General Biology – Cell Theory & Cell Structure

50 vocabulary flashcards covering key figures, principles, structures, and tissues related to cell theory and cell biology.

Cell

The smallest structural, functional, and biological unit of life; capable of independent replication and called the building block of life.

Cell Theory

Universally accepted concept that all living organisms are composed of cells, cells are the basic units of structure and function, and all cells arise from pre-existing cells.

Robert Hooke

17th-century scientist who coined the term “cells” after observing cork with an early compound microscope.

Anton van Leeuwenhoek

Dutch lens-maker who first described living microorganisms (“animalcules”) such as bacteria and protozoa.

Robert Brown

Scottish botanist who discovered and named the cell nucleus and reported Brownian motion.

Felix Dujardin

French biologist who identified the living cell substance he called sarcode, later termed protoplasm.

Matthias Jakob Schleiden

German botanist who concluded that all plants are composed of cells; co-founder of classical cell theory.

Theodor Schwann

German physiologist who extended cell theory to animals, establishing that all animals are made of cells.

Henri Joachim Dutrochet

French physiologist who proposed that the cell is both the structural and physiological unit of life.

Robert Remak

Polish scientist who provided evidence that new animal cells arise by binary fission of pre-existing cells.

Rudolf Virchow

Father of Modern Pathology; stated that new cells come from existing cells, summarised as “Omnis cellula e cellula.”

"Omnis cellula e cellula"

Latin phrase coined by Virchow meaning “Every cell stems from another cell,” central to cell theory.

Three Tenets of Classical Cell Theory

1) All organisms consist of one or more cells; 2) The cell is the basic unit of structure and organization; 3) Cells arise from pre-existing cells.

Modern Cell Theory

Adds that cells carry hereditary information, share common chemical composition, and form by division to create trillions of cells in complex organisms.

Prokaryotic Cell

Cell type lacking a nucleus; genetic material is dispersed in the cytoplasm (e.g., bacteria).

Eukaryotic Cell

Cell type with a membrane-bound nucleus; includes plant, animal, fungal, and protist cells.

Cell Membrane (Plasma Membrane)

Lipid bilayer with proteins that encloses the cell, controls substance passage, and mediates cell recognition.

Cytoplasm

Fluid interior of a cell containing cytoskeleton, organelles, and dissolved substances; often called the cell’s “soup.”

Nucleus

Largest membrane-bound organelle in eukaryotes; houses DNA and controls transcription and replication.

Nuclear Envelope

Double membrane that separates the nucleus from the cytoplasm and regulates nuclear transport.

Nucleoplasm

Semi-fluid medium inside the nucleus that suspends nucleolus and chromatin.

Nucleolus

Dense structure within the nucleus where ribosome subunits are produced (ribosome biogenesis site).

Chromosome

DNA-protein complex that packages genetic material and carries hereditary information.

Ribosome

Particle composed of rRNA and protein that serves as the site of protein synthesis; free or bound to rough ER.

Endoplasmic Reticulum (ER)

Network of membranous sacs and tubes continuous with the nuclear envelope; transports and synthesizes materials.

Rough ER

ER studded with ribosomes; synthesizes and modifies proteins destined for membranes or secretion.

Smooth ER

ER lacking ribosomes; specializes in lipid synthesis, carbohydrate metabolism, and detoxification.

Golgi Apparatus

Stack of flattened cisternae that modifies, sorts, and packages proteins and lipids into vesicles for distribution.

Mitochondrion

Powerhouse organelle generating ATP through cellular respiration; inner folds are called cristae.

Vacuole

Membrane-bound sac for storage, digestion, waste disposal, and turgor maintenance; large in plant cells.

Lysosome

Enzyme-filled vesicle that digests macromolecules and cellular debris; the cell’s “garbage disposal.”

Peroxisome

Organelle containing enzymes that break down fatty acids and detoxify harmful substances.

Cytoskeleton

Network of protein filaments (microtubules, microfilaments, intermediate filaments) that supports shape and enables movement.

Microtubule

Hollow tube of tubulin providing structural support, intracellular transport tracks, and spindle fibers.

Microfilament

Thin actin filament involved in cell shape, muscle contraction, and pseudopod movement.

Intermediate Filament

Rope-like filament providing tensile strength and anchoring organelles within the cell.

Plastid

Plant organelle containing DNA; includes chloroplasts, chromoplasts, and leucoplasts for pigment and storage.

Chloroplast

Green plastid containing chlorophyll; site of photosynthesis in plants and some protists.

Chromoplast

Plastid with red, orange, or yellow pigments that give color to fruits and flowers.

Leucoplast

Colorless plastid specialized for starch, lipid, or protein storage in non-photosynthetic tissues.

Centrosome

Microtubule-organizing center that regulates the cell division cycle in eukaryotes.

Centriole

Cylindrical tubulin structure; a pair within the centrosome helps organize spindle fibers during mitosis.

Epithelial Tissue

Cell layers covering body surfaces and cavities; functions in protection, absorption, secretion, and sensation.

Connective Tissue

Diverse tissue type that binds, supports, and cushions body structures (e.g., bone, cartilage, adipose).

Muscle Tissue

Tissue composed of contractile cells enabling movement; includes skeletal, cardiac, and smooth muscle.

Nervous Tissue

Tissue specialized for rapid communication via electrical impulses; composed of neurons and neuroglia.

Neuron

Conducting cell of nervous tissue capable of irritability and conductivity; consists of soma, dendrites, and axon.

Neuroglia

Supportive nervous tissue cells that nourish neurons and form protective barriers against toxins.

Irritability (Neuron Property)

Ability of a neuron to respond to stimuli, initiating an electrical impulse.

Axon

Single long nerve fiber that conducts impulses away from the neuron’s cell body toward other cells.