Test 2 selected questions

Test 2 selected questions - 23. How does a gene become a...

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23. How does a gene become a merozygote? The Hfr cell has an F factor integrated into its chromosome. The f factor (which is an episome because it can excise itself and integrate itself into the chromosomal DNA) excises itself sloppily, taking some of the chromosomal DNA along with f factor DNA. Then an endonucleases cleaves this new f’ plasmid at the origin of transfer and a conjugation bridge is made with a recipient F- cell of the same species (as recognized by the pilli’s chemical determination). The cleaved f’ plasmid will move through the conjugation bridge to the recipient cell and recircularize, and replicate to be double stranded. The recipient cell now has extra chromosomal DNA from the f’ plasmid and therefore has more genes than the typical genome making it partially diploid or a merozygote. It has a second copy of some genes that came in on the plasmid but not a second copy of all of its genes. 36. Name and explain the events characterizing two different types of transduction in bacteria There is generalized transduction and specialized transduction. In generalized transduction the phage lambda infects a bacteria cell that will end up being a donor cell and takes it through the lytic cycle. It takes over the cells machinery to replicate the lambda DNA, degrade the cell’s DNA and make capsids to package the lambda DNA. It is possible for a degraded piece of the chromosomal DNA to be the same size as the lambda DNA and happen to be packaged into a capsid and then when the cell lyses, the lambda phages will go infect other cells and the phage with the bacterial DNA
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This note was uploaded on 04/07/2008 for the course BIO 325 taught by Professor Saxena during the Spring '08 term at University of Texas at Austin.

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Test 2 selected questions - 23. How does a gene become a...

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