Cellular Respiration in Action!

Did a fun demonstration with The Crew today that nicely demonstrates cellular metabolism.  It is a pretty common lab in high schools (done a little more scientifically that the Crew could handle) and involves yeast metabolizing glucose and producing CO₂. Here are some pics from the scene…

The Actress looking ever so happy creating our sugar solution for the little fungi to feed on.

The Analyst pouring our sugar solution into our ubiquitous plastic water bottle.

The Actress pouring our little "beasties" into the sugar solution.

We had a lot of fun with the topic of yeast.  The Crew was completely fascinated that we were going to buy something “alive” in a package at the grocery store and asked over and over again if they could open it, what did they look like, etc.  Needless to say they were a little disappointed little critters didn’t come jumping out of the package when we opened it, but that went away as we continued on with our little demo.

S. cerevisiae

For a bit of background on yeast…Yeast is one of the most useful and most carefully studied eukaryotic organisms in nature.  In fact, the same species of yeast sold in the grocery store (Saccharomyces cerevisiae) was the first fully sequenced eukaryotic genome in 1996.  They belong to the kingdom Fungi (along with molds and mushrooms) and have a huge number of uses from baking to alcohol fermentation in beer making and even some potential applications in bioremediation of hazardous chemical spills.  For more about yeast.

The Crew putting the balloon on top of the bottle to capture any escaping gas.

Presto! After 20 minutes or so our balloon starts to inflate. But with what??

After about 40 minutes, our balloon is almost fully inflated. The Crew was impressed!

The Science Behind It…

So what is that mystery gas in the balloon anyway?  Why is is CO2 of course!  That ever famous byproduct of cellular respiration.  You remember, the old dreaded…

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy (as ATP)

or…Glucose + Oxygen –> Carbon Dioxide + Water + ATP (the energy currency of cells)

or…Glycolysis –> Pyruvate Decarboxylation –> Kreb’s Cycle –> Electron Transport Chain

or…

Kreb's Cycle after completion of Glycolysis

Now did I go into any of this with the Crew?  No, we were content with “cool – look – the little creatures eat and breath and what they breath out blew up the balloon” – maybe we will do the aerobic and anaerobic biochemical pathways next week!

What is nice though is being able to see these reactions occur in the real world.  It makes it all a lot less abstract.