Membrane Transport and Cell Biology Flashcards

Vocabulary flashcards covering active and bulk transport, phagocytosis mechanisms, receptor fates, pathogen entry, and phagocyte regulation.

Endocytotic-exocytotic cycle

The continuous exchange of plasma membrane in a cell, where membrane internalized through endocytosis is balanced by new membrane added via exocytosis to maintain a mostly constant cell size.

Phagocytosis

A regulated form of bulk transport where cell membrane receptors bind a particle, triggering pseudopods to surround and internalize it into a large vesicle called a phagosome.

Phagosome

A large intracellular vesicle formed when pseudopods fully enclose a target particle and pinch off internally from the plasma membrane.

Professional phagocytes

Specialized animal immune cells, such as macrophages, that perform phagocytosis to internalize and destroy pathogens, dead cells, and foreign debris.

Macrophages

Large white blood cells specialized in engulfing and breaking down foreign particles, pathogens, allergens, and nonfunctional or cancerous cells.

Pattern recognition receptors

Proteins located on the cell membrane or floating in the cytoplasm that bind to conserved pathogen or damaged-cell molecules to initiate phagocytosis.

PAMPs

Pathogen-associated molecular patterns; conserved molecules frequently found on pathogens that are recognized by pattern recognition receptors.

DAMPs

Damage-associated molecular patterns; conserved molecules associated with dead or damaged host cells that trigger phagocytic cleanup.

Opsonins

Extracellular proteins (such as antibodies) that bind to surface antigens on target particles or cells to mark them for phagocytosis.

MHC class I

A self-recognition protein expressed on living host cells that delivers inhibitory signaling to macrophages to prevent phagocytosis of healthy self cells.

Receptor recycling

A post-endocytic receptor fate where internalized membrane receptors (such as the LDL receptor at neutral pH) are returned back to the same plasma membrane domain.

Receptor degradation

A post-endocytic receptor fate where receptors and their bound ligands (such as EGF and the EGF receptor) are delivered to lysosomes for enzymatic breakdown.

Transcytosis

The endocytic pathway in which receptors and bound molecules (such as IgG via Fc receptors) are transported across a cell from one membrane domain to another.

Plasmodium falciparum

The malaria parasite that uses numerous surface proteins to trick red blood cells into allowing entry and evading the host immune response.

Phage therapy

The therapeutic application of bacteriophages to target and destroy bacteria, particularly in treating antibiotic-resistant bacterial infections.