Problem 1 - AP Psychology Premium Prep 2021

Question

The mitochondrion is a critical organelle structure involved in cellular respiration. Below is a simple schematic of the structure of a mitochondrion. Which of the structural components labeled below in the mitochondrion is the primary location of the Krebs cycle? (A) Inner membrane (B) Matrix (C) Intermembrane space (D) Outer membrane

Step-by-Step Solution

Answer

The primary location of the Krebs cycle in the mitochondrion is the matrix (B). This is where the oxidative metabolism of Acetyl-CoA occurs through a series of enzyme-catalyzed reactions.

Step 1: Understand the Krebs cycle

The Krebs cycle, also known as the citric acid cycle or the tricarboxylic acid cycle, is a series of chemical reactions that generates energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins. The Krebs cycle is an aerobic metabolic pathway that occurs inside the mitochondria.

Step 2: Explore the structure of a mitochondrion.

A mitochondrion is a membrane-bound organelle found in the cytoplasm of eukaryotic cells. It consists of four main structural components: 1. Inner membrane: a highly folded membrane with extensive surface area that contains proteins for the electron transport chain (ETC) and ATP synthesis. 2. Matrix: the enzyme-rich fluid-filled space enclosed by the inner membrane where the Krebs cycle takes place. 3. Intermembrane space: the narrow space between the inner and outer membrane, where protons accumulate during the ETC, creating a proton gradient used for ATP synthesis. 4. Outer membrane: a porous membrane that separates the contents of the mitochondrion from the surrounding cytoplasm.

Step 3: Identify the primary location of the Krebs cycle

From the mitochondrial structural components and the information about the Krebs cycle, we can determine that the primary location of the Krebs cycle is within the matrix. The Krebs cycle contains a series of enzyme-catalyzed reactions that occur in the matrix, and this is where the oxidative metabolism of the Acetyl-CoA takes place. So, the correct answer is: (B) Matrix