Cellular Structure

• Nucleolus - A small structure within the nucleus responsible for producing ribosomes.
• The nucleus is the control center of the cell, containing genetic material (DNA) that determines an organism's characteristics.
• Ribosome - The site where protein synthesis occurs.
• Ribosome - The site where protein synthesis occurs, consisting of RNA molecules and proteins.
• Mitochondria - Organelles that produce energy through cellular respiration.
• Endoplasmic Reticulum (ER) - A network of membranes involved in protein synthesis and lipid metabolism.
• Vacuole - A fluid-filled sac used to store water or other materials.
• Endoplasmic Reticulum (ER): A network of flattened sacs called cisternae that are continuous with the nuclear envelope. It plays a role in protein synthesis and lipid metabolism.
• Lysosomes - Membrane-bound sacs filled with digestive enzymes used to break down waste materials inside cells.
• Golgi Apparatus - An organelle involved in modifying, sorting, and packaging proteins and lipids for transport to other parts of the cell or outside the cell.
• Lysosomes - Membrane-bound sacs filled with digestive enzymes used by cells to break down waste materials and invading pathogens.
• Cytoskeleton - A network of fibers made up of actin filaments, microtubules, and intermediate filaments that provides structural support and helps move substances within the cell.
• Golgi Apparatus: A stack of flattened sacs that modifies and packages proteins and lipids produced by the ER. It also sorts and transports these substances within the cell.
• Cellular structure is a whole new world.
• Microscopic differences include the view of the light microscope (LM) versus the electron microscope (EM), animal versus plant cells, and eukaryotic versus prokaryotic cells.
• Eukaryotes include four kingdoms: animals, plants, fungi, and protoctists.
• Eukaryotic cells have a distinct nucleus with a nuclear envelope and are usually larger than prokaryotic cells.
• Eukaryotic cells contain membrane-bound organelles with concurrent advantages.
• The point of organelles is compartmentalisation, division of labour, efficiency, and increased surface:volume (enzymes embedded within increases efficiency!).
• Increased rate of reactions is possible due to the proximity of reactants and specific conditions.
• Control of rate is possible through regulation of entry.
• Isolation of enzymes/reactants that could be damaging to cell function is possible.
• Organelles are functionally and structurally distinct regions of the cell, often membrane-bound.
• The ground substance of a cell is the cytoplasm, which is common to all cells and is the site of many cellular activities.
• Organelles float in a matrix of dissolved substances.
• The difference between cytoplasm and protoplasm is a matter of perspective.
• Proteases may release enzymes by exocytosis to the exterior.
• Proteases break down the contents of cells on death, a process known as autolysis, which is important post-pregnancy.
• Ribosomes are minute granules with a diameter of 20-25 nanometers, and they occur in eukaryotic cells but are smaller in prokaryotic cells.
• Ribosomes occur singly or in groups (polyribosomes), and are made up of protein and ribosomal RNA.
• Lysosomes are spherical and approximately 100 nanometers in diameter.
• Lysosomes are single-membrane-bound vesicles that are critical to prevent self-digestion of the cell.
• The role of ribosomes is to serve as the site of protein synthesis, providing a platform.
• Ribosomes have no membrane, consist of 2 subunits, and may occur free in the cytoplasm or on the RER.
• Proteases are enzymes that digest material consumed by a cell through phagocytosis or to digest worn-out organelles through autophagy.
• Centrioles are small, hollow, cylindrical paired organelles, arranged perpendicularly, located within the centrosome region of cytoplasm, next to the nucleus, 0.5 μm long, and comprised of 9 triplets of microtubules (made of tubulin, a protein).
• Differential centrifugation is a method used to isolate organelles to study structure or function.
• Cell fractionation is a method used to break apart cells and separate out organelles.
• There are four types of animal tissues: dermal ground vascular, organ, and epithelium.
• Cells must be kept cool (5 ºC), in isotonic solution, at specific pH (in buffer solution) during centrifugation.