Metabolic Conditions Regulate Mitochondrial Volume Scaling in Budding-Inhibited Saccharomyces cerevisiae
Aya Alkabbani
Department of Biology
Faculty Supervisor: Mark Chan
Cell size and organelle architecture are tightly regulated by cellular metabolism and environmental conditions. In this study, we investigated how different carbon sources influence mitochondrial organization and cell morphology in Saccharomyces cerevisiae when budding is inhibited. Yeast cells were grown in synthetic complete (SC) media containing glucose, raffinose, galactose, or fructose, and organelle structure was visualized using fluorescence microscopy. When budding was inhibited, cells continued to increase in size over time, leading to enlargement of intracellular organelles. Across all growth conditions, mitochondrial volume increased proportionally with cell volume, demonstrating a scaling relationship between mitochondrial content and overall cell size. However, the extent of mitochondrial expansion varied depending on the carbon source. Cells grown in glucose showed the largest mitochondrial volumes and the strongest scaling relationship with cell size, consistent with higher metabolic activity and rapid growth. Cells grown in galactose and fructose exhibited moderate mitochondrial expansion, while raffinose-grown cells showed the lowest mitochondrial volumes and slower growth. Microscopy images further revealed dynamic changes in mitochondrial morphology, including the formation of larger and more interconnected mitochondrial networks as cells enlarged. Together, these results demonstrate that mitochondrial volume scales with cell size during growth but is significantly influenced by the available carbon source. This work highlights how metabolic conditions regulate organelle architecture and provides insight into the coordination between cellular growth, metabolism, and mitochondrial organization.