Adherens junctions (Zonula Adherens) (ZOHN-yoo-luh ad-HEER-enz): A continuous belt-like junction that encircles the apical circumference of many epithelial cells, located just basal to the tight junctions; it links the actin microfilaments of adjacent cells via cadherin proteins.

Adhesion belt (Adherens junction) (ad-HEE-zhun belt): The histological appearance of the adherens junction; it is a continuous band that links the apical microfilaments of adjacent epithelial cells, providing mechanical stability to the cell sheet.

Cadherin (transmembrane protein) (KAD-uh-rin): A type of transmembrane protein that is Ca2+-dependent; it extends from the plaque through the cell membrane and links to identical cadherins from the adjacent cell in both desmosomes and adherens junctions.

Centriole (SEN-tree-ohl): A pair of short, cylindrical structures, each composed of nine triplets of microtubules, located in the cell’s centrosome; they are crucial for organizing microtubules and forming the spindle fibers during cell division.

Connexon (Gap junctions) (kuh-NEK-son): An annular protein structure composed of six connexin subunits; two aligned connexons (one from each adjacent cell) form the complete channel that constitutes a gap junction.

Desmosomes (Macula Adherens) (DEZ-muh-sohmz/MAK-yoo-luh ad-HEER-enz): Strong spot-weld type junctions that anchor the intermediate filaments of adjacent cells to a dense cytoplasmic plaque; they provide great tensile strength and resistance to shear forces in tissues like the skin (epidermis) and cardiac muscle.

Gap junctions (gap JUNK-shunz): Channels formed by the alignment of protein complexes (connexons) between adjacent cells; they create a small, direct passageway for the rapid exchange of ions and small signaling molecules, allowing for electrical and metabolic coupling.

Golgi apparatus (Golgi complex) (GOHL-jee ap-uh-RAY-tus): A stack of flattened, membrane-bound sacs (cisternae) located near the nucleus; its function is to further process, sort, modify, package, and ship proteins and lipids synthesized by the rough endoplasmic reticulum. Site of post-translational modification of proteins (e.g., glycosylation, sulphation, phosphorylation). Consists of a cis/entry face, intermediate face, and trans/exit face.

Integral membrane protein (IN-tuh-grul MEM-brayn PROH-teen): a protein of the cell membrane that spans the entire length of the cell membrane and sits amongst the phospholipids; typically, integral membrane proteins form channels.

Intermediate filament (in-ter-MEE-dee-ut FIL-uh-ment): A durable, rope-like cytoskeletal filament (e.g., keratin, vimentin) composed of fibrous proteins; its primary function is to provide tensile strength and structural support, anchored at desmosomes.

Lysosome (LYE-suh-sohm): A small, spherical, membrane-bound organelle containing digestive hydrolytic enzymes; its function is to break down old organelles, foreign particles, and waste materials (intracellular digestion).

Microfilament (actin) (my-kroh-FIL-uh-ment): The thinnest component of the cytoskeleton, composed of globular actin subunits; its functions include forming the core of microvilli, supporting the adhesion belt (adherens junction), and participating in cell motility and contraction.

Mitochondrion (pl. Mitochondria) (my-tuh-KON-dree-un/my-tuh-KON-dree-uh): An oval-shaped organelle with an inner folded membrane (cristae) found in the cytoplasm; it is the primary site of aerobic cellular respiration and generates most of the cell’s adenosine triphosphate (ATP) energy. It is illegal to say mitochondria and not complete the sentence with “the powerhouse of the cell”.

Nucleolus (noo-KLEE-oh-lus): the electron dense (densely basophilic) structure inside the nucleus that is the site for ribosomal subunit synthesis.

Nucleus (NOO-klee-us): the largest organelle in cells with a nucleus (nucleated cell) which consists of a double membrane (nuclear membrane or envelope) encasing the gel-like substance (nucleoplasm), DNA in the form of chromatin, and nucleolus; the shape of the nucleus typically reflects the shape of the cell.

Organelle (OR-guh-nell): a component of a cell found within the cytoplasm that performs specific functions; they may be membranous (e.g., mitochondrion) or non-membranous (e.g., ribosome).

Phospholipid bilayer (fos-foh-LIP-id BUY-lay-er): the structure of the cell membrane that consists of two layers of phospholipids; due to the nature of the phospholipids, they self organise into a water loving (hydrophilic) outer and inner phosphate head surface with their water fearing (hydrophobic) lipid tails in the middle; the biochemical nature of the phospholipid bilayer regulates the entry and exit of substances into and out of the cell.

Plaque (cell junction) (plak): A dense layer of proteins located on the inner surface of the cell membrane at desmosomes and adherens junctions; this specialized region anchors the intermediate filaments or microfilaments to the junctional proteins.

Ribosomes (RYE-buh-sohmz): Small, non-membrane-bound particles composed of ribosomal RNA and protein; they are the cellular machinery responsible for synthesizing proteins from messenger RNA (translation). They are found free in the cytoplasm or attached to the rough endoplasmic reticulum. Consist of a small and large subunit. Synthesized in the nucleolus.

Rough endoplasmic reticulum (RER) (ruFF EN-doh-plaz-mik ruh-TIK-yuh-lum): A network of interconnected membranes and flattened sacs (cisternae) studded with ribosomes; its function is the synthesis, folding, and modification of proteins destined for secretion or insertion into membranes. Site of co- and post-translational modification of proteins, typically bound for secretion.

Smooth endoplasmic reticulum (smooth EN-doh-plaz-mik ruh-TIK-yuh-lum): the membranous organelle, part of the endoplasmic reticulum network, that is involved in steroid synthesis, detoxification and glycogen formation; it consists of two phosopholipid bilayer membranes with a fluid-filled space between them called the cistern (cisterae = plural).

Tight junctions (Zonula Occludens) (tyt JUNK-shunz/ZOHN-yoo-luh uh-KLOO-denz): The most apical type of junction in many epithelial cells; it forms a seal around the cell’s perimeter, created by the close fusion of adjacent cell membranes, to prevent the passage of molecules between cells (paracellular transport). Also keep membranous proteins at their required surface (e.g., apical surface membrane proteins).

Vesicle (VES-ih-kul): A small, membrane-bound sac within the cytoplasm; it is used to transport materials between organelles (e.g., from the rough endoplasmic reticulum to the Golgi apparatus) or to and from the cell membrane. E.g., endocytotic vesicle; secretory vesicle.