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Bacterial Genetics and Replication

1. See the attached file for a diagram of DNA that can serve as template for replication. Label the origin. Using a circle to represent the polymerase, diagram the leading and lagging strands, indicating the direction of synthesis. Be sure to completely label the new DNA.

2. You have 2 tubes containing cultures of genetically distinct bacterial strains. You know that when you mix the two together, you get Horizontal gene transfer (HGT), but you do not know what genetic exchange mechanism is accomplishing this transfer. Prior to mixing the strains, you add an enzyme that degrades any DNA it comes into contact with the tubes and allow it to incubate briefly. You then mix contents of both tubes together and find that you are no longer able to achieve HGT. Both cultures are still completely viable. Name the 3 methods of HGT that we discussed in class. Which of these is the MOST likely process you interfered with? In your answer, explain your observations and why the other two processes are not likely to be involved.

3. Below is a sequence of double stranded DNA from a bacterium. Based on what you know about bacterial transcription and translation, put an "X" next to the strand that is most likely to be the template strand for transcription and give a brief answer for your choice (5-10 words). Then,
clearly underline the likely coding sequence
transcribe it into mRNA
C) translate this into protein using the genetic code table.

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Section A: General Bacterial Genetics
1. See the attached file for a diagram of DNA that can serve as template for replication. Label the origin. Using a circle to represent the polymerase, diagram the leading and lagging strands, indicating the direction of synthesis. Be sure to completely label the new DNA.

Origin of replicationn- bacteria have only one origin of replication. (1) DNA replication occur in a bidirectional direction from the origin of replication.(1) Starting from the origin of replication, replication proceeds in opposite directions away from origin. (1) Two replication forks from each origin of replication occur because replication is bi-directional. (1) The open area of chromosome between replication forks is called replication bubble.
DNA polymerases catalyzed DNA replication. (1) DNA polymerase synthesize DNA only in the 5' to 3' direction. (1) DNA pol I need a primer to initiate DNA replication. (1) A primer is a preexisting nucleic acid that initiate DNA synthesis. (1) DNA polymerase need to add nucleotide to the 3' end free hydroxyl group. (1) DNA polymeras II and III are the main polymerase for DNA replication. (1) DNA pol I is mainly involve in DNA repair. (1)

DNA pol III start to add nucleotide to the new DNA strand. As the replication fork unwind, synthesis of one strand ( lower strand) continue following the replication fork. (1) The other strand cannot continue to move along, but leave a gap behind. A second RNA primer is needed to complete the DNA synthesis. (1) Thus, at each replication fork, the synthesis of new DNA strand ( lower strand) is continuous, while the synthesis of the other strand is discontinuous. (1) The strand of DNA that is synthesize continuously is the leading strand and the discontinuous synthesized strand is the lagging strand. (1) Small fragments of DNA of the lagging strand are ...

Solution Summary

Bacteria are small, microscopic organisms that have a unique, but simple replication process. Unlike eukaryotes that have multiple origins of replication, bacteria have only one origin of replication. Bacteria's DNA replication occur in a bidirectional way from the origin of replication. Starting from the origin, replication occur in opposite direction. There are two replication forks from each origin occur because replication is bidirectional. DNA polymerase catalyze the addition of new strands. There are also three kinds of genetic transfer in the bacteria. The type of gene transfer processes are transduction, transformation, and conjugation.

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