Ch. 18 - Bacteria

Today in class we discussed the genetics of bacteria.

-Conjugation is a means of genetic variation in bacteria. A bacteria with the presence of the F factor in their genes will produce a pili. The pili will allow the two bacteria to get close enough to each other so that a conjugation bridge may form. The conjugation bridge not the pili is where the genetic material of the bacteria is exchanged.

4 modes of nutrition for bacteria

-photoautotroph: photosynthetic organisms that capture light and use it to drive synthesis of organic compounds.

-chemoheterotroph: consume organic molecules to obtain energy and carbon.

-chemoautotroph: need an inorganic compound such as carbon dioxide as a carbon source.

-photoheterotroph: harness energy from light but must obtain carbon in organic form.

-bacteria is an essential decomposer in the world.

Genetics

-bacteria have the ability to control gene expression, allowing them to adjust their metabolism to environmental change. Cells control metabolism by regulating enzyme activity or by regulating enzyme synthesis through activating or inactivating genes

-bacteria cell that can conserve resources and energy have a selectable advantage over cells that are unable to do so. Thus, natural selection has favored bacteria that express only the genes whose products are needed by the cell.

-An operator is a segment of DNA that acts like a switch to either turn on or off a gene. Basically the operator is the access point to the RNA polymerase. If the polymerase can get to the gene to code it, it will be expressed.

LAC Operon

-Inducible operon, it is usually off and can be induced/stimulated when a specific small molecule interacts with a regulatory protein.

-Alla lactose, an isomer of lactose, derepresses the operon by inactivating the repressor. In this the enzymes for lactose utilization are induced.

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