What the Krebs

Posted by Worldview Warriors On Thursday, December 18, 2014 0 comments

by Steve Risner

This week I wanted to touch on a process that is basic to every form of life we are aware of on earth—the Krebs' Cycle, or Citric Acid Cycle. At first, I wanted to outline it in detail and talk about its complexities and the silliness of the thought that it arose by chance. However, I quickly realized that such a blog would not be read by anyone because it would be similar to reading a higher-level science text - a.k.a. boring. So I've decided to just write a bit on energy and how life—all life—depends on it.

The Krebs' Cycle, named after Hans Krebs, an American biochemist, who discovered it in 1937, is what turns glucose (the most common form of sugar in our bodies) into useful energy. There are 8 basic steps to this process, and it's quite amazing to think of the detail in creating something so basic to our existence—energy.

Why do we need energy? Of course, without energy we could do no work—chemical, electrical, or mechanical work all requires the expenditure of energy. We house energy in a chemical called ATP—adenosine triphosphate. ATP is made in the Krebs' Cycle. There are other processes involved before and after the Krebs' Cycle that use ATP, so the argument quickly becomes a chicken/egg discussion if you believe in evolution from a single common ancestor. It's just nonsensical. So let's look at different ways we make energy.

We eat food. It's yummy. It tastes good and we enjoy it. I suppose that's motivation our Creator gave us to sustain us. We need food not for a good time at dinner but to generate energy and acquire nutrients to perform the complex processes we are always involved in that keep us alive. Food is digested in a series of stages from chewing and saliva through the stomach and all the way to the end of the GI tract and back out to the outside world. Along this pathway, nutrients are snatched from our food. Glucose, a sugar, is a basic nutrient that eventually starts our story, so let's talk about it for a moment.

Sugar is what we break up into little energy packets. We do this all day, every day, as long as we are living. Every cell of the body requires energy to do whatever it is that it does. Glucose is broken down into smaller molecules, which eventually become acetyl CoA. This compound is what undergoes changes in the Krebs' Cycle to release energy molecules. This pathway is called glycolysis, which simply means “breaking sugar.” But we are so marvelously built that we can actually make glucose out of other things—namely fat and protein! That's amazing. In fact, you don't need to eat ANY glucose in order to live because your body can make it out of other things. I often tell my chiropractic practice members struggling with their diet that there is no such thing as an essential carbohydrate. If you don't eat them, you make them. How cool is that?

So proteins are broken down into amino acids, which can be converted into acetyl CoA, which enters the Krebs' cycle and BAM! Energy is produced. Triglycerides (fat) can be broken down into fatty acids and glycerol. Glycerol is converted into... you guessed it.. glucose, which is turned into acetyl CoA and BOOM! Energy is produced. Our Maker knew what He was doing.

Think of this: each cell in your body, on average, will consume (after generating) about 10 million molecules of ATP every second! What?! I could show you all the math that comes up with this completely theoretical number, but let's just assume it's pretty close. That's jaw dropping, isn't it, when we consider there are approximately 100 trillion cells in our bodies (depending on who you talk to). Looking for calculations on the Internet (which I admit is sketchy), it looks like the average human uses about 100-150 Watts of power in a day, or the energy an average light bulb would consume. Is that startling to anyone else? Most of the appliances in your home consume far more energy than you do. Again, our Creator is astounding!

Then there are organisms that simply sit in the sun and generate energy! How nice would it be if you could just sit outside for a few minutes and generate the energy you needed to get through the day? Plants (and several other organisms) have the ability to turn light energy into usable energy to sustain themselves—a process called photosynthesis. It just so happens that they use our waste products to make energy and survive, and we use their waste products to make energy and survive. What an awesome cycle!

I pray in reading this you're not overwhelmed with jargon or technical stuff. I did my best to reduce the boring stuff most of us would gloss over. In essence, the bottom line is the Krebs' Cycle is astoundingly complex and important. ATP, the primary (although not the only) product of the Krebs' Cycle is what every known living thing uses for energy. We make ATP from glucose—a sugar. We can eat sugar or make it from proteins or fat. There are hundreds of enzymes that move different products down multiple paths to go from hamburger and milkshake to usable energy. You are, literally, what you eat.

Brian Thomas of creation.com says this concerning ATPase (an enzyme used to break ATP and extract its energy): “Since evolution by natural selection requires reproduction, and since reproduction requires life, which requires ATPase, the enzyme is therefore a prerequisite for evolution. But with evolution out of order until ATPase ‘appears’, evolution is not even in the running as a model to explain the origin of the molecular motor.”

Let's reflect on the fact that God is the Creator and Sustainer of life.
Colossians 1:17, “He is before all things, and in him all things hold together.”
1 Corinthians 8:6, “Yet for us there is one God, the Father, from whom are all things and for whom we exist, and one Lord, Jesus Christ, through whom are all things and through whom we exist.”