Chapter 12: The Endomembrane System

These flashcards cover key vocabulary related to the endomembrane system, its components, functions, and related diseases as discussed in the lecture.

Endomembrane system

A group of membranes and organelles inside a eukaryotic cell.

Rough endoplasmic reticulum (RER)

Continuation of the nuclear membrane, studded with ribosomes, and site of protein synthesis.

Smooth endoplasmic reticulum (SER)

Synthesis of lipids, detoxification of drugs, and storage of calcium ions.

Cotranslational translocation

Process where proteins are either released into the ER lumen or embedded in the membrane during synthesis.

Golgi apparatus

Organelle that modifies, sorts, and transports proteins and lipids made in the ER.

Cisternae

Flattened, stacked membrane sacs in the Golgi apparatus.

Anterograde transport

Forward movement of molecules through the secretory pathway from the ER to the Golgi to the plasma membrane or lysosomes.

Retrograde transport

Movement of materials backward from the Golgi to the ER, often for recycling enzymes or returning misfolded proteins.

Endocytosis

Process by which the plasma membrane engulfs external substances by forming a vesicle.

Receptor-mediated endocytosis (RME)

Specialized endocytosis where the cell selectively takes in molecules using cell-surface receptors.

Clathrin

Structural protein that forms a lattice for coated vesicle formation during endocytosis.

Dynamin

An enzyme critical for pinching off vesicles during receptor-mediated endocytosis.

Lysosomes

Organelles that break down macromolecules, recycle old organelles, and digest foreign materials.

Exocytosis

Process by which vesicles fuse with the plasma membrane to release their contents outside the cell.

Glycosylation

Post-translational modification where sugar molecules are added to proteins or lipids.

N-linked glycosylation

Attachment of a sugar to the nitrogen atom of an asparagine side chain in a protein.

O-linked glycosylation

Attachment of a sugar to the oxygen atom of serine or threonine side chains in a protein.

Lysosomal storage diseases

Diseases caused by the inability to break down certain substrates due to enzyme deficiencies.

Pompe disease

A type II glycogenosis caused by deficiency of acid alpha-glucosidase leading to glycogen buildup.

Peroxisomes

Organelles that detoxify harmful substances and break down fatty acids.