Cells make energy from food mainly through two main processes: cellular respiration and fermentation. Both of these processes break down organic molecules, like glucose, to produce ATP (adenosine triphosphate). ATP is the energy that cells use to work properly.
Glycolysis: This first step happens in a part of the cell called the cytoplasm. Here, one glucose molecule (C₆H₁₂O₆) gets broken down into two smaller molecules called pyruvate (C₃H₄O₃). During this step, the cell makes a little bit of ATP and some NADH. NADH helps carry energy to the next steps. From glycolysis, cells get a net gain of 2 ATP molecules.
Krebs Cycle: After glycolysis, the pyruvate moves into the mitochondria, which is known as the powerhouse of the cell. Here, it gets turned into something called Acetyl-CoA. This starts the Krebs Cycle. In this cycle, more energy carriers like NADH and FADH₂ are made, and carbon dioxide (CO₂) is released as waste. For every Acetyl-CoA used, the cell makes 1 ATP, 3 NADH, and 1 FADH₂.
Electron Transport Chain (ETC): The NADH and FADH₂ made earlier now go to the inner part of the mitochondria to the ETC. As electrons move through this chain, they release energy, which helps pump protons (H⁺) across the membrane. This creates a sort of battery. When the protons flow back through a special protein called ATP synthase, ATP gets made. This process can make up to 34 ATP molecules from one glucose molecule.
When there isn't enough oxygen, cells can still make energy by undergoing fermentation. For example, in our muscles, pyruvate gets turned into lactic acid. In yeast, pyruvate turns into ethanol and carbon dioxide (CO₂). Even though fermentation is less effective — only making 2 ATP per glucose — it helps keep energy production going when there's no oxygen around.
In summary, cells use processes like glycolysis, the Krebs cycle, and the electron transport chain to turn food into ATP. This way, they ensure they have enough energy for all their various activities.
Cells make energy from food mainly through two main processes: cellular respiration and fermentation. Both of these processes break down organic molecules, like glucose, to produce ATP (adenosine triphosphate). ATP is the energy that cells use to work properly.
Glycolysis: This first step happens in a part of the cell called the cytoplasm. Here, one glucose molecule (C₆H₁₂O₆) gets broken down into two smaller molecules called pyruvate (C₃H₄O₃). During this step, the cell makes a little bit of ATP and some NADH. NADH helps carry energy to the next steps. From glycolysis, cells get a net gain of 2 ATP molecules.
Krebs Cycle: After glycolysis, the pyruvate moves into the mitochondria, which is known as the powerhouse of the cell. Here, it gets turned into something called Acetyl-CoA. This starts the Krebs Cycle. In this cycle, more energy carriers like NADH and FADH₂ are made, and carbon dioxide (CO₂) is released as waste. For every Acetyl-CoA used, the cell makes 1 ATP, 3 NADH, and 1 FADH₂.
Electron Transport Chain (ETC): The NADH and FADH₂ made earlier now go to the inner part of the mitochondria to the ETC. As electrons move through this chain, they release energy, which helps pump protons (H⁺) across the membrane. This creates a sort of battery. When the protons flow back through a special protein called ATP synthase, ATP gets made. This process can make up to 34 ATP molecules from one glucose molecule.
When there isn't enough oxygen, cells can still make energy by undergoing fermentation. For example, in our muscles, pyruvate gets turned into lactic acid. In yeast, pyruvate turns into ethanol and carbon dioxide (CO₂). Even though fermentation is less effective — only making 2 ATP per glucose — it helps keep energy production going when there's no oxygen around.
In summary, cells use processes like glycolysis, the Krebs cycle, and the electron transport chain to turn food into ATP. This way, they ensure they have enough energy for all their various activities.