MCAT Biology
A comprehensive introduction to key biological concepts tested on the MCAT, focusing on cellular processes, genetics, and the integration of biological systems.
Cellular Respiration and Metabolism
How Cells Harvest and Use Energy
Energy is essential for life, and cells extract it through metabolism. The main process for generating cellular energy is cellular respiration.
Stages of Cellular Respiration
- Glycolysis: Glucose is broken down in the cytoplasm, producing ATP and pyruvate.
- Krebs Cycle (Citric Acid Cycle): Pyruvate enters mitochondria, releasing electrons and more ATP.
- Electron Transport Chain: Electrons generate a proton gradient, driving ATP synthesis.
The overall equation is: \[ C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{ATP} \]
Metabolic Pathways
Catabolism breaks down molecules for energy, while anabolism builds new molecules.
Clinical Impact
Understanding metabolism helps explain diseases like diabetes, where energy extraction from glucose is impaired.
Key Formula
\[C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{ATP}\]
Examples
Muscle cells increase respiration during exercise to meet energy demands.
Mitochondrial disorders affect energy production, leading to fatigue.
In a Nutshell
Cellular respiration is how cells convert food to usable energy.