Stain: Parasite to Yeast Cells?

A couple days ago, I conducted another experiment where I put yeast cells in dye to see what would happen when yeast cells were put in beakers with stain in either normal conditions or boiled conditions. Along with this, there was a beaker with yeast cells in no dye and normal temperature conditions. After a couple hours, I checked back on the yeast cells. Let's take a look at the results and the explanation behind them.

https://www.google.com/search?sca_esv=9766d7d73f8895cf&rlz=1C5OZZY_enUS1127US1127&sxsrf=ADLYWIIUTcoY_qv-CDUBxVTI0NiXX9HjSg:1733357547480&q=yeast+cells&udm=2&fbs=AEQNm0Aa4sjWe7Rqy32pFwRj0UkWd8nbOJfsBGGB5IQQO6L3J03RPjGV0MznOJ6Likin94pT_oR1DTSof42bOBxoTNxGeB1pS5_mub79WlyOO98XhEgJ5ByfFkeFUd9hlGBCmUZgrzLESyrkqGBL7osK5ZH3-0drzcH2VIMmwLRButbs-cMHhV8leQ--AYHsqw2WSrddKuHyCX6iowNOKZDTcJOO0G_14g&sa=X&sqi=2&ved=2ahUKEwjWm4uHrI-KAxXKFmIAHdqpAc8QtKgLegQIFBAB&biw=1710&bih=981&dpr=2#vhid=oQHFzA-2u0DROM&vssid=mosaic:~:text=Yeast%20Cells%20at%20Work%20%7C%20News%20%26%20Events%20%7C%20University%20of%20Miami

What are Yeast Cells?

Yeast cells are known to be single-celled microorganisms that are classified as fungi. They have a nuclear membrane in their cell, which means they also have a true nucleus, making them eukaryotic cells. Eukaryotic cells are cells that contain a defined nucleus and organelles within their cellular structure. Yeast cells are found various environments, such as soil, plants, water, and even inside animals, including humans. The three main things a yeast cell should contain is a nucleus, cell wall, and a cytoplasm.

Results

In the beaker with no stain or boiled temperatures, the yeast cells remained normal.

Yeast cells in normal temperature

In the beaker with stain and room temperature levels, the yeast cells remained unstained, except for two yeast cells.

Only two yeast cells are stained with the stain in this picture

https://www.google.com/search?q=two+yeast+cells+colored+blue&sca_esv=9766d7d73f8895cf&rlz=1C5OZZY_enUS1127US1127&udm=2&biw=1710&bih=981&sxsrf=ADLYWIKh04ARko9ncXGZ6q9yRIEX21t_YA%3A1733359167593&ei=P_ZQZ5ftI7ag5NoPkqzx8AU&ved=0ahUKEwjXiM-Lso-KAxU2EFkFHRJWHF4Q4dUDCBA&uact=5&oq=two+yeast+cells+colored+blue&gs_lp=EgNpbWciHHR3byB5ZWFzdCBjZWxscyBjb2xvcmVkIGJsdWVIrDxQsgNYxTtwCHgAkAEAmAGIAaABmA2qAQQyOS4yuAEDyAEA-AEBmAIMoAKtBagCCsICBxAjGCcY6gLCAgQQIxgnwgIKEAAYgAQYQxiKBcICCxAAGIAEGLEDGIMBwgIFEAAYgATCAggQABiABBixA8ICBBAAGB7CAgYQABgIGB6YAwuSBwQxMS4xoAfjRg&sclient=img#vhid=dJGYmBPbq9NVAM&vssid=mosaic:~:text=Search%20inside%20image-,Microscopy%20of%20Yeast%20used%20in%20the%20Fermentation%20of%20Beer%20and%20Wine%20%7C%20Motic%20Microscopes,-Visit

In the third beaker where the water temperature was boiled, all the yeast cells were stained.

All yeast cells are stained with the dye

https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.istockphoto.com%2Fphotos%2Fmethylene-blue-stain&psig=AOvVaw0ymE5fGZJ_Siq7r2UIIdn- &ust=1733446413405000&source=images&cd=vfe&opi=89978449&ved=0CBcQjhxqFwoTCOj13se4j4oDFQAAAAAdAAAAABAE

The Reason Why?

Yeast cells all have a selectively permeable membrane, which means only a few things can go in and out of the cell. In the second beaker, the yeast cells all remained the same because none of the dye was able to enter the cell due to active transport mechanisms. Active transport mechanisms are ways to transport large molecules into and out of the cell through a process called endocytosis. The stain couldn't enter the cell because protein pumps, a active transport mechanism, were constantly pushing the stain out of the cell. The protein pumps use energy (ATP) to push the stain out of the cell, even though they are a fairly small substance that could easily diffuse between the phospholipid bilayer, which makes up the cell membrane. As you probably noticed, two of the yeast cells were still stained in the second beaker. This is because those two cells must have been damaged prior to the experiment, which is why the stain was able to diffuse through the cell membrane and stain the cell. Since the cell was damaged, there were no working active transport mechanisms that could pump out the stain and the cell membrane did not work efficiently enough to keep its selective permeability.

In the first beaker, everything remained the same because there was no stain or dye to enter the cell membrane of the yeast cells.

In the third beaker, the water was boiled and all the yeast cells were stained. Boiling temperatures denature the yeast cells. Denaturation is a process of when a cell or enzyme loses its shape and function when it is put in a boiling temperature. Because of this, the yeast cells lost their functions, which also made them lose their active transport mechanisms. Along with the shape of the cells, the cell membrane lost its selective permeability, and the active transport mechanisms no longer functioned because they were damaged. Therefore, all the yeast cells were stained.

Due to this experiment, we can conclude that active transport mechanisms were the main reason the cell was able to keep the stain out of the cell, even though the substance was small, non-polar, uncharged, and could've easily slipped through the phospholipid bilayer. Additionally, the beaker with boiled water had stained yeast cells because those cells were denatured and lost their functionality and shape. Because of this, stain slipped through the no longer selective permeable cell membrane and was able to stain the cell since there were no more active transport mechanisms that would pump out the toxic substance.

Stay tuned for more experiments like this!

Darvika Sharma