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Old 12-23-2012
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Bacteria The Repressor in Bacterial Specialized Transduction

What is a repressor in the specialized transduction, the author is talking about?
page 326 Kaplan Lecture Notes

Please help
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Old 12-24-2012
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A bacteriophage can either be a Lytic phage where it multiplies many folds & ultimately ruptures the bacteria to come out OR it can be a Temperate phage where it stops multiplying & integrates with bacterial DNA.

A repressor protein helps the phage to stop its replication in Lysogenic/ Temperate cycle so that it does not lyse the cell & instead gets integrated with bacterial DNA. If the repressor protein is absent or mutated, then the Phage continues its replication & very soon lyses the bacterial cell & does not get a chance of integrating its DNA into the bacterial DNA.

Hope this clears your doubt...
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Old 12-24-2012
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Quote:
Originally Posted by docsdr View Post
A bacteriophage can either be a Lytic phage where it multiplies many folds & ultimately ruptures the bacteria to come out OR it can be a Temperate phage where it stops multiplying & integrates with bacterial DNA.

A repressor protein helps the phage to stop its replication in Lysogenic/ Temperate cycle so that it does not lyse the cell & instead gets integrated with bacterial DNA. If the repressor protein is absent or mutated, then the Phage continues its replication & very soon lyses the bacterial cell & does not get a chance of integrating its DNA into the bacterial DNA.

Hope this clears your doubt...
Yeah, just curious now that where is this repressor coming from?
I think may be its the bacterial cell, but is it already there or programed by the phage?
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Old 12-24-2012
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Quote:
Originally Posted by aliawn88 View Post
yeah , just curious now that whr is this repressor coming from?
i think may be its the bacterial cell , but is it already there or programed by the phage?
The repressor protein comes with the Phage itself. It is actually encoded for in the phage genome. On entering the bacteria, expression of the phage genome results in formation of Repressor protein.

Actually there are 2 proteins "Repressor" & "Cro" which are coded in phage genome. Expression of phage genome results in formation of respective proteins. A competition between the cro and repressor proteins determines whether the phage embarks on a lytic or lysogenic lifecycle.

Repressor and cro compete for control of an operator region containing three operators that determine the state of the lytic/lysogenic genetic switch.

If this competition is won by repressor, transcription of the cro gene is blocked and repressor transcription is maintained. Lysogeny will result.

A competition won by cro, however, means that the late genes of phage l will be expressed; this will result in lysis.
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Old 12-24-2012
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Quote:
Originally Posted by docsdr View Post
The repressor protein comes with the Phage itself. It is actually encoded for in the phage genome. On entering the bacteria, expression of the phage genome results in formation of Repressor protein.

Actually there are 2 proteins "Repressor" & "Cro" which are coded in phage genome. Expression of phage genome results in formation of respective proteins. A competition between the cro and repressor proteins determines whether the phage embarks on a lytic or lysogenic lifecycle.

Repressor and cro compete for control of an operator region containing three operators that determine the state of the lytic/lysogenic genetic switch.

If this competition is won by repressor, transcription of the cro gene is blocked and repressor transcription is maintained. Lysogeny will result.

A competition won by cro, however, means that the late genes of phage l will be expressed; this will result in lysis.

thanks alot , now its pretty much clear, thanx for your tym
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Old 12-24-2012
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Quote:
Originally Posted by aliawn88 View Post
thanks alot , now its pretty much clear, thanx for your tym
U r welcome my friend... i just finished reading Micro, thatswhy i could answer ...
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