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ETD 31: A. Give the complete equation for cellular respiration. B. Explain how it is similar to combustion. C. Explain why you don't catch on fire.
December 02, 2013 at 4:03pm


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anne paige; Sam Paige
December 02, 2013 at 8:19pm


What I have learned from Sam is that number 1) the formula for cellular respiration is

C6H12O6 +6O2-----> 6CO2+6H2O+ATP+Heat. Next he taught me that cellular respiration and combustion reactions are similar in many ways, they both need to break bonds to release energy, they both have oxidation reactions, and they both need a small jumpstart called activation energy to start. Sam explained to me that it is like a car where before the engine can run it needs a spark of energy to start the consumption of gas. He taught me that the reason we don't catch on fire is because our body heat does not provide enough energy for the "activation energy". However he explained how the activation energy is like a hurdle and the glucose going through Cellular Respiration is like a hurdler; The hurdle is to high for the hurdler to jump at first, then the official (the enzyme) lowers the hurdle and the hurdler can make it. He used this analogy to show me how cellular respiration needs too much energy to start outside the body but once in the stomach the enzymes make it easier for the reaction to start.



So my mom does not do well in science so this one was very hard to do. It took many attempts and a lot of time to teach her about this topic. First I needed to teach her what CR was, then I needed to explain the formula. Next I had to teach her why it is similar to combustion reactions. At first I tried to talk about the role of electrons and made an analogy of it being like girls of different strengths fighting over a purse in a sale. This kind of worked and she understood the concept of some atoms  holding electrons better than others but it was still kind of fuzzy. Then I tried to teach her about why we don't catch on fire and I used the car analogy from today in class to teach her about activation energy and it worked great. The best part is that while teaching my mom, even though it took a long time to teach about part B I now understand the role of electrons so much better after taking so long reviewing my notes and such to teach my mom. Also I was able to think up a new analogy for activation energy to help my mom and it ended up helping me to. So while my mom is not the best at science in the long run even though my mom is harder to teach it helps me more.

Francisco Perez
December 02, 2013 at 8:36pm

Parent: Today Francisco told me all about cellular respiration and why it is essential to our everyday lives. Cellular Respiration involves glucose and oxygen to produce energy, water, and carbon dioxide. Also, he told me how Cellular respiration involves the breakdown of glucose such as combustion. However, unlike combustion we do not catch on fire because cellular respiration moves electrons in more controlled and slower steps.

Student: I told my mom about Cellular respiration and how it works. We need Cellular respiration to produce ATP which is necessary for various activity to happen. Also, i told my mom how combustion is similar to cellular respiration but both have different results. Unlike, cellular respiration, combustion leads to a start of fire because of the quick movement of the electron dropping levels. In cellular respiration, enzymes are used to gradually bring down the electrons from high to low. 

Sophie Wulfing
December 02, 2013 at 8:49pm

Tony- C6H12O6 (Glucose) + 6O2 => 6CO2 + 6H2O + Heat + ATP - where are the phosphates and stuff coming from?  Because electrons are distributed away from the carbon atoms, makes things to strip them, thus the glucose is a reducing agent.  Reducing implies gives up electrons.  Same for O2, electrons are distant from the Ox nuclei, makes it an oxidizer.  In water electrons are closer to their nuclei.  Same with CO2.  So reaction goes from high P.E to low, makes heat.  Combustion is the same equation:  Fuel + ox => smoke and energy (heat).  The reason why we don't spontaneously combust is combustion releases light energy which makes electrons jump quickly in their shells.  If we did this we'd catch on fire, but enzymes help us release energy in steps, releasing heat instead of light.

Sophie- I learned why the equation goes from high to low energy, which is related to how easy it is to strip electrons from a molecule. NADH provides the reaction with one proton and two electrons each time it is used. This shows how mitochondria is like a hydro electric dam in that it takes energy from the moving water step by step

Allie Duven
December 08, 2013 at 5:51pm

Parent: At first I thought that cellular respiration was related to the way cells breathe. After talking with Allie, I learned that it is the process of breaking down molecules to extract energy from the bonds that can be used to fuel cellular activity. Cellular respiration is similar to combustion because both reactions rely on fuel (reducing and oxidizing agents) to start the reaction; the difference is that in cellular respiration, enzymes are used during the reaction. Both result in smoke (CO2 and H20) and energy. It is the job of the enzymes to slowly release the electrons and prevent us from catching on fire each time cellular respiration takes place.

Allie: I enjoyed teaching my Dad about cellular respiration because he initially assumed that it was related to cells breathing which was what I originally thought the first time I learned about cellular respiration. I helped to show the difference between cellular respiration and combustion by comparing and contrasting them, showing how both reactions need fuel and result in smoke and different types of energy but that enzymes are an important component in cellular respiration. The enzymes are present to slow down the release and transfer of electrons to prevent us from catching on fire. I used the analogy of stairs versus a slide. Combustion is like a slide because the electrons transfer quickly and there is nothing to slow them down. Cellular respiration would be like stairs because the transfer of electrons happens more slowly due to the presence of enzymes.

Kevin Turek
January 01, 2014 at 11:16am

Parent: Kevin told me that combustion and cellular respiration are similar because they both become oxidized meaning that they break bonds to release energy.                                                              C6H12O6 +6O2-----> 6CO2+6H2O+ATP+Heat. Then he explained that we don't catch on fire from this because we take this process in steps rather then all at once.

Student: I told my mom the reaction for cellular respiration. Then I told her that this very similar to combustion as they both break bonds and release energy. But that this is done slowly so that way we do not burn up like the marshmallow because this process is down in slow steps.


Kelli Vetter
January 04, 2014 at 8:00pm

Parent: I learned that cellular respiration and combustion are similar in the way that both use some type of fuel and oxygen to create smoke (CO2) and heat. In the case of cellular respiration, it creates both heat and ATP which can be used for movement in the body. Our enzymes help control the steps of cellular respiration so that we don't catch on fire.

Student: I found it difficult to discuss this with my mom because I wanted to talk about the different steps of cellular respiration like glycolysis, Kreb's and oxidative phosphorylation  but I wanted her to understand what I was saying. I described the difference in combustion and cellular respiration in that combustion creates heat and fire quickly because the electrons are not being controlled unlike cellular respiration which uses enzymes to slow the electron movement. Enzymes release heat energy in each step precisely and slowly so that we do not catch on fire.  

Madison Boggan
December 02, 2014 at 5:36pm

Parent: I learned that when you breathe in oxygen you use enzymes to break down food (glucose) into energy and you exhale CO2. Cellular respiration is like combustion because whether it is a log or the food we intake, it has a high energy until it is broken down. We don't catch on fire because we break things down in steps using enzymes. Also, do we not catch on fire because we are mostly made of water?? 

Student: I simplified the process of cellular respiration very much to get to the main idea that it turns food into energy. I also explained the formula and made it relatable by explaining to her how it connects to breathing. In regards to it being similar and different than combustion, we mutually came up with the idea that our bodies break things down by using stairs but combustion breaks things down by sliding down the stairs without using steps. I was happy that my mom helped come up with this. She remains convinced that we don't catch on fire because of the water inside us rather than using enzymes to process food in steps. I tried.

Lauren Masters
January 02, 2016 at 7:08pm

Parent: Lauren taught me that cellular respiration and combustion are similar in that they both release energy but that cellular respiration is done is steps, like going down stairs (slower process) and combustion is like going down a slide (faster process). Both create energy (ATP). Formula is C6H12O6+6O2 (CHO/Glucose)---->6CO2(carbon dioxide)+6H2O(water)+energy. Electrons travel between different rings of a circle; moving towards the center as they lose energy and moving towards the outer level (valence shell) as they gain energy,

Student: I shared how cellular respiration and combustion are different. I had to simplify it down by saying that combustion is like a slide that goes fast and that cellular respiration is like stairs because it has many steps to it. I also told her the similarities such as that they both release energy. I also tried to explain to her how electrons move between shells due to their energy levels. Electrons gaining energy move outward and electrons losing energy move inward.

Amber Neathery, Period 3
January 03, 2016 at 10:45pm

Student: I told my dad that burning wood to generate heat energy is similar to breaking down food in our bodies to release ATP as energy- both are catabolic reactions. Glucose and oxygen, which have high potential energy because of their chemical bonds, are converted into carbon dioxide, water, and ATP, which have low potential energy. I told him that cellular respiration is a redox reaction (meaning that electrons are transferred between molecules) and that it is also an exothermic reaction (energy is released in the form of ATP). Therefore, the delta G value (change in free energy) is negative. Even though cellular respiration and combustion are similar, humans don't catch on fire upon digestion because enzymes regulate these processes and break them down into steps. 

Parent: amber said that our bodies burn food to give energy. this is exothermic because delta G is negative. hard to comprehend what delta G is but she later said it is change in energy. it is not completely like burning firewood because of enzymes.  

Katarina Zosel
December 14, 2017 at 10:13pm

Older Sister: 

Part Aye: C6H12O6 plus 6O2 = 6CO2 + ^HtwoO plus enerGy

Section Bee: You're burning bridges and breaking bonds (James bonds) 

Sea: Because we don't want to explode, we like being slinky's 

Student: My sister already had an idea of what cellular respiration was, so explaining the equation was not very difficult. However, for combustion, I had to explain more on a molecular level how individual bonds lower the energy levels of the electrons slowly in cellular respiration, like a slinky going steps one at a time, however combustion is just a rapid break off all bonds.

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