Cellular Form and Function Flashcards

Vocabulary flashcards covering cellular structure, membrane functions, transport mechanisms, and organelle roles based on Chapter 3 lecture notes.

Cytology

The scientific study of cells.

Robert Hooke

The scientist who coined the word cellulae to describe empty cell walls of cork in the 17th century.

Theodor Schwann

The scientist who concluded that all animals are made of cells.

Louis Pasteur

The scientist who demonstrated that cells arise only from other cells.

Cell Theory

The foundational biological theory stating that all organisms are composed of cells and cell products, cells are the simplest structural and functional units of life, and cells come only from preexisting cells.

Plasma Membrane

The selectively permeable membrane surrounding the cell, composed of lipids and proteins, that defines cellular boundaries and controls the passage of materials.

Cytosol

The intracellular fluid (ICF) contained within the cytoplasm of a cell.

Extracellular Fluid (ECF)

Fluid located outside of cells, which includes tissue (interstitial) fluid.

Integral Proteins

Membrane proteins that penetrate completely through the phospholipid bilayer, possessing hydrophilic regions contacting ECF/ICF and hydrophobic regions contacting membrane lipids.

Peripheral Proteins

Membrane proteins that adhere to one side of the plasma membrane and are typically tethered to the cytoskeleton.

Ligand-Regulated Gates

Gated protein channels in the plasma membrane that open or close in response to chemical messengers.

Voltage-Regulated Gates

Gated protein channels in the plasma membrane that open or close in response to electrical charge differences across the membrane.

Mechanically Regulated Gates

Gated protein channels in the plasma membrane that open or close in response to physical stretch or pressure.

Microvilli

Extensions of the plasma membrane specialized for absorption that can form a dense brush border on cell surfaces.

Cilia

Hair-like processes extending from the cell surface; motile cilia beat in coordinated waves using power and recovery strokes to move material across the cell surface.

Flagellum

A long, whip-like surface extension found on sperm tails, stiffened by coarse fibers, that produces undulating snakelike movements for cell locomotion.

Pseudopods

Continually changing surface extensions of the cell that vary in shape and size, utilized for cellular locomotion and capturing foreign particles.

Filtration

A passive transport process in which water and solutes are driven through a selectively permeable membrane by hydrostatic pressure.

Simple Diffusion

The net movement of particles from an area of high concentration to an area of low concentration down their concentration gradient without carrier proteins.

Osmosis

The net flow of water across a selectively permeable membrane through aquaporins from a region of higher water concentration to lower water concentration.

Osmolarity

The total concentration of all dissolved solute particles in a solution, measured in osmoles per liter ($\text{osm/L}$); normal body fluids measure $300\,\text{mOsm/L}$.

Tonicity

The ability of a surrounding solution to affect fluid volume and pressure in a cell.

Hypotonic Solution

A solution with a lower concentration of non-permeating solutes than the intracellular fluid, causing cells to absorb water and swell.

Hypertonic Solution

A solution with a higher concentration of non-permeating solutes than the intracellular fluid, causing cells to lose water and shrivel (crenate).

Isotonic Solution

A solution in which the solute concentration equals that of the intracellular fluid, producing no change in cell volume.

Transport Maximum ($T_m$)

The maximum rate of carrier-mediated transport achieved when all membrane transport proteins are fully saturated with solute molecules.

Uniport

A carrier protein that transports only one specific type of solute across the plasma membrane.

Symport

A carrier protein involved in cotransport that moves two or more solutes simultaneously in the same direction across the membrane.

Antiport

A carrier protein involved in countertransport that moves two or more solutes in opposite directions across the membrane.

Facilitated Diffusion

Carrier-mediated transport of a solute across a membrane down its concentration gradient without consuming ATP.

Primary Active Transport

Carrier-mediated transport that moves solutes up their concentration gradient while directly consuming ATP.

Secondary Active Transport

Carrier-mediated transport that moves solutes up their concentration gradient using ATP indirectly by relying on ion gradients generated by primary active transport.

Phagocytosis

A form of endocytosis in which a cell surrounds and engulfs large foreign particles using pseudopods ('cell eating').

Pinocytosis

A form of endocytosis in which the plasma membrane dimples and pinches off vesicles containing droplets of extracellular fluid ('cell drinking').

Receptor-Mediated Endocytosis

Selective endocytosis where specific target molecules bind to cell-surface receptors and are internalized in clathrin-coated vesicles.

Exocytosis

A vesicular transport process in which secretory vesicles move to the cell surface, fuse with the plasma membrane, and discharge their contents outside the cell.

Cytoskeleton

An intracellular network of protein filaments and cylinders (microtubules, microfilaments, intermediate filaments) providing structural support, cell shape, and internal transport.

Nucleus

The largest organelle (approximately $5\,\mu\text{m}$ in diameter) surrounded by a double membrane nuclear envelope, containing nucleoplasm, chromatin, and the nucleolus.

Ribosomes

Non-membranous organelles composed of protein and RNA that translate messenger RNA and assemble amino acids into proteins.

Rough Endoplasmic Reticulum

An organelle composed of parallel, flattened membrane sacs studded with ribosomes, responsible for synthesizing membrane phospholipids and proteins.

Smooth Endoplasmic Reticulum

A tubular membrane network lacking ribosomes that synthesizes steroids and lipids, detoxifies drugs and alcohol, and stores calcium ions.

Golgi Complex

A system of flattened membrane cisternae that modifies, sorts, and packages newly synthesized proteins from the rough ER into membrane-bound vesicles.

Lysosomes

Membrane-bound sacs containing digestive enzymes that perform intracellular digestion, autophagy, and autolysis.

Autophagy

The lysosomal process of digesting and recycling a cell's surplus or worn-out organelles.

Autolysis

The process of cellular self-digestion ('cell suicide') carried out by lysosomal enzymes.

Peroxisomes

Enzyme-containing organelles abundant in liver and kidney cells that neutralize free radicals, detoxify toxins, and break down fatty acids.

Proteasome

A hollow cylindrical barrel-shaped organelle containing enzymes that degrade tagged surplus proteins into short peptides and amino acids.

Mitochondria

Double-membrane bound organelles specialized for ATP synthesis, featuring internal membrane folds called cristae and an internal matrix.

Centrioles

Short cylindrical assemblies of microtubules arranged in pairs that play critical roles in cell division and the formation of cilia and flagella.