Eukaryotic Cell: Internal Structure
Information from Microbiology 4th Ed. by Marjorie Cowen
Nucleus: The Control Center
The nucleus is a compact sphere that is the most prominent organelle of eukaryotic cells. It is separated from the cytoplasm by a nuclear envelope. The nucleus contains the nucleolus which is the site of ribosomal RNA synthesis. In the nucleus's nucleoplasm, chromatin makes up chromosomes. Additionally, the nucleus contains DNA.
Endoplasmic Reticulum: A Passageway in the Cell
The endoplasmic reticulum is a microscopic series of tunnels used in transport and storage. There are rough (RER) and smooth (SER) kinds. An RER extended from the nuclear envelope to the outer membrane. The RER appears rough because of the ribosomes on the membrane surface. The SER does not have ribosomes to function in nutrient processing.
Golgi Apparatus: A Packaging Machine
The Golgi apparatus, also known as the Golgi complex or Golgi body, is the site where proteins are modified before being sent to their final destinations. It consists of a stack of several flat disc stacks. It is somewhat similar to the endoplasmic reticulum. The Golgi apparatus meets the endoplasmic reticulum and the endoplasmic reticulum buds off into transitional vesicles. In the apparatus, polysaccharides and lipids modify proteins.
Nucleus, Endoplasmic Reticulum, and Golgi body: An Assembly Line
The nucleus ultimately governs cell activities because it contains the eukaryotic genetic code. Since the nucleus cannot move, it must use a structural and chemical network consisting of the endoplasmic reticulums, the nuclear envelope, and the Golgi apparatus. Initially, a segment of the genetic code of DNA containing the instructions for producing a protein is copied into the RNA and passed out through the nuclear pores directly to the ribosome on the endoplasmic reticulum. Then, proteins are synthesized and deposited into the lumen. Finally, the proteins are moved to the Golgi apparatus where they are transformed and "packaged".
Mitochondria: Energy Generators of the Cell
The mitochondria is the primary energy producer of cells. The folds (cristae) hold the enzymes and electron carriers of aerobic respiration. This process extracts energy contained in nutrient molecules and stores it as ATP or high energy molecules. Interestingly, mitochondria divide independently of the cell.
Chloroplasts: Photosynthesis Machines
Chloroplasts are organelles found in algae and plant cells that convert sunlight into chemical energy through photosynthesis. Oxygen gas is also produced by photosynthesis. Oxygen gas is kind of important to people.
Ribosomes: Protein Synthesizers
Ribosomes are numerous tiny particles responsible for protein production that give a dotted appearance to the cytoplasm. Some are scattered through the cytoplasm/cytoskeleton and others are attached to the rough endoplasmic reticulum (RER). Others also appear in the mitochondria a chloroplasts. Eukaryotic ribosomes are similar to bacterial ribosomes.
Cytoskeleton: A Support Network
The cytoplasm of a eukaryotic cell is crisscrossed by a framework of molecules called the cytoskeleton. Its job is to anchor organelles, move RNA/vesicles, permit shape changes, and move some cells. The three main elements are actin filaments, intermediate filaments, and microtubules. Actin filaments are long and thing. Intermediate filaments are rope like. Microtubules are long, hollow tubes.
Survey of Eukaryotic Microorganisms
Eukaryotic microorganisms are nifty. Yeah.