Definition:
The term 'endoplasmic' refers to 'inside the cytoplasm' and 'reticula' means 'little net'.
Described as small net-like structures observed under a microscope, now recognized as a series of tubes that function like a sewer system inside the cell.
Characteristics:
Named 'rough' due to the presence of ribosomes on its surface, which appear as brownish blobs in electron microscope images.
Ribosomes dock on the Rough ER's ports, facilitating protein synthesis.
Function:
Ribosomes synthesize proteins, which are then deposited into the Rough ER for processing.
Responsible for the proper folding of proteins; cells heavily involved in protein production have an abundance of ribosomes and Rough ER.
Characteristics:
Lacks ribosomes, resulting in a smooth appearance under an electron microscope.
Found in specific cells, such as:
Ovarian cells producing estrogen.
Testicular cells producing testosterone.
Liver cells filled with detoxification enzymes.
Function:
Smooth ER plays a key role in detoxifying substances that enter the body through the digestive system.
These substances are processed and monitored before reaching vital organs (e.g., brain).
In heavy drinkers, liver cells (hepatocytes) accumulate Smooth ER, leading to potential dysfunction as other organelles are crowded out.
Overview:
Sometimes called Golgi complex, it is involved in modifying, sorting, and shipping proteins and other molecules received from the ER.
Process:
Preprocessed products from the Rough and Smooth ER are transported to the Golgi for further modification.
Example: Insulin synthesis begins in the Rough ER as preinsulin, which is a large molecule with an active hormone segment.
The preinsulin moves through various compartments of the Golgi, undergoing modifications in different pH and enzymatic conditions.
Structure:
Composed of layers analogous to flat pita breads, with vesicles exiting the trans face after sorting and modification.
The cyst face of the Golgi faces the ER, while the trans face is aligned with the secretion pathway.
Final Export:
Once fully modified, insulin is encapsulated in a vesicle and released into the bloodstream to function as a hormone.
Overview:
Lysosomes are considered the digestive organelles of the cell, containing hydrolytic enzymes that promote hydrolysis reactions.
Functionality:
Lysosomes can digest proteins (proteases), carbohydrates (carbohydrases), and nucleic acids (nucleases) by breaking down their respective biomolecules.
If an organelle, like a malfunctioning mitochondrion, is detected, lysosomes fuse with its vesicle to digest it into basic components (amino acids, monosaccharides, etc.) for reuse.
Primarily involved in the immune response by breaking down dead cells and debris in the body.
Overview:
Vacuoles in plant cells and vesicles in animal cells are membrane-bound storage sacs within the cytoplasm.
Plant Cells:
Plants possess a large central vacuole that stores nitrogenous waste, which prevents the buildup of toxins.
As the concentration of solutes increases within the vacuole, water rushes in and helps maintain turgor pressure, allowing plants to stand upright against gravity.
Function in Water Regulation:
Certain protozoa have contractile vacuoles that act like a bilge pump to expel excess water from inside the cell, thus preventing it from bursting due to increased internal pressure.
Importance:
Though not as dynamic as other organelles, vacuoles and vesicles play crucial roles in storage and maintenance of cell stability, particularly in plants and protozoa.