Eukaryotic Cell – Vocabulary Review

A comprehensive set of vocabulary flashcards covering the major structures, processes, and theories discussed in the lecture on eukaryotic cells.

Eukaryotic Cell

A cell whose DNA is enclosed within a nucleus and contains membrane-bound organelles.

Plasma Membrane

Phospholipid bilayer with embedded proteins that acts as a selectively permeable barrier controlling entry and exit of materials.

Cell Wall

Rigid outer layer (in plants, fungi, some protists) that provides strength, rigidity, and protection against osmotic pressure.

Cellulose

Structural polysaccharide that forms the primary component of plant cell walls.

Chitin

Nitrogen-containing polysaccharide that forms the main component of fungal cell walls.

Flagellum

Long, whip-like appendage used for locomotion; moves in a wave-like motion in eukaryotes.

Cilium

Short, hair-like projection that beats in coordinated waves to move a cell or substances across its surface.

Nucleus

Membrane-bound control center of the cell that houses linear chromosomes (DNA).

Nuclear Envelope

Double membrane surrounding the nucleus, continuous with the ER, containing nuclear pores.

Nuclear Pore

Protein-lined opening in the nuclear envelope that regulates traffic between nucleus and cytoplasm.

Nucleolus

Dense region inside the nucleus where rRNA is synthesized and ribosomal subunits assemble.

Chromatin

DNA-protein complex in the nucleus; condenses into chromosomes during cell division.

Ribosome

rRNA-protein complex (80S in eukaryotes) that translates mRNA into polypeptides; not membrane-bound.

Endomembrane System

Interconnected membrane network including nuclear envelope, ER, Golgi, lysosomes, vesicles, and plasma membrane.

Endoplasmic Reticulum (ER)

Extensive membrane channels continuous with the nuclear envelope; involved in synthesis and transport.

Rough ER

ER studded with ribosomes; site of synthesis and initial transport of secreted and membrane proteins.

Smooth ER

ER lacking ribosomes; synthesizes steroids, stores Ca²⁺, detoxifies, and forms transport vesicles.

Golgi Apparatus

Stack of flattened sacs that modifies, sorts, and packages proteins and lipids for transport.

Vesicle

Small membrane-bounded sac used to transport substances within or outside the cell.

Lysosome

Acidic, enzyme-filled vesicle that carries out hydrolysis to digest and recycle cellular material.

Peroxisome

Microbody containing oxidative enzymes (e.g., catalase) that break down fatty acids and detoxify H₂O₂.

Catalase

Peroxisomal enzyme that converts toxic hydrogen peroxide into water and oxygen.

Microbody

Generic term for small, enzyme-containing vesicles such as peroxisomes.

Vacuole

Membrane sac of fluid; small and numerous in animals, large central tonoplast in plants for storage and turgor.

Tonoplast

The membrane surrounding the central vacuole in plant cells.

Endocytosis

Active uptake of external materials by invagination of the plasma membrane to form a vacuole.

Phagocytosis

‘Cell eating’; endocytic engulfment of large particles or cells.

Pinocytosis

‘Cell drinking’; endocytic uptake of extracellular fluid and dissolved solutes.

Exocytosis

Process of releasing cellular contents to the exterior via fusion of a vesicle with the plasma membrane.

Mitochondrion

Double-membraned organelle that performs aerobic respiration and produces ATP; the cell’s ‘powerhouse.’

Adenosine Triphosphate (ATP)

High-energy molecule produced mainly in mitochondria; universal energy currency of the cell.

Chloroplast

Plant plastid where photosynthesis converts light energy into glucose and ultimately ATP.

Thylakoid

Flattened membrane sac inside chloroplasts that contains photosynthetic pigments such as chlorophyll.

Leucoplast

Colorless plastid in plants specialized for storage, primarily of starch.

Endosymbiotic Theory

Hypothesis that mitochondria and chloroplasts originated as free-living bacteria engulfed by ancestral eukaryotic cells.

70S Ribosome

Smaller ribosome type found in prokaryotes and in mitochondria/chloroplasts, supporting endosymbiosis.

Cytosol

Aqueous fluid portion of the cytoplasm containing dissolved nutrients and ions.

Cytoplasm

All cellular contents between the nucleus and plasma membrane; includes cytosol and organelles.

Cytoskeleton

Network of protein fibers (microtubules, actin filaments, intermediate filaments) providing structure and facilitating movement.

Microtubule

Hollow tubulin filament involved in cell shape, organelle movement, and chromosome separation.

Actin Filament (Microfilament)

Thin filament composed of actin; supports cell shape and aids in movement and cytokinesis.

Intermediate Filament

Stable, rope-like filament providing tensile strength and mechanical stability to cells.

Centriole

Cylindrical structure of microtubules that organizes spindle fibers during animal cell division.

Selective Permeability

Property of membranes to allow some substances to cross more easily than others.