Cellular Respiration

Hey everyone. Hows the Bio learning coming? Well I hope.  I've been taking in bite sized chunks and really mulling over this concept the past few days- and I finally think I understand it enough to explain it. Which, if you think about it, is the best way to learn. After soaking up a concept, explaining it to other people in different terms allows you to check yourself to see if you really understand it. 

Think of it this way- if you're having trouble with a concept- listen to a bunch of different explanations (whether from teachers or videos or diagrams or books) and then try explaining it to a friend. You sort of end up reaching a higher level of understanding. 

Come to think of it... this is exactly why teachers are so darn educated in their field. It takes a seriously deep understanding to be able to teach other people a concept. 

So, all that jazz aside, we have Cellular Respiration. Prepare yourself- this concept is all about zooming in and zooming out. And all I mean by that is that we have a really complicated multi-step process, so to understand it, we go from each chunk, back to the "whole", back to a chunk, out to the whole, etc. That way we get how each piece fits- but we don't forget the "point" of it all. 

First things first then, what the heck is Cellular Respiration? Well, in essence, it's when we take food and turn it into energy. More specifically- it's when we bust apart a sugar for it's energy so we can slap a bunch of ATP's together and Voilà- you have a "useable" energy currency. 

I say currency because that's essentially what energy is. It's money- but it's got to be in the right form to be "cashed" in. You can't just go to Walmart with a bunch of Canadian money and expect to buy anything. (They'll just look at you funny). 

So how does our body turn that delicious blueberry muffin you ate for breakfast into cashable ATP (and hence into muscle contractions and/or movement) ??? 

Lets start with the organic molecule that makes up the muffin. Starch, and simple sugars. Maltase comes in and helps bust apart the long starch chains into disaccarides, and other enzymes in your stomach break those up into individual glucose molecules. 

So, we have a glucose molecule. Now what? 

There are FOUR stages to harvesting this energy: Glycolosis, The Krebs Cycle (or Citric Acid Cycle), the Electron Transport Chain, and ATP synthesis. I'm going to provide a BREIF explanation of each, and then give you the video that I learned from. My advice is to watch the video, and then try and put the info in your OWN words. Make sense? Okay, here we go....

For each molecule of Glucose we should (best case scenario) get 38 ATPS. 

Glycolosis: 

In a nutshell- this is just where the Sugar gets broken up and turned into two molecules of Pyruvic Acid. There's an investment phase, where you "spend" two ATP's, and a "payoff" phase, where you get four ATP's back- for a net of two ATP's. 

Krebs Cycle: 

This is where each of those pyruvates turns into Acetyl CoA, then into Citric Acid, and back again. In the process a bunch of NADH's and FADH2's are made (you'll learn what those are if you watch the videos). 

ETC: 

The Coenzymes NADH and FADH2 are used to pump H+ across the membrane of the mitochondria- resulting in an electro chemical gradient (a charge across a membrane). An electron "falls" down this chain of enzymes- releasing energy (more NADH and FADH2). 

ATP SYNTHESIS: 

Finally, with the energy we've accumulated, a protein complex is turned like a peice of machinery, and ATP's are squished together. 



Now, I know my explanations are pretty sad compared to the videos- but thats the point. We go back and forth between detail and generalizations to show that a concept really makes sense. So, off you go. Below are the Khan videos, and an excellent "sum it all up" video from Crash Course (really funny science guy). 

Here you go.... 




INTRO TO CELLULAR RESPIRATION

GLYCOLOSIS: 

KREBS CYCLE: 

ETC: 

OXIDATIVE PHOSPHORALATION AND CHEMIOSMOSIS: 

Crash Course ATP Synthesis Video: 

NOTE: 
This video was actually in a previous post- BUT, now that you've picked up quite a few new vocab terms and morsels of info- you might want to take a second look. I did, and it was tremendously helpful. Besides, he's a funny guy...