup, and in health maintenance and medicine production. Oxygen Production: Scientists think that autotrophic bacteria were responsible for first adding oxygen to Earth's atmosphere. Food Production: Some bacteria produce the foods we like to eat while others cause food to spoil. Environmental Recycling: Also bacteria act as decomposers, organisms that break down large chemicals in dead organisms into small chemicals. Environmental Cleanup: Some bacteria help to clean up Earth's land and water. Bacteria prefer oil, so they work cleaning up oil spills in oceans and gasoline leaks in the soil under gas stations. Health and Medicine: Some bacteria help digest your food, some make vitamins that your body needs, and some compete for space with disease causing organisms. Scientists have put bacteria to work making human insulin to help the body. The human insulin is then made into medicine.