BIOS 251 Week 3 Case Study: Cells

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Chamberlain University

BIOS-251 Anatomy & Physiology I

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Date

Mitochondrial DNA and Its Significance

Brian notes that the mutation is located in a gene within the mitochondrial DNA, highlighting its significance. Mitochondrial DNA (mtDNA) is distinct from nuclear DNA and plays a critical role in cellular function. Brian’s reference to mtDNA relates to his brother’s diagnosis of Leber Hereditary Optic Neuropathy (LHON), a genetic condition that leads to vision loss. The mutation in the mitochondrial DNA may disrupt energy production, causing dysfunction in the optic nerve cells. The mitochondria, often termed the powerhouse of the cell, generate energy necessary for cell function. According to Gahl, “Mitochondria are membrane-bound organelles…that generate most of the chemical energy needed to power the cell’s biochemical reactions” (para. 1). This energy is stored in adenosine triphosphate (ATP), enabling the cell to perform vital biochemical reactions.

Composition and Function of Mitochondrial and Eukaryotic Cell Membranes

The mitochondrial membrane comprises two distinct layers: the outer and inner membranes. The outer membrane encases the organelle, while the inner membrane folds into structures called cristae, which enhance the surface area for ATP production. In comparison, the eukaryotic cell membrane consists of a bilayer of phospholipids. This membrane is integral in regulating the concentration of substances inside the cell, maintaining a stable internal environment. The structural differences between the mitochondrial and eukaryotic membranes reflect their specialized functions—energy production in mitochondria and selective permeability in eukaryotic cells.

Hypothesis on Vision Loss and Mitochondrial Dysfunction

The exact mechanism linking mitochondrial defects to optic nerve cell death remains unclear. However, a plausible hypothesis is that damaged mitochondria fail to produce sufficient ATP, resulting in cellular energy depletion and dysfunction. This energy deficit may trigger apoptosis, leading to optic nerve degeneration. Additionally, LHON is often inherited maternally due to the exclusive transmission of mitochondrial DNA from the mother. These factors combined likely contribute to the vision loss observed in conditions like LHON.