Daily Newsletter January 23, 2012
Today's Topic:Bacterial DNA Replication
The bacterial genophore (molecule of DNA) is generally circular, but there are some examples where you find linear molecules of DNA (Agrobacterium and Borrella are two examples with linear DNA). The bacterial genome, which is the total of all DNA molecules in the cell, consists of the genophore (the core DNA molecule equivalent to a eukaryote's chromosome) and plasmids.
DNA must replicate during cellular division so that each daughter cell can have the parental genetic information. The genophore is always replicated, but there are examples of non-replicating plasmids. In the case of a non-replicating plasmid, only one daughter cell will get the plasmid.
NOTE: Why do we not use the phrase Bacterial Chromosome? Many people use it, including microbiologists. It is an easy phrase, and immediately brings up to your mind the idea of the main genetic units of a cell, but what is a chromosome? A chromosome, by definition, is made of chromatin. These are the individual molecules of supercoiled DNA that appear only during Mitosis. Bacteria do not produce chromatin, and they do not undergo mitosis. Thus, they do not have a true chromosome. The term genophore, coined by Hans Ris, is thought of as a gene holding unit, or a unit of genetic linkages, i.e., a molecule of DNA. So, we should discuss the Bacterial Genophore, not the bacterial chromosome.
Daily Challenge: Bacterial Replication
Provide a brief review of replication (emphasis on brief). The focus of your work today should be on distinguishing the elements of bacterial replication that are different from eukaryotic replication. Specifically, what challenges or advantages do most bacteria have when it comes to replication?
The bacterial genophore (molecule of DNA) is generally circular, but there are some examples where you find linear molecules of DNA (Agrobacterium and Borrella are two examples with linear DNA). The bacterial genome, which is the total of all DNA molecules in the cell, consists of the genophore (the core DNA molecule equivalent to a eukaryote's chromosome) and plasmids.
DNA must replicate during cellular division so that each daughter cell can have the parental genetic information. The genophore is always replicated, but there are examples of non-replicating plasmids. In the case of a non-replicating plasmid, only one daughter cell will get the plasmid.
NOTE: Why do we not use the phrase Bacterial Chromosome? Many people use it, including microbiologists. It is an easy phrase, and immediately brings up to your mind the idea of the main genetic units of a cell, but what is a chromosome? A chromosome, by definition, is made of chromatin. These are the individual molecules of supercoiled DNA that appear only during Mitosis. Bacteria do not produce chromatin, and they do not undergo mitosis. Thus, they do not have a true chromosome. The term genophore, coined by Hans Ris, is thought of as a gene holding unit, or a unit of genetic linkages, i.e., a molecule of DNA. So, we should discuss the Bacterial Genophore, not the bacterial chromosome.
Daily Challenge: Bacterial Replication
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