In this video, we're going to begin our lesson on endospores. Recall from way back in our previous lesson videos that a scientist named John Tyndall discovered a heat-resistant form of bacterial cells, which were later termed endospores. These endospores can be defined as a dormant cell that is only produced by some bacteria and are highly resistant to damaging conditions. Because these endospores are resistant to damaging conditions, this means that they're able to survive in conditions where most normal cells would not be able to survive. And because these endospores are dormant, what that means is that they have lowered activity and they are not going to be able to perform the same functions as normal cells would.
Once again, they are highly resistant to damaging conditions such as extreme amounts of heat, toxic chemicals, and nutrient depletion. These endospores are able to survive a lot of conditions where most normal cells would not be able to survive. It's also important to note that endospores are not a form of replication, and so it does not allow a cell to replicate and reproduce. Instead, endospore formation is going to start and end with a single cell, and it does not form more cells, so it's not a form of replication.
Instead, endospore formation is a form of survival. It allows cells to survive these damaging conditions where they might not otherwise be able to survive. A vegetative cell is the scientific way to refer to a normal cell that is going to be replicating and is not dormant. We'll be able to see how vegetative cells can actually form endospores when nutrients are depleted down below in this image. Notice on the left-hand side over here, what we're showing you is a vegetative cell, the normal bacterial cell under normal conditions.
There are nutrients available in the environment, represented by hexagons that indicate glucose. However, when there are no nutrients available, the vegetative cell can undergo a process called sporulation, which we'll talk more about later. This process forms an endospore. When nutrients are depleted, the cell can begin to form an endospore. The endospore is still alive. However, it is a dormant cell and is going to have lowered activity and is not going to be able to perform the same functions as the vegetative cell.
It is able to survive the conditions when there's no nutrients. Once nutrients become available again, the endospore can undergo a process called germination, which we will talk more about later in our course as well. This process by which an endospore reverts back into a vegetative cell. Endospores are usually only produced by gram-positive cells, such as Bacillus and Clostridium, two examples of bacteria that are gram-positive and produce endospores.
One way to help you remember that it's gram-positive cells that typically form endospores is that you could think of endospores as dormant like winter clothes in the summer at the back of your closet. What you can think is when the temperature is positive Celsius, so when the temperature is warm like in the summer, your winter clothes are going to be in a dormant state in the back, and you're not going to be using them very often. By thinking of the positive Celsius here, that can help remind you of gram-positive cells that form endospores. This here concludes our brief introduction to endospores, and we'll be able to apply the concepts that we've learned here as we move forward.
So I'll see you all in our next video.