Chapter 1 - Leaf Cells Consist of Several Metabolic Compartments

Abstract

In higher plants photosynthesis occurs mainly in the mesophyll—the chloroplast-rich tissue of leaves. The cellular contents are surrounded by a plasma membrane, called plasmalemma, and are enclosed by a cell wall. The cell contains organelles, each with its own characteristic shape, which separate the cell into various compartments (subcellular compartments). Each compartment has specialized metabolic functions, which are discussed in detail in the following chapters. The largest organelle, the vacuole, usually fills about 80% of the total cell volume. Chloroplasts represent the next largest compartment. The number of chloroplasts per cell varies depending on the cell type and developmental stage. Further cellular compartments include the mitochondria, peroxisomes, nucleus, endoplasmic reticulum, and Golgi bodies; all organelles reside in the cytosol, thus cytosol and organelles represent the cytoplasm. In addition, oil bodies derive from the endoplasmic reticulum. These oil bodies, which occur in seeds and some other tissues (e.g., root nodules), are storage organelles for triacylglycerides.