Importance of microorganisms to humankind 21
antibiotics, and other pharmaceuticals that are used to prevent or to treat many human diseases are microbial products.
Many microorganisms benefit humans, producing foods we eat, removing wastes we produce, and making antibiotics and vaccines for use in medicine.
Many agricultural practices encourage the beneficial metabolic activities of microorganisms and discourage their harmful effects. Spacing of crops, the development of disease resistant plant varieties, and the use of chemical pesticides aim to limit infections due to plant pathogens. They also limit crop damage due to insects and other nonmicrobial pests. Crop rotation uses plants such as alfalfa and soybeans that are associated with nitrogen-fixing bacteria. These bacteria can convert atmospheric nitrogen (N2) into forms of nitrogen that can be used by plants. Plant growth depends on the forms of nitrogen provided by these bacteria or on the addition of nitrogen fertilizers by farmers. Without the microbial activities that transform decaying dead material to substances that can be reused by the living, life on earth would soon cease. We could not survive without microorganisms.
Microorganisms are essential for maintaining the balance of nature and sustaining life on earth.
Clearly the microorganisms are complex and difficult to understand — powerful but small, necessary yet sometimes deadly. Through the science of micro-
BiOTECHNOLOGY TO CURE GLOBAL WARMING
Microorganisms may have a role in reversing global warming. They may be used to remove carbon dioxide from the atmosphere. Japanese researchers are investigating the possibility of using genetically engineered algae to remove carbon dioxide from the atmosphere and maintain levels of atmospheric carbon dioxide that will not cause global warming. Already, Japanese researchers have found an alga that has ten times the carbon dioxide fixing capacity of trees. This would be a novel employment of biotechnology for the maintenance of global environmental quality. The idea is to genetically engineer algae with high photosynthetic capacities that produce polymers that are not easily biodegraded. In this way, carbon dioxide would be drawn out of the atmosphere and incorporated into compounds that are not easily degraded back to carbon dioxide.
biology we have increased standards of living, improved agricultural crop yields, helped maintain environmental quality, and decreased the incidence of disease. By studying the microorganisms, we hope to develop the necessary understanding to control microorganisms for the benefit of the future of humankind.
FIG. 1-11 cont'd C, Some vaccines are produced by growing recombinant vaccine strains in fermentors; the fermentor in this photograph is used to produce hepatitis В vaccine employing a recombinant strain of Escherichia coli containing the viral genes.
SUMMARY
Microorganisms (pp. 3-13)
Microorganisms are very small life forms.
The observation of microorganisms depends on the use of microscopes.
Antonie van Leeuwenhoek made the first recorded microscopic observations of bacteria.
The Organizational Structure of Microorganisms (pp. 5-13)
Even microorganisms, the smallest forms of life, are highly organized living systems.
The cell is the fundamental unit of all living systems.
The plasma membrane acts as a barrier that controls the flow of material into and out of the cell.
Cells contain hereditary information in DNA and carry out metabolism that transforms energy and materials.
Many microorganisms are unicellular (single celled organisms).
Some microorganisms are multicellular (composed of many cells).
Bacteria are cellular organisms, with simple cells that lack organelles.
Bacterial cells are prokaryotic.
Fungi, algae, protozoa, plants, and animals (including humans) all have eukaryotic cells.
Eukaryotic cells have organelles, including a nucleus that houses the genetic information.
Organelles are membrane-bound compartments within a cell.
Viruses are not made of cells.
Viruses only replicate within living cells.