Sporulation

Endospore formation is a complex, highly ordered sequence of changes that initiates when cells are grown in low amounts of carbon or nitrogen (figure 3.47). Apparently the bacteria sense that they are facing starvation conditions and therefore begin the 8-hour process that prepares them for rough times ahead.

After vegetative growth stops, DNA is duplicated and then a septum forms between the two chromosomes, dividing the cell

Vegetative growth stops; DNA is duplicated.

Vegetative growth stops; DNA is duplicated.

A septum forms, dividing the cell asymmetrically.

The larger compartment then engulfs the smaller compartment, forming a forespore within a mother cell.

Peptidoglycan-containing material is laid down between the two membranes that now surround the forespore.

The mother cell is degraded and the endospore released.

Core wall

Cortex Spore coat

Figure 3.47 The Process of Sporulation

A septum forms, dividing the cell asymmetrically.

The larger compartment then engulfs the smaller compartment, forming a forespore within a mother cell.

Peptidoglycan-containing material is laid down between the two membranes that now surround the forespore.

Core wall

The mother cell is degraded and the endospore released.

Cortex Spore coat

Figure 3.47 The Process of Sporulation asymmetrically. The larger compartment then engulfs the smaller compartment, forming a forespore within a mother cell. These two portions take on different roles in synthesizing the components that will make up the endospore. The forespore, which is enclosed by two membranes, will ultimately become the core of the endospore. Peptidoglycan-containing material is laid down between these two membranes, forming the core wall and the cortex. Meanwhile, the mother cell makes proteins that will form the spore coat. Ultimately, the mother cell is degraded and the endospore released.

The layers of the completed endospore function together, protecting the structure from damage. The spore coat is thought to function as a sieve, excluding molecules such as lysozyme. The cortex helps maintain the core in a dehydrated state, which protects it from the effects of heat. In addition, the core has small, acid-soluble proteins that bind to DNA, altering its conformation and protecting it from damage. The core is rich in an unusual compound called dipicolinic acid, which combines with calcium ions. This complex appears to also play an important role in spore resistance.

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Bacterial Vaginosis Facts

Bacterial Vaginosis Facts

This fact sheet is designed to provide you with information on Bacterial Vaginosis. Bacterial vaginosis is an abnormal vaginal condition that is characterized by vaginal discharge and results from an overgrowth of atypical bacteria in the vagina.

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