Cell Theory and Parts of the Cell

Vocabulary flashcards covering key scientists, foundational cell theory concepts, and the structure and function of major cellular organelles.

Microscope

An instrument that magnifies small objects; first built by Zacharias Janssen in the 1590s.

Cell

The basic unit of structure and function in living things; term coined by Robert Hooke.

Zacharias Janssen

Dutch eyeglass maker who invented the first microscope in the 1590s.

Robert Hooke

Scientist who observed cork and introduced the word “cell” in 1665.

Anton van Leeuwenhoek

Father of Microbiology; observed living “animalcules” in pond water in 1674.

Matthias Schleiden

German botanist who declared that all plants are composed of cells (1838).

Theodor Schwann

German physiologist who concluded that all animals are made of cells (1839).

Rudolf Virchow

Proposed that cells arise only from pre-existing cells through cell division (1855).

Cell Theory

States that 1) all living things are made of cells, 2) the cell is the basic unit of life, and 3) cells come from pre-existing cells.

Modern Cell Theory

Adds that cells pass genetic material during division, share similar chemistry, and are the sites of energy flow.

Cell Membrane

Thin phospholipid-protein bilayer that encloses the cell and regulates movement of substances.

Cell Wall

Rigid cellulose-rich layer surrounding plant cells, providing protection, support, and structure.

Nucleus

Membrane-bound organelle that stores DNA and directs cellular activities; the cell’s “brain.”

Nucleolus

Dense region inside the nucleus responsible for producing and assembling ribosomes.

Ribosome

Complex of rRNA and proteins that serves as the site of protein synthesis.

Mitochondrion

Double-membrane organelle with its own DNA that generates cellular energy in the form of ATP; the “powerhouse.”

Endoplasmic Reticulum (ER)

Network of membranous sacs and tubules involved in protein and lipid production and transport.

Rough ER

ER studded with ribosomes; modifies newly made proteins and synthesizes membrane phospholipids.

Smooth ER

ER without ribosomes; synthesizes lipids, carbohydrates, steroids, detoxifies drugs, and stores calcium ions.

Golgi Body

Stack of flattened membranes that sort, tag, package, and distribute proteins and lipids; the cell’s “mailman.”

Lysosome

Membrane-bound sac of digestive enzymes that breaks down waste, damaged organelles, and aids apoptosis; the “garbage collector.”

Chloroplast

Disc-shaped, chlorophyll-containing organelle where photosynthesis occurs in plant cells.

Vacuole

Large fluid-filled sac that maintains water balance, stores substances, and helps keep plant cell shape.

Cytoskeleton

Network of protein filaments (microfilaments, microtubules, intermediate filaments) providing shape, movement, and spindle formation.

Microfilament

Thin actin filament of the cytoskeleton involved in cell movement and structure.

Microtubule

Hollow tubulin filament that forms tracks for organelles and mitotic spindle fibers.

Intermediate Filament

Rope-like cytoskeletal fiber providing tensile strength to cells.

Cytoplasm

Semi-fluid substance inside the cell where organelles are suspended.

ATP

Adenosine triphosphate; energy-carrying molecule produced mainly in mitochondria.

Chlorophyll

Green pigment in chloroplasts that captures light energy for photosynthesis.

Apoptosis

Programmed cell death, often facilitated by lysosomal enzymes.

Cell Division

Process by which a parent cell divides to form daughter cells; foundation of growth and reproduction.

Brain of the Cell

Nickname for the nucleus, reflecting its regulatory role.

Powerhouse of the Cell

Nickname for the mitochondrion because it produces ATP.

Subway System of the Cell

Nickname for the endoplasmic reticulum, which transports molecules within the cell.

Mailman of the Cell

Nickname for the Golgi body because it packages and ships proteins and lipids.

Garbage Collector of the Cell

Nickname for the lysosome due to its role in waste breakdown.

Security Guard of the Cell

Nickname for the cell membrane because it controls entry and exit of substances.

Photosynthesis

Process in chloroplasts that converts light energy, CO₂, and water into glucose and oxygen.

Spontaneous Generation

Disproved belief that life arises from non-living matter; refuted by Virchow’s work and cell theory.