Prokaryotic vs. Eukaryotic Cells – Key Vocabulary

A comprehensive set of vocabulary flashcards covering the major structures, functions, and distinguishing features of prokaryotic and eukaryotic cells as presented in the lecture notes.

Prokaryote

A simple, unicellular organism lacking a true nucleus and membrane-bound organelles; includes bacteria and archaea.

Eukaryote

A cell or organism with a true, membrane-bound nucleus and membrane-bound organelles; may be unicellular or multicellular.

Nucleus

Membrane-bound control center of eukaryotic cells that houses linear DNA and regulates all cellular activities.

Nucleoid

DNA-containing region in a prokaryotic cell where circular genetic material is located without a surrounding membrane.

Membrane-bound Organelle

Specialized cellular compartment enclosed by a lipid bilayer (e.g., mitochondria, ER, Golgi) found in eukaryotes but absent in prokaryotes.

Plasma Membrane

Phospholipid bilayer that regulates the movement of substances into and out of all cells.

Cell Wall (Bacteria)

Rigid layer outside the plasma membrane that protects bacterial cells and maintains their shape.

Capsule

Sticky outermost layer of some bacteria that aids attachment, defense, and nutrient storage.

Fimbriae

Short, hairlike projections on bacteria that help them adhere to surfaces and to each other.

Pilus (Pili)

Longer bacterial appendage used for attachment; sex pili facilitate DNA transfer during conjugation.

Flagellum

Whip-like bacterial (or eukaryotic) structure that propels the cell toward or away from stimuli.

Plasmid

Small, circular, independently replicating DNA molecule in bacteria carrying extra genes.

Cytoplasm

Gel-like interior of cells where metabolic reactions occur and organelles (or ribosomes) are suspended.

Ribosome

Protein-synthesizing machine found in both prokaryotic and eukaryotic cells; only organelle in prokaryotes.

Inclusion (Bacterial)

Cytoplasmic storage body that reserves nutrients such as glycogen or polyphosphate.

Cytoskeleton

Network of protein filaments (microtubules, microfilaments, intermediate filaments) providing eukaryotic cells with shape, support, and movement.

Circular DNA

Closed-loop genetic material characteristic of prokaryotes and plasmids.

Linear DNA

Strand-like chromosomes found inside the nucleus of eukaryotic cells.

Cocci

Spherical or round bacterial shape.

Bacillus

Rod-shaped bacterial cell type.

Spirilla

Spiral or helical-shaped bacterial cells.

Endosymbiosis

Theory that certain organelles (e.g., mitochondria, chloroplasts) originated from prokaryotes living inside ancestral eukaryotic cells.

Panspermia

Hypothesis that life on Earth began with microorganisms or spores arriving via comets or meteoroids.

Unicellular

Composed of a single cell performing all life functions.

Multicellular

Composed of many specialized, interdependent cells forming tissues and organs.

Colony (Mucilaginous Sheath)

Group of prokaryotic cells embedded in a gelatinous matrix living together without forming true tissues.

Filamentous

Prokaryotic lifestyle in which cells form long chains (filaments).

Photosynthetic Prokaryote

Bacterium that uses sunlight to produce energy—often cyanobacteria.

Decomposer Prokaryote

Bacterium that obtains energy by breaking down dead organic matter.

Disease-Causing Prokaryote

Pathogenic bacterium that feeds on living hosts, causing illness.

Mitochondrion

Eukaryotic organelle where aerobic respiration produces ATP; called the “powerhouse of the cell.”

ATP (Adenosine Triphosphate)

Primary energy currency of the cell produced mainly in mitochondria.

Endoplasmic Reticulum (ER)

Membrane system; Rough ER has ribosomes and synthesizes proteins, Smooth ER lacks ribosomes and makes lipids/detoxifies.

Golgi Complex

Stacks of membranes that modify, sort, and package proteins and lipids for transport.

Lysosome

Animal-cell organelle containing hydrolytic enzymes that digest waste and recycle cellular components.

Centrioles

Paired cylindrical structures that organize the mitotic spindle during animal cell division.

Cell Wall (Plant)

Rigid cellulose layer providing support, protection, and shape to plant cells.

Vacuole (Central)

Large, fluid-filled sac in plant cells for storage and maintaining turgor pressure.

Chloroplast

Green, double-membraned plant organelle where photosynthesis converts light energy into chemical energy.

Chromosome

DNA molecule with associated proteins carrying genetic information; linear in eukaryotes, circular in prokaryotes.

Phospholipid Bilayer

Structural basis of all cellular membranes consisting of hydrophilic heads and hydrophobic tails.