Wednesday, January 3, 2024

Exeter-Milligan Update: Science


Little Cell, Little Cell, Let Me Come In!

By Matt Nicholas, Exeter-Milligan Science Instructor


All living things are made of cells that are too small to see without a microscope. They are very complex collections of DNA, organelles, and a soup of nutrients called cytoplasm, but all of those parts are held inside the cell by the cell membrane. This membrane is the exterior of the cell, but it is also the bouncer or gate keeper. How then do gases, nutrients, hormones, and other chemicals get into and out of our cells? Well, it turns out that there are many ways to get into a cell depending on what is knocking at the door.


The EM Biology class has been hard at work studying all methods of membrane transport from Passive(zero energy) methods like diffusion and osmosis, to Active(non-zero energy) methods like the Sodium-Potassium pump. On Monday however, the class had to do a bit of acting. They got to be their best phospholipids and act out endocytosis and exocytosis. Too keep it short, endocytosis is when substances enter the cell by caving in and pinching off a “bubble” of the membrane around the substance, and exocytosis is when a “bubble” from inside the cell joins with the membrane and empties its contents into the surroundings.

As seen in the picture, several students are linked together to make the plasma membrane, and Selah Petersen is the substance trying to get into the cell(top left). The students making up the membrane cave in to make space for Selah(top right), she enters the space(bottom left), and then the students close in on themselves making a vesicle, the bubble from earlier, around her(bottom right). She is now inside the cell and free to do whatever function is needed. This is the endocytosis process. If run in reverse, it would be exocytosis.


As these processes play out on scales smaller than the hair on my chinny chin-chin, it can be hard to comprehend, but don’t huff and puff! If you are looking for an expert on the “in’s and out’s” of cells, just ask one of your favorite EM Biology students!


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