Organization of Organelles
By: Bailey Glenn
Most prominent place of the Eukaryotic cell, is the nucleus. It is seperated from the cell cytoplasm by an external boundary called a nuclear envelope. The nucleus contains an inner substance called the nucleoplasm, and a granular mass, the nucleolus. The nucleolus is a site for ribosomal RNA synthesis and a collection area for ribosomal subunits.
The ER is microscopic series of tunnels used in transport and storage. There are two kinds of ER's; one being the Rough Endoplasmic reticulum and Smooth Endoplasmic Reticulum. The RER, is on the outer membrane of the nuclear envelope and extends in a continuous network through the cytoplasm. The SER is a closed tubular network without ribosomes that serves in nutrient processing and in synthesis and storage of non protein macromolecules such as lipids.
Golgi Apparatus is a packaging machine. It is the site in which proteins are modified and then sent to their final destinations. It is a discrete organelle made up of a stack of many flattened, disc-shaped sacs, or cisternae. This organelle is closely associated with the ER both in its location, as well as its function.
The Mitochondria serves as the energy generators of the cell. The bulk of energy which is made in the eukaryote cell is by the Mitochondria. They appear as round or elongated particles scattered throughout the cytoplasm. It consists of a smooth, continuous outer membrane that forms the external contour, and an inner, folded membrane nestled neatly within the outer membrane. The folds on the inner membrance are called cristae. The spaces around the cristae are filled with a chemically complex fluid called the matrix. The function of the matrix is to hold ribosomes, DNA, and the pool of enzymes and other compounds involved in the metabolic cycle.
Chloroplasts are remarkable organelles found in algae and plant cells that are capable of converting the energy of sunlight into chemical energy through the process of photosynthesis. There is a smooth, outer membrane in addition to an inner membrane.
Tiny particles that give a dotted appearance to the cytoplasm. Ribosomes are distributed throughout the cell, some scattered are dispersed freely in the cytoplasm and cytoskeleton; while others are attached to the rough endoplasmic reticulum. Ribosomes are often arranged in chains, these are called poly-ribosomes. The overall job of ribosomes are too serve as a stage for protein synthesis.
The cytoskeleton is a flexible framework of molecules that crisscross the cytoplasm of a eukaryotic cell. The function of this includes: achoring organelles, moving RNA an vesicles, and permitting shape changes and movement in some cells. There are 3 types of cytoskeleton which are action filaments, intermediate filaments, and microtubules. Action filaments are long, thin, protein strands about 7 nanometers in diameter. They are responsible for cellular movements such as contraction, crawling, pinching during cell division, and formation of cellular extensions. Microtubules are long, hollow tubes that maintain the shape of eukaryotic cells when they dont have walls and transport substances form one part of a cell to another. Intermediate filaments are ropelike structures that are about 10 nanometers in diameter. Their main role is in structural reinforcement of the cell and of organelles. For example, they support the structure of the nuclear envelope.