BGY 3002: Cell Biology - History, Techniques, and Cell Properties

Vocabulary flashcards covering the history of cell biology, microscopy techniques, comparative properties of prokaryotic and eukaryotic cells, extremophiles, viruses, viroids, and prions.

Cell Theory

The foundational biological theory stating that all organisms consist of one or more cells, the cell is the basic unit of structure for all organisms, and cells can arise only by division from a preexisting cell.

Cellulae

The Latin term used by Robert Hooke in approximately 1600 to describe the honeycomb-like network of empty compartments observed in a thin slice of cork under a compound microscope.

Leeuwenhoek's Microscope

A single-lens microscope featuring a biconvex lens mounted between two metal plates, capable of magnifying objects approximately 270 times with a resolution of approximately $1.35\,\mu\text{m}$, used to first observe bacteria and other microorganisms.

Robert Brown

The Scottish botanist who discovered in the 1830s that every plant cell contains a rounded internal structure called the nucleus.

Rudolf Virchow

The scientist who formulated the third tenet of the cell theory 20 years after Schwann and Schleiden: that cells can arise only by division from a preexisting cell.

Microtome

An instrument in cytology that enables the rapid and efficient preparation of thin tissue slices of uniform thickness for microscopic observation.

Phase Contrast Microscopy

A light microscopy technique specifically utilized for observing living cells without the need for fixation or lethal staining.

Electron Microscope

A high-magnification instrument ($100{,}000\times$) with a limit of resolution of $0.1\text{--}0.2\,\text{nm}$, compared to the $200\text{--}350\,\text{nm}$ resolution limit of a standard light microscope.

Ultracentrifugation

A biochemical technique developed by Theodor Svedberg and Albert Claude that uses extremely high rotational speeds to separate subcellular structures and macromolecules based on their size, shape, and density.

Surface Area-to-Volume Limitation

A primary constraint keeping cells microscopic: as a cell increases in size, its exchange surface area becomes limiting relative to its volume, and diffusion distances from the surface to the interior become too large.

Cell Differentiation

The process through which unspecialized embryonic cells receive positional signals from their surrounding environment to develop into specialized cell types (approximately 250 distinct types in a human fetus).

Prokaryotic Ribosome

A $70\text{S}$ ribonucleoprotein complex consisting of 3 RNA molecules and 55 proteins, responsible for protein translation in prokaryotes.

Eukaryotic Ribosome

An $80\text{S}$ ribonucleoprotein complex consisting of 4 RNA molecules and approximately 78 proteins, responsible for translation in eukaryotic cells.

Methanogens

A specialized group of Archaea (archaeabacteria) that convert $\text{CO}_2$ and $\text{H}_2$ gases into methane ($\text{CH}_4$).

Halophiles

Extremophilic Archaea that thrive in hypersaline habitats such as the Dead Sea, enduring salinities up to approximately $5\,\text{M } \text{MgCl}_2$.

Strain 121

A hyperthermophilic archaeon discovered at hydrothermal vents of the ocean floor that is capable of growing and dividing in superheated water at a temperature of $121^\circ\text{C}$.

Mycoplasma

The smallest known living cells (diameter of approximately $0.2\,\mu\text{m}$) and the only group of prokaryotes that entirely lacks a cell wall.

Cyanobacteria

Photosynthetic eubacteria (blue-green algae) capable of nitrogen ($\text{N}_2$) fixation; they contain concentric cytoplasmic membranes similar to plant thylakoids and can live within polar bear hair, imparting a greenish color.

Virion

The intact, inert physical viral particle when it exists outside of a host cell, consisting of a genetic material core enclosed in a protective protein capsid.

Tobacco Mosaic Virus (TMV)

A rod-shaped RNA plant virus measuring approximately $300\,\text{nm}$ long and $18\,\text{nm}$ in diameter, composed of identical protein subunits arranged helically around a single helical RNA molecule.

Bacteriophage

A virus that specifically infects and replicates within bacterial cells, typically featuring a head containing nucleic acid, a protein coat, and tail fibers.

Viroid

An infectious agent smaller than a virus, composed entirely of a circular, single-stranded RNA molecule of 300–400 nucleotides without a protein capsid, exclusively infecting eukaryotes.

Prion

A proteinaceous infective particle devoid of nucleic acids and cellular structure, composed of protein strands capable of causing transmissible neurodegenerative diseases such as scrapie in sheep, BSE in cows, and variant CJD in humans.

HeLa Cells

The first human cells successfully cultured for long periods in vitro; derived from a cervical tumor, these cancerous cells can replicate indefinitely under appropriate conditions.