GLICÓLISE | Biologia para o Enem | Cláudia de Souza Aguiar

Summary

This video explains glycolysis, the breakdown of glucose during cellular respiration. The process occurs in the cytosol of both prokaryotic and eukaryotic cells, and it doesn’t require oxygen. Glycolysis involves the conversion of glucose into two molecules of pyruvic acid, producing energy in the form of ATP and NADH. Despite an initial energy investment, the process generates a net gain of two ATPs. For eukaryotic cells, the energy produced is used in the subsequent Krebs cycle. The video also touches on the role of enzymes, particularly phosphokinase, in accelerating the reaction, and highlights the significance of glycolysis in cellular energy production.

Takeaways

• 😀 Glycolysis is the breakdown of glucose, a key part of cellular respiration, occurring in both prokaryotic and eukaryotic cells.
• 😀 The process takes place in the cytosol (liquid part of the cytoplasm) and does not require oxygen, making it anaerobic.
• 😀 Glycolysis is catalyzed by enzymes, with phosphokinase being the most crucial in speeding up the reactions.
• 😀 The process begins with the expenditure of ATP to convert glucose into glucose-6-phosphate, which then undergoes further modifications.
• 😀 Glucose-6-phosphate is isomerized into fructose-6-phosphate, followed by another ATP expenditure to form fructose-1,6-bisphosphate.
• 😀 Fructose-1,6-bisphosphate splits into two three-carbon molecules, leading to the formation of molecules like glyceraldehyde-3-phosphate (G3P).
• 😀 ATP is generated during the conversion of 3-phosphoglycerate to 2-phosphoglycerate, which then becomes phosphoenolpyruvate (PEP).
• 😀 The final step of glycolysis involves the production of pyruvic acid, with ATP generated by the transfer of phosphate to ADP.
• 😀 The net gain of glycolysis is 2 ATP molecules, 2 NADH molecules, and 2 pyruvic acid molecules, though 4 ATPs are produced in total during the process.
• 😀 Although 4 ATP molecules are produced, the net gain is 2 ATP because 2 ATP molecules are used in the early steps of the process.
• 😀 For eukaryotic cells, the pyruvic acid and NADH produced will enter the Krebs cycle for further energy production, while prokaryotic cells can directly use the generated energy.

Q & A

What is glycolysis?

Glycolysis is the process of breaking down glucose into smaller molecules to produce energy, specifically ATP. It occurs in the cytoplasm of both prokaryotic and eukaryotic cells and does not require oxygen.

Where does glycolysis take place in the cell?

Glycolysis takes place in the cytosol, which is the liquid part of the cytoplasm, in both prokaryotic and eukaryotic cells.

Is glycolysis an aerobic or anaerobic process?

Glycolysis is an anaerobic process, meaning it does not require oxygen to occur.

What role do enzymes play in glycolysis?

Enzymes catalyze the reactions of glycolysis, speeding up the breakdown of glucose and the production of energy molecules like ATP and NADH. One of the key enzymes is phosphokinase.

What is catabolism in the context of glycolysis?

Catabolism refers to the process of breaking down larger molecules into smaller ones to release energy. In glycolysis, catabolism helps accelerate the breakdown of glucose to produce energy.

Why is ATP used at the beginning of glycolysis?

ATP is used at the beginning of glycolysis to provide the necessary energy to modify glucose and prepare it for further breakdown into smaller molecules.

What molecules are produced at the end of glycolysis?

At the end of glycolysis, two molecules of ATP, two molecules of NADH, and two molecules of pyruvic acid are produced.

Why is there a net gain of only two ATP molecules in glycolysis?

Despite the total production of four ATP molecules during glycolysis, two ATPs are consumed at the beginning of the process, resulting in a net gain of only two ATPs.

What happens to pyruvic acid after glycolysis in eukaryotic cells?

In eukaryotic cells, the pyruvic acid produced during glycolysis is used in the Krebs cycle for further energy production.

How is NADH generated during glycolysis?

NADH is generated during glycolysis when glucose is broken down into smaller molecules. NAD+ accepts electrons during the process and is reduced to NADH, which can later be used for energy production in other processes like the Krebs cycle.