Chapter 03: Cellular Form and Function Vocabulary Flashcards

Vocabulary flashcards covering cell shapes, organelles, membrane transport mechanisms, cell surface structures, and vesicular transport based on Chapter 3.

Common Cell Shapes

The varied shapes of human cells including Squamous, Cuboidal, Columnar, Polygonal, Stellate, Spheroidal, Discoidal, Fusiform, and Fibrous.

Squamous

A thin, flat, scaly cell shape.

Cuboidal

A squarish-looking cell shape.

Columnar

A cell shape that is taller than wide.

Polygonal

A cell shape characterized by irregularly angular shapes with multiple sides.

Stellate

A starlike cell shape.

Spheroid or Ovoid

A round to oval cell shape.

Discoidal

A disc-shaped cell shape.

Fusiform

A spindle-shaped cell shape that is thick in the middle and tapered toward the ends.

Fibrous

A threadlike cell shape.

Micrometer ($\mu\text{m}$)

A unit of length equal to one-millionth of a meter or one-thousandth of a millimeter; also called a micron.

Transmission Electron Microscope (TEM)

A microscope that uses beams of electrons to provide high-resolution imaging of internal cell structures.

Scanning Electron Microscope (SEM)

A microscope that produces dramatic 3-D images at high magnification and resolution specifically for surface features.

Cytosol

A clear, viscous, watery colloid within the cell containing enzymes, proteins, amino acids, ATP, electrolytes, dissolved gases, and metabolic wastes; also known as intracellular fluid (ICF).

Cytoskeleton

A network of protein filaments and cylinders that provides structural support, determines cell shape, organizes contents, and directs internal movement.

Microfilaments

Thin cytoskeletal elements ($6\,\text{nm}$ thick) composed of actin protein that form the terminal web.

Intermediate Filaments

Cytoskeletal elements ($8\text{ to }10\,\text{nm}$ thick), made of protein keratin in skin cells, that give the cell shape and resist mechanical stress.

Microtubules

Cytoskeletal cylinders ($25\,\text{nm}$ thick) made of tubulin protofilaments radiating from the centrosome that maintain cell shape, hold organelles, act as tracks for motor proteins, and form axonemes.

Organelles

Internal structures of a cell that carry out specialized metabolic tasks.

Nucleus

The usually largest organelle ($5\,\mu\text{m}$ in diameter) that contains the cell's genetic material.

Nuclear Envelope

The double membrane surrounding the cell nucleus perforated by nuclear pores.

Nuclear Pore Complex

A ring of proteins forming each nuclear pore that regulates molecular traffic through the nuclear envelope and holds its two membrane layers together.

Nuclear Lamina

A web of protein filaments that supports the nuclear envelope.

Nucleolus

A structure within the nucleus where ribosomes are produced.

Rough Endoplasmic Reticulum

A network of parallel, flattened sacs covered with ribosomes continuous with the nuclear envelope that synthesizes membrane phospholipids and proteins.

Smooth Endoplasmic Reticulum

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

Ribosomes

Small granules of protein and RNA that read messenger RNA and synthesize proteins specified by the genetic code.

Golgi Complex

A system of membranous cisterns that synthesizes carbohydrates and modifies, sorts, splices, and packages newly synthesized proteins into vesicles.

Lysosomes

Membrane-bound packages of hydrolytic enzymes responsible for intracellular digestion of nucleic acids, proteins, and complex carbohydrates, as well as autophagy and autolysis.

Autophagy

The intracellular digestion of a cell's surplus organelles.

Autolysis

The digestion of a surplus cell by its own hydrolytic enzymes ('cell suicide').

Peroxisomes

Organelles produced by the endoplasmic reticulum containing enzymes that use molecular oxygen to oxidize organic molecules, producing hydrogen peroxide ($H_2O_2$) to neutralize toxins and break down fatty acids.

Proteasomes

Hollow, cylindrical organelles that dispose of targeted, tagged damaged proteins by breaking them into short peptides and amino acids.

Mitochondria

Double-membraned organelles specialized for extracting energy from organic molecules and transferring it to ATP ('powerhouses' of the cell).

Cristae

Folds in the inner membrane of a mitochondrion.

Centriole

A short cylindrical assembly of microtubules arranged in nine groups of three microtubules each, functioning in cell division and forming basal bodies of cilia and flagella.

Extracellular Fluid (ECF)

Any fluid located outside of cells, including tissue (interstitial) fluid, blood plasma, lymph, and cerebrospinal fluid.

Glycocalyx

A carbohydrate coating on the cell surface formed by glycolipids and glycoproteins that functions in protection, immunity, defense against cancer, cell adhesion, and recognition.

Transmembrane Proteins

Proteins that pass completely through the lipid bilayer of the plasma membrane, possessing both hydrophilic and hydrophobic regions.

Peripheral Proteins

Proteins that adhere to one face of the plasma membrane without penetrating the lipid bilayer, typically tethered to transmembrane proteins and the cytoskeleton.

Ligand-Gated Channels

Gated channel proteins that open or close in response to chemical messengers.

Voltage-Gated Channels

Gated channel proteins that open or close in response to changes in electrical charge across the membrane.

Mechanically Gated Channels

Gated channel proteins that open or close in response to physical stress on the cell.

Second Messenger

An intracellular chemical signal, such as cyclic AMP ($cAMP$), produced inside a cell when a first messenger binds to a surface receptor and activates a G protein.

G Protein

An intracellular peripheral protein that gets energy from guanosine triphosphate (GTP) and relays signals from membrane receptors to enzymes such as adenylate cyclase.

Microvilli

Short membrane extensions ($1\text{ to }2\,\mu\text{m}$) that serve to increase surface area for cell absorption.

Brush Border

A dense, fringe-like layer of microvilli present on the surface of absorptive cells.

Cilia

Hair-like processes ($7\text{ to }10\,\mu\text{m}$ long) that act as sensory antennae or move materials across cell surfaces in coordinated waves using power and recovery strokes.

Cystic Fibrosis

A hereditary disease in which cells fail to install chloride pumps in the plasma membrane, leading to an inadequate saline layer, thick mucus plugging respiratory and pancreatic ducts, and chronic infections.

Pseudopods

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

Filtration

A passive transport process in which physical pressure forces water and small solutes through a selectively permeable membrane or intercellular clefts.

Simple Diffusion

The net movement of particles down their concentration gradient from an area of higher concentration to lower concentration due to spontaneous molecular motion.

Osmosis

The net flow of water through a selectively permeable membrane toward an area of higher solute (lower water) concentration.

Aquaporins

Transmembrane channel proteins specialized to accelerate the passage of water through the plasma membrane during osmosis.

Osmotic Pressure

The hydrostatic pressure required to stop the process of osmosis across a membrane.

Osmolarity

The quantity or total concentration of nonpermeating solutes per liter of solution.

Tonicity

The ability of a surrounding solution to affect cell fluid volume and pressure based on its concentration of nonpermeating solutes.

Hypotonic Solution

A solution with a lower concentration of nonpermeating solutes than intracellular fluid, causing cells to absorb water, swell, and potentially lyse.

Hypertonic Solution

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

Isotonic Solution

A solution whose nonpermeating solute concentration is equal to that of the intracellular fluid, causing no net movement of water or change in cell volume.

Transport Maximum ($T_m$)

The upper limit on the rate of carrier-mediated transport reached when all membrane carrier proteins are saturated with solute.

Uniport

A carrier protein that moves only one type of solute across a membrane.

Symport

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

Antiport

A carrier protein that moves two or more solutes in opposite directions across a membrane (countertransport).

Facilitated Diffusion

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

Primary Active Transport

Carrier-mediated transport moving a solute up its concentration gradient across a membrane through direct consumption of ATP.

Secondary Active Transport

Carrier-mediated transport moving a solute up its concentration gradient without direct ATP consumption, relying on energy gradients created by primary active transport pumps.

Sodium–Potassium Pump ($\text{Na}^+-\text{K}^+$ ATPase)

A primary active transport antiport protein that hydrolyzes one ATP molecule to pump 3 $\text{Na}^+$ ions out of the cell and 2 $\text{K}^+$ ions into the cell.

Phagocytosis

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

Pinocytosis

A form of endocytosis in which a cell takes in droplets of extracellular fluid containing dissolved molecules ('cell drinking').

Receptor-Mediated Endocytosis

A selective form of endocytosis in which specific extracellular molecules bind to receptors on the plasma membrane, causing it to sink inward and form a clathrin-coated vesicle.

Transcytosis

The transport of material across a cell by capturing it via endocytosis on one side and releasing it via exocytosis on the opposite side.

Exocytosis

A vesicular process in which a secretory vesicle fuses with the plasma membrane to release its contents outside the cell.