In molecular biology transformation is the genetic alteration of a cell resulting from the direct uptake, incorporation and expression of exogenous genetic material (exogenous DNA) from its surrounding and taken up through the cell membrane(s). Transformation occurs most commonly in bacteria and in some species occurs naturally. Transformation can also be effected by artificial means. Bacteria that are capable of being transformed, whether naturally or artificially, are called competent. Transformation is one of three processes by which exogenous genetic material may be introduced into a bacterial cell, the other two being conjugation (transfer of genetic material between two bacterial cells in direct contact), and transduction (injection of foreign DNA by a bacteriophage virus into the host bacterium). Transformation may also be used to describe the insertion of new genetic material into nonbacterial cells including animal and plant cells; however, because "transformation" has a special meaning in relation to animal cells, indicating progression to a cancerous state, the term should be avoided for animal cells when describing introduction of exogenous genetic material. Introduction of foreign DNA into eukaryotic cells is usually called "transfection".[1]
Wednesday, 14 September 2011
Saturday, 3 September 2011
a bacteria turns carbon to food
A bacteria turns carbon to food?
Scientists have identified some mysterious organisms in the dark depths of the ocean which they believe are converting carbon dioxide into a form useful for life. The bugs, which the scientists call “twilight” microbes, could be the missing link of global carbon cycle as they are found turning inorganic carbon into useable food some 2,625 feet below the ocean surface.
The job of capturing carbon — crucial to sustaining life on earth — is usually carried out by plants that use sunlight as energy. But light doesn’t penetrate below 656 feet of ocean, so plants can’t do this job. To survive, living cells must convert carbon dioxide into molecules that can form cellular structures or be used in metabolic processes, the scientists said.
Simple, single-celled organisms called archaea that often live in extreme conditions were thought to be responsible for much of the dark ocean’s carbon fixation. But there was evidence that archaea could not account for the total amount of carbon fixation going on there.
“Our study discovered specific types of bacteria, rather than archaea, and their likely energy sources that may be responsible for this major, unaccounted component of the dark ocean carbon cycle,” said study author Ramunas Stepanauskas of the Bigelow Laboratory Single Cell Genomics Center in the Gulf of Maine. To get a glimpse of what was going on in the dark, the researchers looked at samples from two subtropical gyres, or systems of rotating ocean currents, in the South Atlantic and North Pacific.
The job of capturing carbon — crucial to sustaining life on earth — is usually carried out by plants that use sunlight as energy. But light doesn’t penetrate below 656 feet of ocean, so plants can’t do this job. To survive, living cells must convert carbon dioxide into molecules that can form cellular structures or be used in metabolic processes, the scientists said.
Simple, single-celled organisms called archaea that often live in extreme conditions were thought to be responsible for much of the dark ocean’s carbon fixation. But there was evidence that archaea could not account for the total amount of carbon fixation going on there.
“Our study discovered specific types of bacteria, rather than archaea, and their likely energy sources that may be responsible for this major, unaccounted component of the dark ocean carbon cycle,” said study author Ramunas Stepanauskas of the Bigelow Laboratory Single Cell Genomics Center in the Gulf of Maine. To get a glimpse of what was going on in the dark, the researchers looked at samples from two subtropical gyres, or systems of rotating ocean currents, in the South Atlantic and North Pacific.
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