General Cytology, Histology, and Cell Biology Vocabulary

Comprehensive vocabulary flashcards generated from the general cytology, histology, microscopy, and cell biology lecture notes.

Cytology

The interrogation and study of the structure and function of cells.

Histology

The study of the tissues of the body and how these tissues are arranged to constitute organs.

Embryology

The study of fetal developments at a cellular level and the development of an embryo.

Extracellular Matrix (ECM)

Interacting tissue component composed of macromolecules (such as collagen fibrils) that span cells to provide support in transporting nutrients and waste.

Cell Theory

Theory postulated in 1839 by Schleiden and Schwann dictating that life exists only in the form of cells, all organisms consist of cells as the basic unit of function, each cell derives from another cell, and cell structure and function share a mutual connection.

Fluorescence Microscopy

Microscopy technique where cells dyed with fluorescent compounds are irradiated with UV light, emitting light of a longer wavelength to visualize specific cellular components.

Phase-Contrast Microscopy

Microscopy technique that measures the time taken for light to pass through an object, allowing visualization of living cells without requiring dyes.

Transmission Electron Microscopy (TEM)

Microscopy method passing electrons emitted from a metallic filament cathode through thin tissue sections, providing resolution around $3\,nm$ and magnification up to 120,000 times.

Scanning Electron Microscopy (SEM)

Microscopy method where surface-reflected electrons from a dried, heavy metal-coated (often gold) specimen produce 3D black and white images on a monitor.

Fixation

The initial step in slide preparation involving immersion of a sample in a stabilizing compound (e.g., Formaldehyde) to preserve cells and prevent enzyme digestion.

Histochemistry

Branch of science concerned with the identification and distribution of the chemical constituents of tissues by means of stains, indicators, and microscopy.

Periodic Acid-Schiff (PAS) Reaction

Histochemical reaction used to demonstrate carbohydrates/polysaccharides by breaking bonds between adjacent carbons using periodic acid, allowing Schiff reagent to yield a purple color.

Feulgen Reaction

Histochemical staining technique specifically used to identify DNA, producing a red color.

Immunohistochemistry

Process utilizing polyclonal or monoclonal antibodies tagged with chromogenic or fluorescent markers to identify specific antigens in tissues, commonly used in tumor diagnosis.

Cell Fractionation

Process of separating cellular components through homogenization, filtration, and differential centrifugation based on density to isolate organelles while preserving their functions.

Autoradiography

Technique using radioactively decay-labelled substances and photographic emulsion containing silver bromide crystals to visual detector patterns of cellular structures or pathways.

Prokaryote

Single-celled organism (such as bacteria) lacking a true membrane-bound nucleus, containing a nucleoid and cell wall.

Eukaryote

Complex organism composed of cells containing a membrane-bound nucleus with DNA and distinct cellular organelles.

Integral Proteins

Membrane proteins incorporated directly within the phospholipid bilayer, anchored by hydrophobic interactions between lipids and non-polar amino acids.

Peripheral Proteins

Proteins located on the surface of the cell membrane that interact with cytoskeletal elements to influence cell shape and movement.

Fluid Mosaic Model

Model describing the cell membrane structure as flexible lipid molecules free to move independently, interspersed with integral, peripheral, or surface-attached proteins and carbohydrates.

Glycocalyx

Glycoprotein-polysaccharide fuzzy coat on the outer membrane surface of epithelial cells and bacteria that functions in protection, immunity, cell-cell recognition, and adhesion.

Microvilli

Finger-like extensions on the cell surface formed by cross-linked actin filaments that increase surface area for absorption in tissues like the intestines and kidneys.

Stereocilia

Long, irregular microvilli lacking internal motility structures or basal bodies that function to increase absorption surface area.

GAP Junctions

Intercellular junctions composed of six connexin proteins forming a cylindrical pore (connexon) that allows direct chemical communication and solute diffusion between adjacent cells.

Tight Junctions

Intercellular barriers in vertebrate epithelia formed by multiprotein complexes that physically seal adjacent plasma membranes to regulate water and solute transport.

Rough Endoplasmic Reticulum (RER)

Membrane-bound network of cisternae studded with outer ribosomes, specialized for manufacturing lysosomal enzymes, folding proteins, and synthesizing secreted/integral proteins.

Smooth Endoplasmic Reticulum (SER)

Ribosome-free endoplasmic reticulum involved in synthesizing lipids, phospholipids, and steroids, metabolizing carbohydrates, and regulating calcium ion concentration in muscle cells.

Golgi Apparatus

Organelle consisting of stacked cisternae with cis (entry) and trans (exit) faces that modifies, packages, and sorts proteins into membrane-bound vesicles for secretion or organelles.

Lysosomes

Membrane-bound organelles operating at a $pH$ of approximately $4.5$ containing hydrolytic enzymes used to digest waste material, cellular debris, and autophagic vacuoles.

Peroxisomes

Organelles derived from the ER that break down long-chain and branched-chain fatty acids via oxidation and eliminate toxic hydrogen peroxide ($H_2O_2$) using enzymes.

Mitochondria

Double-membrane organelles containing cristae, matrix, and mitochondrial DNA that generate cellular chemical energy (ATP) via aerobic respiration and the Krebs cycle.

Euchromatin

Lightly stained, less condensed nuclear chromatin containing active DNA undergoing transcription.

Heterochromatin

Darkly stained, tightly wound, condensed nuclear chromatin that represents transcriptionally inactive DNA.

Ribosomes

Non-membrane limited ribonucleoprotein complexes composed of small and large subunits that bind mRNA and tRNA to synthesize polypeptide chains.

Microtubules

Dynamic polymers of alpha and beta tubulin dimers nucleated by MTOCs that maintain cell shape, facilitate intracellular transport, and form cilia, flagella, and mitotic spindles.

Axoneme

Core structural arrangement of cilia and flagella consisting of a central pair of microtubules surrounded by nine peripheral doublets ($9+2$ structure) with axonemal dynein arms.

Centrosome

Primary microtubule-organizing center (MTOC) located near the nucleus in non-dividing cells, composed of a pair of centrioles (nine microtubule triplets) surrounded by pericentriolar material.

Facilitated Diffusion

Passive transport of polar molecules or large ions across cell membranes through gated channel proteins down a concentration gradient without consuming ATP.

Active Transport

Movement of molecules across a cell membrane against their concentration gradient using energy derived directly or indirectly from ATP hydrolysis.

Endomitosis

A form of endoreplication where a cell undergoes aspects of mitosis and sister chromatid separation but fails to complete telophase and cytokinesis, retaining multiple nuclei or duplicated genomes.

Cytokinesis

The division of the cell cytoplasm following mitosis, marked by the formation of a contractile ring cleavage furrow on the former metaphase plate.

Necrosis

Uncontrolled, accidental cell death resulting from external injury (toxins, trauma, hypoxia) characterized by cell swelling, plasma membrane disruption, content leakage, and inflammation.

Karyolysis

Nuclear alteration during necrosis where chromatin fades and degrades due to DNA loss.

Pyknosis

Nuclear alteration during necrosis characterized by nuclear shrinkage and extreme chromatin condensation.

Karyorrhexis

Nuclear change during necrotic cell death involving fragmentation of the shrunken, pyknotic nucleus.

Apoptosis

Programmed, non-inflammatory cell death initiated via intrinsic or extrinsic pathways that activate caspases, leading to cell shrinkage, DNA fragmentation, membrane blebbing, and phagocytic uptake.