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Mbmizgin MB

Plasmid - Wikipedia, the free encyclopedia - 0 views

  • A plasmid is an extra-chromosomal DNA molecule separate from the chromosomal DNA which is capable of replicating independently of the chromosomal DNA.[1] In many cases, it is circular and double-stranded. Plasmids usually occur naturally in bacteria, but are sometimes found in eukaryotic organisms (e.g., the 2-micrometre-ring in Saccharomyces cerevisiae). Plasmid size varies from 1 to over 1,000 kilobase pairs (kbp).[2][3][4] The number of identical plasmids within a single cell can range anywhere from one to even thousands under some circumstances. Plasmids can be considered to be part of the mobilome, since they are often associated with conjugation, a mechanism of horizontal gene transfer.
  • Plasmids used in genetic engineering are called vectors. Plasmids serve as important tools in genetics and biotechnology labs, where they are commonly used to multiply (make many copies of) or express particular genes.[2] Many plasmids are commercially available for such uses. The gene to be replicated is inserted into copies of a plasmid containing genes that make cells resistant to particular antibiotics and a multiple cloning site (MCS, or polylinker), which is a short region containing several commonly used restriction sites allowing the easy insertion of DNA fragments at this location. Next, the plasmids are inserted into bacteria by a process called transformation. Then, the bacteria are exposed to the particular antibiotics. Only bacteria which take up copies of the plasmid survive , since the plasmid makes them resistant. In particular, the protecting genes are expressed (used to make a protein) and the expressed protein breaks down the antibiotics. In this way the antibiotics act as a filter to select only the modified bacteria
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  • Fertility-F-plasmids, which contain tra-genes. They are capable of conjugation (transfer of genetic material between bacteria which are touching). Resistance-(R)plasmids, which contain genes that can build a resistance against antibiotics or poisons and help bacteria produce pili. Historically known as R-factors, before the nature of plasmids was understood. Col-plasmids, which contain genes that code for (determine the production of) bacteriocins, proteins that can kill other bacteria. Degradative plasmids, which enable the digestion of unusual substances, e.g., toluene or salicylic acid. Virulence plasmids, which turn the bacterium into a pathogen (one that causes disease).
Mbmizgin MB

Bacterial conjugation - Wikipedia, the free encyclopedia - 0 views

  • Bacterial conjugation is often incorrectly regarded as the bacterial equivalent of sexual reproduction or mating. It is not actually sexual, as it does not involve the fusing of gametes and the creation of a zygote, nor is there equal exchange of genetic material. It is merely the transfer of genetic information from a donor cell to a recipient. In order to perform conjugation, one of the bacteria, the donor, must play host to a conjugative or mobilizable genetic element, most often a conjugative or mobilizable plasmid or transposon.[4][5] Most conjugative plasmids have systems ensuring that the recipient cell does not already contain a similar element. A transformed cell is known as a transconjugant.
tillie j

Endocytosis and Exocytosis - 0 views

  • Endocytosis is a process for moving items that are outside of the cell into the cytoplasm of the cell. Exocytosis is a process for moving items from the cytoplasm of the cell to the outside. Both endocytosis and exocytosis vary from the other forms of membrane transport, because materials do not cross through the lipid bilayer. Instead, items being moved into or out of the cell are engulfed by entire sections of the membrane lipid bilayer. They are being swallowed up or spit out by the membrane so to speak.
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    Lätt, förståelig förklaring på hur endocytos och excytos fungerar.
tillie j

Vesicle (biology) - Wikipedia, the free encyclopedia - 0 views

  • A vesicle is a bubble of liquid within a cell. More technically, a vesicle is a small, intracellular, membrane-enclosed sac that stores or transports substances within a cell. Vesicles form naturally because of the properties of lipid membranes (see micelle). Most vesicles have specialized functions depending on what materials they contain.
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    Fakta om "vesicle" - vesikel på svenska. Från wikipedia, engelska.
Zukki Jeewaratnam

ScienceDirect - Developmental Cell : Centriole Assembly Requires Both Centriolar and Pe... - 0 views

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    A text that descbribes detailed about the centriol, its structure and its function.
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    A text that descbribes detailed about the centriol, its structure and its function.
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