Endomembrane system & bulk transport processes Flashcards
form compartments in the cell
What is the endomembrane system?
A system of interconnected membranes within the cell, including organelles like the nuclear envelope, ER, Golgi apparatus, vesicles, lysosomes, and the plasma membrane.
What are the two types of bulk transport?
Exocytosis (out of the cell) and Endocytosis (into the cell).
What is exocytosis?
The process of transporting materials out of the cell via vesicles that fuse with the plasma membrane.
What are the two types of exocytosis?
Constitutive exocytosis – continuous release of extracellular matrix proteins.
Regulated exocytosis – controlled release triggered by signals (e.g., neurotransmitters).
What is endocytosis?
The process where a cell engulfs molecules or particles from the extracellular environment via vesicles.
What are the three types of endocytosis?
Phagocytosis (“cell eating”) – uptake of large particles or food.
Pinocytosis (“cell drinking”) – uptake of extracellular fluid and solutes.
Receptor-mediated endocytosis – selective uptake of specific molecules via receptor proteins.
What are the two types of the endoplasmic reticulum (ER)
Rough ER (RER) – has ribosomes, synthesizes proteins.
Smooth ER (SER) – lacks ribosomes, involved in lipid synthesis, detoxification, and calcium storage.
What are the functions of the smooth ER?
Metabolism of carbohydrates
Lipid synthesis for membranes
Detoxification of drugs and poisons
Storage of calcium ions
What is the function of the Golgi apparatus?
Modifies, sorts, and ships proteins received from the rough ER.
What are the two faces of the Golgi apparatus?
Cis face – receives vesicles from the ER.
Trans face – ships processed proteins to their final destination.
What is glycosylation?
The process of adding carbohydrates to proteins, which occurs in the Golgi.
What is a vesicle?
A small, membrane-bound organelle that transports materials within the cell.
How does the Golgi direct vesicle trafficking?
By adding molecular tags (often proteins) that help vesicles reach the correct target.
What are the types of vesicles?
Transport vesicles
Secretory vesicles
Vacuoles (larger vesicles, mainly in plants)
What are lysosomes?
Membrane-bound organelles containing hydrolytic enzymes for digestion and recycling.
What is the function of lysosomes?
Break down proteins, lipids, carbohydrates, and nucleic acids.
Recycle cellular materials via autophagy.
Why do lysosomes require an acidic environment?
Their hydrolytic enzymes only function in low pH conditions.
What are vacuoles?
Large vesicles derived from the ER and Golgi, mainly found in plant cells.
What are the functions of vacuoles?
Store nutrients and waste.
Absorb water to help the plant cell grow.
Maintain cell structure by exerting pressure.
