Cell Physiology Vocabulary Flashcards

A set of 50 vocabulary flashcards covering cell structure, organelles, plasma membrane properties, and cytoskeletal components based on Cell Physiology lecture notes.

Cell

The basic structural and functional unit of the human body that serves as the cellular basis for the continuity of life.

Plasma Membrane

The flexible outer boundary separating the intracellular fluid from the extracellular fluid, also known as the cell membrane.

Fluid Mosaic Model

A structural description of the plasma membrane as an extremely thin ($7-10\,\text{nm}$) lipid bilayer with dispersed, floating protein molecules forming a mosaic pattern.

Hydrophilic Polar Head

The charged end of a phospholipid molecule that is attracted to water and lies on the inner and outer surfaces of the membrane.

Hydrophobic Nonpolar Tail

The uncharged central region of a phospholipid molecule made of two fatty acid chains that avoids water.

Glycolipid

A lipid with attached sugar groups found exclusively on the outer membrane surface, accounting for $5\%$ of total membrane lipids.

Cholesterol

A membrane lipid comprising $20\%$ of total membrane lipids that stabilizes the membrane and decreases phospholipid mobility and membrane fluidity.

Integral Proteins

Membrane proteins firmly inserted into the lipid bilayer, mostly existing as transmembrane proteins that span the entire membrane width.

Peripheral Proteins

Proteins attached to integral proteins or filaments that function as enzymes, motor proteins during cell division, or intercellular links.

Lipid Rafts

Dynamic, stable, and less fluid membrane microdomains composed of phospholipids, sphingolipids, and cholesterol that concentrate receptor and signaling proteins.

Caveolae

Small, flask-shaped invaginations of the plasma membrane enriched in caveolin that represent a specific type of lipid raft.

Planar Lipid Rafts

A type of lipid raft found in neurons that is enriched in the protein flotillin.

Glycocalyx

The fuzzy, sticky, carbohydrate-rich region on the outer cell surface that provides biological markers for cell-to-cell recognition.

Cytosol

The viscous, semitransparent fluid portion of the cytoplasm containing water, dissolved proteins, salts, and sugars.

Inclusions

Chemical substances stored in cytoplasm depending on cell type, including glycogen granules, lipid droplets, melanin granules, and crystals.

Mitochondria

Membranous organelles functioning as cellular power plants that generate most of the cell's ATP supply through aerobic cellular respiration.

Cristae

Shelf-like inward folds of the inner mitochondrial membrane where enzymes involved in oxidative phosphorylation reside.

Mitochondrial Fission

The process in which mitochondria pinch in half to increase their number when cellular demand for ATP increases.

Ribosomes

Small granules composed of proteins and ribosomal RNAs that act as the primary sites of cellular protein synthesis.

Free Ribosomes

Unattached cytoplasmic ribosomes that synthesize soluble proteins used in the cytosol or imported into organelles.

Membrane-bound Ribosomes

Ribosomes attached to the rough ER that synthesize proteins destined for cell membranes, lysosomes, or export from the cell.

Rough Endoplasmic Reticulum

A ribosome-studded membranous organelle that manufactures secreted proteins, integral membrane proteins, and membrane phospholipids.

Smooth Endoplasmic Reticulum

A network of membranous tubules that synthesizes lipids, cholesterol, and steroid hormones, metabolizes fats, and detoxifies drugs and pesticides.

Sarcoplasmic Reticulum

An elaborate form of smooth ER found in skeletal and cardiac muscle cells that stores and releases calcium ions during contraction.

Golgi Apparatus

A system of stacked, flattened membranous sacs that acts as the principal traffic director to modify, concentrate, and package proteins and lipids.

Cis Face

The receiving side of the Golgi apparatus where transport vesicles arriving from the rough ER fuse with the membrane.

Trans Face

The shipping side of the Golgi apparatus from which secretory vesicles, plasma membrane vesicles, and lysosomes pinch off.

Peroxisomes

Spherical membranous sacs containing oxidases and catalases that detoxify harmful substances and neutralize free radicals.

Free Radicals

Highly reactive metabolic by-products with unpaired electrons that can cause damage to cellular biological molecules.

Oxidases

Peroxisomal enzymes that use molecular oxygen to detoxify harmful substances and convert free radicals into hydrogen peroxide.

Catalases

Peroxisomal enzymes that rapidly convert dangerous hydrogen peroxide into water.

Lysosomes

Spherical membranous organelles containing acid hydrolases that digest endocytosed material, damaged organelles, and cell debris.

Acid Hydrolases

Digestive enzymes contained within lysosomes that operate best under acidic conditions.

Autolysis

The self-digestion of a cell caused by the widespread rupture of its lysosomes when injured or deprived of oxygen.

Tay-Sachs Disease

An inherited condition where lysosomes lack an enzyme needed to break down a glycolipid in nerve cell membranes, leading to nervous system failure.

Endomembrane System

An interconnected system of organelles including the ER, Golgi apparatus, vesicles, lysosomes, and nuclear membrane that produce, store, and export biological molecules.

Cytoskeleton

An unencapsulated network of protein rods running through the cytosol that supports cell structures and generates cellular movements.

Microfilaments

The thinnest cytoskeletal elements ($7\,\text{nm}$ diameter), composed of actin subunits that facilitate cell motility and shape changes.

Terminal Web

A dense cross-linked network of microfilaments attached to the inner plasma membrane that strengthens the cell surface.

Intermediate Filaments

Tough, insoluble protein fibers ($10\,\text{nm}$ diameter) formed of tetramer subunits that act as internal wires to resist mechanical forces.

Neurofilaments

The specific name given to intermediate filaments located within nerve cells.

Keratin Filaments

The specific name given to intermediate filaments located within epithelial cells.

Microtubules

The largest cytoskeletal elements ($25\,\text{nm}$ diameter), composed of hollow tubulin tubes radiating from the centrosome to determine overall cell shape.

Motor Proteins

ATP-powered proteins such as kinesins and dyneins that walk organelles and vesicles along microtubule pathways.

Centrosome

The microtubule organizing center near the nucleus containing a matrix and paired centrioles.

Centrioles

Small, barrel-shaped organelles composed of nine triplets of microtubules arranged in a hollow tube, oriented at right angles within the centrosome matrix.

Basal Bodies

Centrioles that have positioned themselves beneath the plasma membrane to form the structural foundations of cilia and flagella.

Cilia

Motile surface extensions featuring a "$9+2$" pattern of microtubules that move substances in a single direction across cell surfaces.

Dynein Arms

Motor protein projections attached to ciliary microtubule doublets that exert ATP-powered forces to cause ciliary bending.

Microvilli

Minute, fingerlike projections of the plasma membrane containing an actin filament core that increase surface area for cellular absorption.