Structural Biochemistry/Functional Categories of Eukaryotic Organelles
All the different membranous organelles perform different tasks in the cell (animal cells and plant cells). However, they also communicate with each other though ions and lipids. In addition, some of the organelles have membrane that are connected. The others are related by transfer of membrane segments. As we know, structures determine functions in a lot of ways in nature. We can categorize eukaryotic organelles into four categories according to their general functions.
In this first category, nucleus, ribosomes, rough ER, smooth ER and golgi apparatus are included. They can perform this task because of they have metabolically active membranes. Some of them can also perform transportation of the products. Below is some examples of the manufacturing task these organelles do.
- Nucleus--DNA and RNA synthesis
- Ribosome--Polypeptide(protein) synthesis
- Rough ER--Membrane protein synthesis, secretory proteins synthesis and hydrolytic enzymes synthesis; formation of transport vesicles
- Smooth ER--Lipid synthesis; detoxification and carbohydrate metabolism in liver cells
- Golgi apparatus--Modificaiton, temporary storage and transportation of macromolecules such as proteins; formation of lysosomes and transport vesicles
In this category, lysosomes, peroxisomes and vacuoles are included. They are all consist of single membrane sac that can be used to collect materials and/or break down unwanted/harmful materials.
- Lysosomes--Digestion of bacteria, damaged organelle
- Peroxisomes--breakdown of H2O2 by-product
- Vacuoles--Digestion of waste products; collect excess water from the cell
In this category, chloroplasts and mitochondria are included. They both have metabolically active membranes and intermembrane compartments that can convert energy units to provide to the cells.
- Chloroplast--Conversion of light energy to chemical energy in plant cells
- Mitochondria--Conversion of chemical energy of food to chemical energy of ATP
Support, Movement and Communication between cells
In this last category, cytoskeleton(such as cilia, flagella and centrioles in animal cells), cell walls(in plants, fungi and some protists), extracellular matrix(in animal cells) and cell junctions are included. They are all responsible for the keeping cells in shape.
- Cytoskeleton--Maintenance of cell shape; movement of organelles within cells; cell movement; mechanical transmission of signals from exterior of cell to interior
- Cell walls--Maintenance of cell shape and skeletal support; surface protection; binding of cells in tissue
- Extracellular matrix--Binding of cells in tissues; surface protection; regulation of cellular activities
- Cell junctions--Communication between cells; binding of cells in tissues
Neil A. Campbell, Jane B. Reece, Martha R.Taylor, Eric J. Simon, Jean L.Dickey. Biology: Concepts and Connections. 6th edition. San Fransico: Benjamin Cummings. 2008