Chapter 3: Cell Membrane Transport and Endomembrane System Flashcards

A set of 30 vocabulary flashcards reviewing key concepts, organelles, and membrane transport processes covered in Chapter 3.

Integral membrane protein

A protein that spans the lipid bilayer (transmembrane) and is exposed to the aqueous environment on both sides of the membrane.

Peripheral membrane protein

A protein located on the surface of the cell membrane through interactions with integral membrane proteins or lipid head groups.

Homeostasis

The active maintenance of a constant internal environment within a cell or organism.

Simple diffusion

The passive movement of solute molecules across a permeable membrane directly from an area of higher concentration to an area of lower concentration without energy or transport proteins.

Osmosis

The passive movement of water across a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration.

Facilitated diffusion

The passive movement of molecules down their concentration gradient across a membrane through channel or carrier proteins.

Primary active transport

An energy-requiring transport process that uses energy directly (such as ATP) to move molecules against their concentration gradient, as seen in the $Na^+/K^+$ pump.

Secondary active transport

A transport process where the movement of a molecule against its concentration gradient is driven by an electrochemical gradient generated by primary active transport.

Contractile vacuole

A specialized organelle found in single-celled protists that collects and expels excess water to maintain cellular shape and osmotic balance.

Turgor pressure

The force pushing the plasma membrane against the cell wall in cells with cell walls, caused by the osmotic inflow of water.

Endomembrane system

An interconnected set of membranes in eukaryotic cells that defines distinct functional spaces and compartments.

Vesicle

A small membrane-bound sac that buds off from an organelle, carries cellular materials, and fuses with other organelle or cellular membranes.

Exocytosis

The cellular process in which contents within an internal vesicle are released outside the cell upon vesicle fusion with the plasma membrane.

Endocytosis

The cellular process in which external molecules or materials are taken up into the cell through the invagination and pinching off of the plasma membrane into a vesicle.

Phagocytosis

A specific form of endocytosis in which a cell engulfs large particles or food into a vacuole, which then fuses with a lysosome for digestion.

Pinocytosis

A specific form of endocytosis in which dissolved molecules in extracellular fluid are engulfed in tiny vesicles.

Receptor-mediated endocytosis

A selective form of endocytosis triggered when specific extracellular ligands bind to designated cell surface receptors.

Ligand

Any specific molecule that binds specifically to a complementary receptor site of another molecule.

Cytoplasm

The internal contents of the cell excluding the nucleus, comprising the cytosol and all internal structures or organelles.

Cytosol

The semifluid, jelly-like internal environment of the cell surrounding the organelles inside the plasma membrane.

Nuclear envelope

A double membrane structure, consisting of inner and outer membranes, that defines the boundaries of the nucleus.

Nuclear pore

A membrane protein opening spanning both membranes of the nuclear envelope that regulates movement of molecules into and out of the nucleus.

Ribosome

A cellular structure that serves as the site of protein synthesis, assembling amino acids into polypeptides guided by mRNA.

ER lumen

The continuous fluid-filled interior compartment enclosed within the membranes of the endoplasmic reticulum.

Rough endoplasmic reticulum

The portion of the endoplasmic reticulum associated with ribosomes that processes membrane, organelle-targeted, and secreted proteins.

Smooth endoplasmic reticulum

The portion of the endoplasmic reticulum lacking ribosomes that serves as the primary site for lipid and carbohydrate biosynthesis and drug/poison detoxification.

Golgi apparatus

An organelle consisting of stacks of membrane-bound cisternae that further modifies, sorts, and packages proteins and lipids from the ER.

Glycosylation

The enzymatic modification process in which sugars are covalently attached to proteins (forming glycoproteins) or lipids (forming glycolipids).

Lysosome

A specialized vesicle derived from the Golgi apparatus containing hydrolytic enzymes maintained at an acidic pH of $5$ to degrade macromolecules.

Peroxisome

An organelle containing enzymes that metabolize long-chain fatty acids and detoxify substances by converting hydrogen peroxide ($H_2O_2$) to water and oxygen.