Compartmentalization in Eukaryotic Cells (College Board AP® Biology): Study Guide

Cells have membranes that allow them to establish and maintain internal environments which are different from their external environments

Within cells, there are membrane-bound organelles that achieve compartmentalization on a smaller scale

This allows separate metabolic reactions to take place in different regions of the cell

Membranes contain membrane proteins, many of which are enzymes that perform their catalytic role at the membrane or just to one side of it

Membrane-bound organelles occur in eukaryotic cells and have key benefits to the cell

• They allow compartmentalization within a cell

  • E.g. allowing the reaction of glycolysis to be kept separate (in the cytosol) from those of the Krebs cycle and oxidative phosphorylation (inside mitochondria)

  • This allows a cell to utilize chemical respiration even in the temporary absence of oxygen

• To keep various reactions separate from each other

  • This minimizes the risk of conflicting side reactions occurring, that would have no metabolic benefit

  • This also minimizes the risk of enzyme reactions being accidentally inhibited by substrates and products from other biochemical pathways

• Cells can increase the internal surface area for reactions by housing important membrane proteins within the membranes that surround organelles

  • Cells that have a high requirement for ATP, such as muscle cells, can produce more mitochondria to provide greater number of reactions within electron transport chains to produce ATP

  • Cells that have an active role in the secretion of proteins, such as insulin-producing cells in the pancreas, can increase the number of ribosomes / rough ER / Golgi to meet the demand for secreted insulin

  • Cells with a role in removal of waste, such as neutrophils and monocytes, can produce more lysosomes to fulfil their role more effectively