Exam 2 Problems - 0 1 2 3 4 5 6 7 8 9 10 11 12kb DdeI PstI...

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Unformatted text preview: 0 1 2 3 4 5 6 7 8 9 10 11 12kb DdeI PstI KpnI ClaI HindI I I KpnI SacI DdeI AluI 8kb 7kb 6kb 5kb 4kb 3kb 2kb 1kb Chapter 6 Problems C2. Conjugation is sometimes called “bacterial mating.” Is it a form of sexual reproduction? Explain. Yes and No. Conjugation can be called sexual reproduction because it involves direct physical interaction between two bacterial. The transfer of genetic material through direct physical interaction is the definition of sexual reproduction. However, I t would not be sexual reproduction since it does not involve the mixing of genomes to make gametes. Does not include two distinct parents who unite to form a new individual C9. Briefly describe the lytic and lysogenic cycles of bacteriophages. In your answer, explain what a prophage is. The lytic cycle starts with the bacteriophage injecting its DNA into the cytoplasm, then the phage DNA directs the synthesis of many new phages within the cell. The bacterial host cell bursts, releasing the newly made phages into the environment, which then can bind to new bacterial cells. The lysogenic cycle starts with a bacteriophage infects a bacterium. The bacteriophage that usually infects is called a temperate phage with do not produce new phages and will not kill the host bacterial cell. The phage then integrates its genetic material into the chromosome of the bacterium. The integrated phage DNA, called a prophage, can exist in a dormant state for a long time, during which no bacteriophages are made. When the bacterium containing a lysogenic prophage divides to produce two daughter cells, it copies the prophage’s genetic material along with its own chromosome. Thus, both daughter cells will inherit the prophage. At a later time, the prophage may become activated to excise itself to enter the lytic cell to promote the synthesis of new phages and eventually lyse the host cell. C13. Describe the steps that occur during bacterial transformation. What is a competent cell? 1. A bacterial cell dies, and when that happens, its components are fragmented. These chromosomal fragments are released into the environment. One fragment of the chromosomal DNA comes into contact, and attaches to a recipient bacterial cell 2. The recipient cell needs to be naturally competent to allow the DNA to enter the cell. Natural competence is rare and only makes up 1% of bacterial cells. To be naturally competent, the bacterium must have a hole in its cell wall. This hole will allow the DNA to go through the wall 3. The DNA must then find a way to get through the plasma membrane, and then finally inside the cell. Once it gets inside, this foreign DNA is not heritable 4. Recombination So a competent cell is one that is ready for transformation. There is also artificial competence that can be achieved in lab C14. Which bacterial genetic transfer process does not require recombination with the bacterial chromosome?...
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This note was uploaded on 12/02/2009 for the course BIO 325 taught by Professor Saxena during the Spring '08 term at University of Texas.

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Exam 2 Problems - 0 1 2 3 4 5 6 7 8 9 10 11 12kb DdeI PstI...

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