20 MENIT PAHAM RESPIRASI SELULER [GLIKOLISIS SAMPAI TRANSPOR ELEKTRON]

Summary

This video provides an in-depth explanation of cellular respiration, breaking it down into four key stages: glycolysis, oxidative decarboxylation, the Krebs cycle, and electron transport. The process begins with the breakdown of glucose into two pyruvate molecules during glycolysis, producing ATP and NADH. The video further explores how these molecules are processed in the mitochondria, where they are converted into ATP through various reactions, particularly in the electron transport chain. The explanation also contrasts aerobic respiration with fermentation, demonstrating the importance of oxygen for maximizing energy production. The final takeaway is the total yield of 38 ATP from cellular respiration.

Takeaways

• 😀 Glycolysis is the first stage of cellular respiration where glucose is broken down into 2 pyruvate molecules, generating 2 ATP and 2 NADH in the process.
• 😀 The second stage is oxidative decarboxylation, where the 2 pyruvate molecules are converted into 2 acetyl-CoA, releasing 2 CO2 and producing 2 NADH.
• 😀 The third stage, the Krebs cycle (Citric Acid Cycle), uses 2 acetyl-CoA to produce 2 ATP, 6 NADH, 2 FADH2, and 4 CO2 through various chemical reactions.
• 😀 The fourth stage, electron transport chain (ETC), occurs in the inner mitochondrial membrane, where NADH and FADH2 are used to generate ATP, transferring electrons to oxygen and creating water.
• 😀 NADH is converted into 3 ATP, and FADH2 is converted into 2 ATP during the electron transport chain.
• 😀 If oxygen is not available, pyruvate undergoes fermentation, resulting in the production of 2 lactic acid molecules and only 2 ATP.
• 😀 In the presence of oxygen, the cellular respiration process can generate up to 38 ATP (or sometimes 36 ATP, depending on certain conditions).
• 😀 Glycolysis and the Krebs cycle both generate ATP directly through substrate-level phosphorylation, but most ATP is produced via oxidative phosphorylation during the electron transport chain.
• 😀 NADH and FADH2 produced in earlier stages of respiration carry high-energy electrons that are used to drive ATP production in the electron transport chain.
• 😀 The overall process of cellular respiration involves the breakdown of glucose and other substrates, with the aim of producing energy in the form of ATP for cellular functions.

Q & A

What is the first step in cellular respiration and where does it occur?

The first step is glycolysis, which occurs in the cytoplasm. During glycolysis, one glucose molecule is broken down into two pyruvate molecules.

What are the products of glycolysis?

The products of glycolysis are two pyruvate molecules, two ATP molecules (net gain), and two NADH molecules.

What happens during oxidative decarboxylation?

During oxidative decarboxylation, the two pyruvate molecules produced from glycolysis are converted into two acetyl-CoA molecules. This process also releases two CO2 molecules and produces two NADH molecules.

Where does the oxidative decarboxylation process take place?

Oxidative decarboxylation occurs in the mitochondria, specifically in the matrix.

What is the role of acetyl-CoA in cellular respiration?

Acetyl-CoA enters the Krebs cycle, where it combines with oxaloacetate to form citric acid, and through a series of reactions, it helps produce energy-rich molecules like NADH, FADH2, and ATP.

What is the Krebs cycle, and what does it produce?

The Krebs cycle is the third step in cellular respiration that occurs in the mitochondria. It processes acetyl-CoA and produces two ATP molecules, six NADH molecules, two FADH2 molecules, and four CO2 molecules.

What happens to NADH and FADH2 after the Krebs cycle?

NADH and FADH2 carry high-energy electrons to the electron transport chain, where they are used to produce ATP.

How does the electron transport chain generate ATP?

In the electron transport chain, NADH and FADH2 donate electrons that pass through protein complexes in the inner mitochondrial membrane. This process creates a proton gradient that drives the production of ATP through oxidative phosphorylation.

What is the total amount of ATP produced through cellular respiration?

Cellular respiration can produce up to 38 ATP molecules in total, with 4 ATP coming from substrate-level phosphorylation (direct production from glycolysis and the Krebs cycle), and 34 ATP coming from oxidative phosphorylation (electron transport chain).

What happens when oxygen is not available during cellular respiration?

When oxygen is absent, pyruvate does not enter the mitochondria for the Krebs cycle and electron transport. Instead, it undergoes fermentation to produce lactic acid in animals, generating only 2 ATP molecules.