Microscopy, Cell Theory, and Cell Structures

A comprehensive set of vocabulary flashcards covering the history of microscopy, the anatomy of light and electron microscopes, cell theory, prokaryotic vs. eukaryotic structures, and specialized cell modifications.

Hans & Zacharias Janssen (1590s)

Constructed the very first primitive prototype compound microscope by aligning multiple curved glass lenses; magnification of $3\times$ to $9\times$.

Robert Hooke (1665)

Father of Microscopy who published 'Micrographia' and coined the term 'Cell' from the Latin 'cella' after examining dead oak tree cork bark.

Antonie van Leeuwenhoek (1676)

Father of Microbiology who discovered bacteria, protozoans, and sperm cells (termed 'Animalcules') using high-precision single-lens microscopes.

Ernst Ruska (1931)

Built the first functional Electron Microscope prototype, replacing light waves with high-energy electron beams.

Compound Light Microscope

Uses visible light and glass lenses to reach magnification up to $1,000\times$; capable of viewing live, moving cells in liquid states.

Scanning Electron Microscope (SEM)

A type of electron microscope that bounces electrons off surfaces to resolve ultra-sharp, $3\text{D}$ external surfaces.

Transmission Electron Microscope (TEM)

An electron microscope that shoots electrons through sliced cell sections to view internal cross-sections.

Coarse Adjustment Knob

The larger focus gear used for rapid stage movement to find the specimen plane; used with Scanning and Low-Power Objectives.

Fine Adjustment Knob

The smaller gear used for micro-movements to bring fine features into crisp resolution under high power.

Oil Immersion Objective ($100\times$)

Requires specialized high-density cedarwood oil to bridge the gap between lens and slide, trapping light rays for maximum resolution.

Condenser

A curved lens located below the stage that converges raw light into a focused, highly concentrated beam aimed through the specimen.

Iris Diaphragm

An adjustable system beneath the condenser that regulates the volume of light reaching the specimen.

Total Magnification Calculation

Found by multiplying the power of the ocular lens by the power of the selected objective lens ($10\times \text{ Ocular} \times 40\times \text{ HPO} = 400\times$).

Matthias Schleiden & Theodor Schwann

Botanist and zoologist who respectively established the foundation of classical cell theory in $1838$ and $1839$.

Omnis cellula e cellula

A Latin phrase popularized by Rudolf Virchow (1855) meaning 'All cells arise from pre-existing cells,' debunking spontaneous generation.

Surface Area to Volume Ratio

A geometric principle stating that as a cell expands, volume increases by cube while surface area increases by square, limiting cell size for efficiency.

Prokaryotic Cells

Oldest, simplest cells (appearing $3.5$ billion years ago) that lack a nuclear envelope and membrane-bound compartments; belong to Bacteria and Archaea.

Eukaryotic Cells

Advanced cell architectures containing a true double-membrane nucleus and membrane-bound organelles; includes Protists, Fungi, Plants, and Animals.

Nucleoid

The open, non-membrane-bound irregular region in prokaryotes where the single, large, circular main chromosome is located.

Plasmids

Small, independent satellite rings of non-chromosomal $DNA$ in bacteria that carry accessory genes like antibiotic resistance.

Peptidoglycan

A molecule composed of cross-linked sugars and amino acids that forms the rigid cell wall of bacteria.

Fimbriae

Short, numerous, hair-like protein projections on bacteria that function as anchors for attachment to surfaces or host tissues.

Pili (Sex Pili)

Longer, hollow, tube-like protein bridges used during bacterial conjugation to transfer plasmids between cells.

Nucleolus

A hyper-dense region inside the nucleus tasked exclusively with assembling raw ribosomes.

$70\text{S}$ vs. $80\text{S}$ Ribosomes

Prokaryotic ribosomes are smaller ($70\text{S}$) compared to eukaryotic ribosomes ($80\text{S}$), where 'S' stands for Svedberg units.

Smooth Endoplasmic Reticulum (SER)

A membrane network that manufactures lipids, processes carbohydrates, and filters toxins; found in high concentrations in human liver cells.

Golgi Apparatus

A fulfillment warehouse named after Camillo Golgi that adds carbohydrate 'tags' (forming glycoproteins) and packages cargo into shipping vesicles.

Apoptosis

Programmed cell death occurring when internal lysosomes break open simultaneously to digest a damaged cell from the inside out.

Endosymbiotic Theory

The theory that mitochondria were once free-living, oxygen-breathing prokaryotes swallowed by an ancestral cell in a survival partnership.

Fluid Mosaic Model (1972)

The modern membrane model by Singer-Nicolson describing the membrane as a dynamic, shifting sheet of phospholipids and irregular protein patterns.

Microvilli

Microscopic, non-motile membrane folds on epithelial cells that expand surface area to optimize absorption.

Gap Junctions / Plasmodesmata

Direct protein tunnels linking neighboring cells (Gap Junctions in animals, Plasmodesmata in plants) for instant molecular and signal flow.

Erythrocytes (Red Blood Cells)

Modified biconcave discs that lack a nucleus and mitochondria to maximize space for hemoglobin and prevent consumption of transported oxygen.