36. Biochemistry: Metabolism and Cellular Respiration

Chapter 36 of our Biology course for ENEM will address a crucial topic in Biochemistry: Metabolism and Cellular Respiration. It is an area that requires attention as it is frequently covered on the exam. Let's start by deepening our understanding of what metabolism is.

Metabolism

Metabolism is the set of chemical reactions that occur within cells to maintain life. It can be divided into two main parts: anabolism and catabolism. Anabolism is the building phase where simple molecules are converted into complex molecules. On the other hand, catabolism is the degradation phase, where complex molecules are broken down into simple molecules, releasing energy in the process.

Cellular Respiration

Cellular respiration is a catabolic process that occurs in cells to produce energy. It is a complex process involving several steps, including glycolysis, the citric acid cycle (also known as the Krebs cycle) and the electron transport chain.

Glycolysis

Glycolysis is the first step of cellular respiration and takes place in the cytoplasm of the cell. During glycolysis, one glucose molecule is broken down into two pyruvate molecules. This process produces a small amount of energy in the form of ATP (adenosine triphosphate) and NADH (nicotinamide adenine dinucleotide).

Citric Acid Cycle (Krebs Cycle)

The citric acid cycle occurs in the mitochondria and is the second step of cellular respiration. Here, the pyruvate produced in glycolysis is converted to acetyl CoA, which is then used in the citric acid cycle to produce NADH and FADH2 (flavin adenine dinucleotide), as well as a small amount of ATP.

Electron Transport Chain

The electron transport chain is the last step of cellular respiration and takes place in the inner membrane of the mitochondria. Here, electrons from NADH and FADH2 are transferred through a series of proteins, releasing energy that is used to make ATP. Oxygen is essential in this step as it acts as a final electron acceptor.

In summary, cellular respiration is a vital process that allows cells to produce energy from glucose. This process involves several steps and a series of molecules, each playing a crucial role in energy production. It is important to understand this process, as it is fundamental to life and is often a topic covered in ENEM.

We hope that this chapter has provided a clear overview of metabolism and cellular respiration. In the next chapter, we'll explore another important topic in biochemistry: photosynthesis. Stay tuned!

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