CHAPTER 13 - Ch. 13 Prokaryotes: Bacteria or Archea Always...

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Ch. 13 Prokaryotes : Bacteria or Archea Always reproduce by mitosis- they make identical clones. They still have recombination- recombination can occur. It was exhibited that DNA exchange can occur between two living bacteria. Experiment: Strain 1 E. Coli: Methoine (Met)/ Biotine (Bio) (can not grow without leu & thr.) When mixed up bacteria can now grow on medium- couldn’t grow before because it lacked essentials for growth. 1). Conjugation - mix them, can end up with bacteria that does not need Lue & Thr & Met & Bio to grow. End up with bacteria that has everything essential for growth. Exchanged genetic Will have a: Donor : give the recipient some of its DNA. Recipient : receives DNA that includes 2 wild type (+) alleles that were originally missing. The two cells must come in contact. One cell will grow an extension from it which is initialized with contact with the other cell. (Pillus- projection or extension- brings the two cells together) which eventually widens and become the conjugation tube (where transfer of DNA occurs). Met & Thr cannot grow on the medium. A chunk of DNA can be moved to other cell which is lined up = exchange or recombinant of material. Even the whole piece of DNA can move through the conjugation tube. 2). Transformation - When a cell picks up an extracellular gene and incorporates it into our DNA. 3). Transduction - When viral DNA recombines with chromosomal DNA of the host and then alters the genetic composition. During the lytic cycle, some of the host DNA gets packaged into the viral capside or into the viral protein coat. So when the virus goes to infect another cell, it
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will carry a segment of the cells DNA. The previous cell DNA is incorporated into the new host 4). Transfer of a plasmid - The plasmid, is a very small extracellular piece of DNA which has its own origin of replication. (ori). Plasmids can carry multiple genes. The genes they carry referred to as factors (R- factors). Ex). Antibiotic resistant. Ex) carries gene that code for enzymes that break down hydrocarbons so it can use the carbons. The fertility factors- cells that have to come in contact to form pillus but must have the right fertility factors. Makes conjugation tube and pillus. (genes encoded for conjugation). Metabolic factors- all chemical reactions in a body. 5). Transposable elements - (jumping genes)- When a segment of a chromosome or plasmid can insert itself into a new location. Can redesign gene Most of the time the gene becomes disrupted. They remove or copy themselves from genome and re-insert itself in another
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This note was uploaded on 09/17/2009 for the course BIO 120 taught by Professor Ander... during the Fall '08 term at Detroit Mercy.

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CHAPTER 13 - Ch. 13 Prokaryotes: Bacteria or Archea Always...

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