Rucete ✏ Biology In a Nutshell
1. What is Phosphorylation?
Phosphorylation is the process of adding a phosphate group (Pi) to ADP to form ATP, which is essential for energy production in cells. There are two main types:
2. Substrate-Level Phosphorylation
- ATP is directly synthesized from a substrate molecule without passing through the electron transport chain.
- A phosphate group is transferred from a high-energy substrate to ADP, forming ATP.
- Occurs in:
- Glycolysis (Cytoplasm)
- Krebs Cycle (Mitochondrial Matrix)
3. Oxidative Phosphorylation
- ATP is produced through the electron transport chain (ETC).
- Electrons move through the ETC, releasing energy to pump protons (H⁺ ions) across the inner mitochondrial membrane.
- ATP Synthase uses the proton gradient to convert ADP into ATP.
- Occurs in:
- Inner mitochondrial membrane
4. In a nutshell - Differences Between the Two Types
| Type | Process | Energy Source | Location |
|---|---|---|---|
| Substrate-Level Phosphorylation | Direct transfer of a phosphate group from a substrate to ADP. | High-energy substrate molecule. | Cytoplasm (Glycolysis) & Mitochondrial Matrix (Krebs Cycle). |
| Oxidative Phosphorylation | Uses the electron transport chain (ETC) to generate ATP. | Electrons moving through the ETC. | Inner mitochondrial membrane. |
In a nutshell
Substrate Transfers, Oxidative Powers ATP!
- Substrate-Level Phosphorylation = Direct phosphate transfer → Quick ATP production.
- Oxidative Phosphorylation = ETC + ATP Synthase → High ATP yield.
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Biology in a nutshell