Cell Theory, History, and Microscopy – Lecture Vocabulary

These vocabulary flashcards cover essential terms and scientists related to cell theory, cell history, microscopy, and basic cell biology from the lecture notes.

Cell

The basic structural and functional unit of life; all living organisms are composed of one or more cells.

Classic Cell Theory

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

Modern Cell Theory

Expands on the classic theory by adding that (1) cells carry genetic material passed from generation to generation and (2) all cells share the same chemical composition.

Microscope

An optical instrument that produces a magnified image of objects too small to be seen with the naked eye.

Light Microscope

A type of microscope that uses visible light and lenses to magnify cell structures, allowing observation of specimens 0.001–0.1 mm in size.

Eyepiece (Ocular Lens)

The lens at the top of a light microscope through which a user looks to see the magnified image.

Objective Lenses

Replaceable lenses of varying magnifications located on the revolving nosepiece of a microscope.

Revolving Nosepiece

Rotating part of a microscope that holds and switches the objective lenses.

Stage

The flat platform on a microscope where the specimen slide is placed.

Aperture

The opening in the microscope stage that allows light to pass through the specimen.

Mirror/Light Source

Illuminates the specimen by reflecting or emitting light upward through the aperture.

Coarse Adjustment Wheel

Large focusing knob on a microscope that moves the stage or objective lens quickly to bring a specimen into general focus.

Fine Adjustment Wheel

Small focusing knob used to make fine, precise changes to focus after using the coarse adjustment.

Cytology

The branch of biology that studies the structure and function of cells.

Nerve Cell (Neuron)

Star-shaped cell of the nervous system with dendrites and a long axon; transmits information to and from the brain.

Red Blood Cell (Erythrocyte)

Oval, biconcave cell lacking a nucleus; rich in hemoglobin for oxygen transport in the bloodstream.

Cell Membrane

The boundary that surrounds a cell, regulating entry and exit of substances while maintaining chemical composition.

Cytoplasm

Gel-like substance inside the cell membrane that contains organelles and is the site of many metabolic activities.

Protoplasm

The living content of a cell—including cytoplasm and nucleus—first called “sarcode” by Felix Dujardin.

Nucleus

Membrane-bound organelle discovered by Robert Brown in 1831; houses genetic material (DNA).

Zacharias Janssen

Dutch spectacle-maker credited with creating the first compound microscope around 1590.

Robert Hooke

English scientist who coined the term “cell” in 1665 after observing cork under a microscope.

Anton van Leeuwenhoek

Dutch naturalist regarded as the Father of Microscopy; first observed living cells he called “animalcules.”

Robert Brown

Scottish botanist who discovered and named the nucleus in plant cells in 1831.

Felix Dujardin

French biologist who, in 1835, introduced the term “protoplasm” for the living material of cells.

Matthias Schleiden

German botanist who concluded in 1838 that all plants are composed of cells.

Theodor Schwann

German zoologist who declared in 1839 that all animals are composed of cells, helping establish cell theory.

Rudolf Virchow

German physician who, in 1858, stated “omnis cellula e cellula” (all cells come from cells).

Metabolic Activities

Chemical reactions occurring within cells that sustain life, such as energy production and synthesis of molecules.

Genetic Material

DNA contained in cells that carries hereditary information transmitted from generation to generation.

Unicellular Organism

An organism, e.g., Euglena, consisting of a single cell performing all life functions.

Multicellular Organism

An organism, such as a human, composed of many specialized cells working together.

Cell Division

Process by which a parent cell divides to form two (or more) daughter cells, enabling growth and reproduction.

Hemoglobin

Iron-containing protein in red blood cells responsible for binding and transporting oxygen.

Axon

Long, single projection of a neuron that transmits electrical impulses away from the cell body.

Dendrite

Short, branched extensions of a neuron that receive signals from other cells.