Lecture 8: Endomembrane System Vocabulary

Flashcards covering key vocabulary and concepts related to the endomembrane system, including its components, functions, and processes like glycosylation and protein targeting.

Endomembrane System

Comprises the nuclear envelope, Golgi apparatus, plasma membrane, lysosome, endoplasmic reticulum (smooth and rough), and vacuoles in plant cells and fungi. These components communicate via vesicles.

Endoplasmic Reticulum (ER)

An extensive membranous network within eukaryotic cells, continuous with the outer nuclear membrane, consisting of interconnected tubules and flattened sacs.

Rough Endoplasmic Reticulum (Rough ER)

The region of the endoplasmic reticulum that is studded with ribosomes and engages in protein synthesis and modification.

Smooth Endoplasmic Reticulum (Smooth ER)

The portion of the endoplasmic reticulum that is free of ribosomes and is involved in lipid synthesis, detoxification, and calcium storage.

Functions of Smooth ER

Stores calcium ions, synthesizes lipids (phospholipids and steroids), and detoxifies poisons (e.g., alcohol).

Glycosylation

The addition of carbohydrate groups to proteins and lipids, occurring in the endoplasmic reticulum and Golgi apparatus.

Signal Peptide

A short sequence of amino acids, usually at the N-terminus of a polypeptide, that directs the ribosome and its associated mRNA to the endoplasmic reticulum membrane.

Signal Recognition Particle (SRP)

A protein-RNA complex that recognizes the signal peptide and escorts the ribosome and its associated mRNA to the endoplasmic reticulum (ER) membrane, halting translation temporarily.

Transport Vesicle

A membranous sac within the cytoplasm of a eukaryotic cell

Golgi Apparatus

An organelle in eukaryotic cells functioning in processing and packaging proteins and lipids; consists of flattened stacked sacs (cisternae)

Exocytosis

The process by which a cell releases large amounts of substances by the fusion of vesicles with the plasma membrane.