Chapter 3 – Cell Structure and Function (Vocabulary)

A comprehensive set of vocabulary flashcards covering major structures, concepts, and organelles discussed in Chapter 3: Cell Structure and Function.

Cell

Basic unit of life where all biochemical reactions occur; building block of all organisms.

Cell Theory

States that all living things are composed of cells, the cell is the basic unit of life, and all cells arise from pre-existing cells.

Light Microscope

Optical instrument that uses visible light to magnify specimens up to ~400–1000×.

Dissecting Microscope

Low-magnification (≤100×) light microscope used to view larger, three-dimensional specimens such as tissues.

Electron Microscope

Microscope that uses electron beams to achieve magnifications up to ~10,000,000× for ultrastructural study.

Prokaryotic Cell

Small (≈10× smaller), nucleus-lacking cell type found in bacteria; DNA is free in the cytoplasm.

Eukaryotic Cell

Cell type (animals, plants, fungi, protists) possessing a nucleus and membrane-bound organelles.

Plasma Membrane

Phospholipid bilayer with proteins, cholesterol, and carbohydrates that regulates selective passage into and out of the cell.

Phospholipid Bilayer

Double layer of amphipathic lipids forming the structural foundation of cellular membranes.

Fluid Mosaic Model

Concept describing the plasma membrane as a dynamic, fluid composition of lipids, proteins, and carbohydrates in constant motion.

Cytoplasm

Region between the plasma membrane and nucleus containing cytosol and organelles.

Nucleus

Membrane-bound organelle that houses DNA, nucleolus, and controls cellular activities.

Nuclear Envelope

Double-membrane structure surrounding the nucleus, continuous with rough ER.

Nuclear Pore

Protein-lined channel in the nuclear envelope permitting selective exchange of materials.

Nucleolus

Dense nuclear region where ribosomal RNA (rRNA) synthesis and ribosome assembly occur.

Chromatin

Complex of DNA and proteins found in the nucleus; condenses to form chromosomes during division.

Ribosome

Non-membranous organelle made of rRNA and proteins; site of protein synthesis (free or bound to RER).

Endoplasmic Reticulum (ER)

Extensive membranous network continuous with nuclear envelope; subdivided into RER and SER.

Rough ER (RER)

ER region studded with ribosomes; modifies and folds newly synthesized proteins.

Smooth ER (SER)

Tubular ER without ribosomes; synthesizes lipids, steroid hormones, carbohydrates and stores Ca²⁺.

Golgi Apparatus

Stack of flattened sacs (cis and trans faces) that modifies, packages, and ships proteins and lipids.

Lysosome

Acidic, enzyme-filled vesicle acting as the cell’s “garbage disposal” for worn organelles and pathogens.

Endomembrane System

Interconnected membranes (nuclear envelope, ER, Golgi, lysosomes, plasma membrane) that synthesize, modify, and transport proteins/lipids.

Mitochondrion

Double-membranous “powerhouse” producing ATP; contains cristae and matrix.

ATP (Adenosine Triphosphate)

Primary cellular energy currency generated mainly by mitochondria.

Cristae

Folded inner mitochondrial membrane surfaces increasing area for ATP-producing reactions.

Chloroplast

Photosynthetic organelle in plants with double membrane, stroma, and internal thylakoid stacks (grana).

Thylakoid

Flattened membrane sac inside chloroplast where light-dependent photosynthesis occurs.

Stroma

Fluid interior of chloroplast surrounding thylakoids; site of Calvin cycle reactions.

Grana

Stacks of thylakoids within a chloroplast.

Endosymbiosis

Evolutionary theory that mitochondria and chloroplasts originated as free-living bacteria engulfed by ancestral cells.

Cytoskeleton

Network of protein fibers (microtubules, intermediate filaments, microfilaments) that maintains cell shape and facilitates movement.

Microtubule

Tubulin-based cytoskeletal filament involved in organelle transport, mitotic spindle, cilia, and flagella motion.

Intermediate Filament

Durable cytoskeletal fiber (e.g., keratin) providing mechanical strength and shape stability.

Microfilament

Actin-based filament enabling cell motility, muscle contraction, and cytokinesis cleavage furrow.

Cilium (plural Cilia)

Short, numerous, hair-like projections that move cells or sweep substances across cell surfaces.

Flagellum

Long, whip-like projection (one or few per cell) that propels cells such as sperm or some bacteria.

Extracellular Matrix (ECM)

Meshwork of collagen and glycoproteins outside animal cells providing support and signaling.

Cell Wall

Rigid carbohydrate-rich layer (e.g., pectin, cellulose) outside the plasma membrane of plant cells for protection and support.

Tight Junction

Seal between adjacent animal cells preventing leakage of fluids between them.

Desmosome

Spot-weld type junction anchoring adjacent animal cells, common in skin and muscle.

Gap Junction

Intercellular channel in animal cells allowing direct cytoplasmic exchange of ions and molecules.

Plasmodesma (plural Plasmodesmata)

Cytoplasmic channel through plant cell walls permitting transport and communication between cells.

Vesicle

Small, membrane-bound sac used for transport and storage within cells.

Vacuole

Large vesicle prominent in plant cells, involved in storage, turgor maintenance, and waste breakdown.