Lab 5 – The Cell: Key Vocabulary

A vocabulary set covering major structures, principles, and classifications from the Lab 5 lecture on cells.

Cell Theory

States that all living things are made of one or more cells, the cell is the smallest unit of life, and all cells arise from pre-existing cells.

Plasma Membrane

Phospholipid bilayer that encloses the cell and maintains a stable internal environment.

DNA (Deoxyribonucleic Acid)

Large molecule carrying genetic instructions for building cell components and functions.

Cytoplasm

Semifluid matrix inside the cell containing chemicals, proteins, ribosomes, vesicles, nutrients, and waste.

Prokaryotic Cell

Small, single-celled organism lacking a nucleus and membrane-bound organelles (Domains Archaea and Bacteria).

Eukaryotic Cell

Larger cell with a nucleus and many membrane-bound organelles (Domain Eukarya).

Nucleoid Region

Area in a prokaryote where circular DNA is located; not membrane-bound.

Domain Archaea

One of the two prokaryotic domains; includes extremophiles with unique enzymes.

Domain Bacteria

Prokaryotic domain containing species such as Escherichia coli; diverse metabolic abilities.

Domain Eukarya

Domain of organisms with eukaryotic cells; divided into Protista, Plantae, Fungi, and Animalia.

Organelle

Membrane-bound structure within eukaryotic cells performing specialized functions.

Nuclear Envelope

Double membrane surrounding the nucleus, containing protein-lined pores for transport.

Chromatin

Complex of DNA and associated proteins found within the nucleus.

Nucleolus

Dense nuclear region where ribosomal RNA is synthesized and ribosome subunits assemble.

Rough Endoplasmic Reticulum

ER studded with ribosomes; synthesizes secretory and membrane proteins.

Smooth Endoplasmic Reticulum

ER lacking ribosomes; synthesizes lipids and detoxifies chemicals.

Golgi Apparatus

Stack of flattened membranes that modifies, sorts, and packages proteins and lipids.

Lysosome

Acidic vesicle containing hydrolytic enzymes for digesting food and waste.

Peroxisome

Organelle that metabolizes wastes and neutralizes toxic peroxides.

Vacuole

Membrane-bound sac for storage; large central vacuole in plants maintains turgor pressure.

Cytoskeleton

Network of protein fibers providing structure, transport, and movement within cells.

Microtubule

Hollow cytoskeletal filament forming mitotic spindle and maintaining cell shape.

Microfilament

Thin actin filament forming the cellular cortex and aiding in movement.

Intermediate Filament

Fibrous protein filament providing mechanical stability and anchoring organelles.

Centrosome

Microtubule-organizing center in animal cells; contains a pair of centrioles.

Mitochondrion

Organelle that produces ATP through cellular respiration; “powerhouse” of the cell.

Cell Wall

Rigid structure outside the plasma membrane of plants, fungi, and many prokaryotes; maintains shape.

Plasmodesmata

Cytoplasmic channels that connect adjacent plant cells for communication and transport.

Chloroplast

Plant organelle containing chlorophyll; site of photosynthesis.

Capsule (Bacterial)

Sticky outer layer enabling bacteria to attach to surfaces and evade host defenses.

Flagellum

Long whip-like appendage used by some bacteria for motility.

Fimbriae

Short hair-like projections that help bacteria adhere to surfaces.

Pilus (Plural: Pili)

Longer protein appendage in bacteria; involved in attachment and DNA transfer.

Bacillus (Bacilli)

Rod-shaped bacterial cell form.

Coccus (Cocci)

Spherical bacterial cell form.

Spirochaete

Spiral-shaped bacterial cell form.

Protista

Kingdom of mostly single-celled eukaryotes such as algae and protozoa.

Fungi

Kingdom of eukaryotic organisms including molds, yeasts, and mushrooms; cell walls contain chitin.

Animalia

Kingdom of multicellular eukaryotes that lack cell walls and obtain nutrients by ingestion.