Cell Biology Glossary

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--Mark Hill 08:40, 20 March 2009 (EST) This is a working page for developing a quick glossary of cell biology designed for students at undergraduate level. The student group project glossary template is more basic than this current page and is available on this page's discussion tab.




Cytoskeletal 43 kD protein forming the backbone of the cytoplasmic microfilament system and the thin filament system of muscle sacomeres. In humans, there are distinct muscle (4 alpha-skeletal, alpha-cardiac, alpha-smooth, gamma-smooth) and non-muscle (2 cytoskeletal beta-, gamma-) actin isoforms. Exists as globular actin monomer (G-actin) and microfilament polymer (F-actin). Lecture - Cytoskeleton 3 Microfilaments

actin-binding protein

Family of proteins that specifically bind actin within microfilament polymer (F-actin) or globular actin monomer (G-actin). Lecture - Cytoskeleton 3 Microfilaments

actin depolymerizing factor

(ADF) alternative name Cofilin, actin-binding protein that can disassemble actin by severing and depolymerizing actin filaments. Lecture - Cytoskeleton 3 Microfilaments

adult stem cell

An undifferentiated cell found in a differentiated tissue that can renew itself and (with certain limitations) differentiate to yield all the specialized cell types of the tissue from which it originated. Lecture - Stem Cells


The strength of binding between a ligand and a receptor: high affinity is strong binding, low affinity is a weak binding. Lecture - Signal 1 | Lecture - Signal 2 | Lecture - Signal 3


A phase of mitosis in which the chromosomes have separated and begun to be pulled to opposite poles of the cell. Lecture - Cell Division

anaphase promoting complex

(APC, cyclosome) Protein complex that is involved in the degradation of cohesin, allowing chromosome separation, and therefore beginning of anaphase in cell division. Lecture - Cell Division


(Greek, anoikis = "homelessness") A form of cell death that occurs when cells loose contact with the extracellular matrix (ECM). Extracellular Matrix 1 | Extracellular Matrix 2 | Lecture Cell Death 1


Acronym for Anaphase Promoting Complex.


A protein complex essential for actin assembly, generating new filaments and branch points. It is involved in cell motility in many cell processes. Lecture - Cytoskeleton 3 Microfilaments


A laboratory device to sterilize equipment, supplies and waste by subjecting them to high pressure steam at 121° C or more. Lab 8 - Tissue Culture


A eukaryotic cell cytoplasmic process used in organelle degradation. The other main cellular degradation process uses the proteasome. Journal - Autophagy



A family of calcium-dependent proteolytic enzymes, that are classified as non-lysosomal cysteine proteases. The enzyme can selectively cleave proteins in response to signaling (calcium signals) thought to be involved in cytoskeletal changes, cell cycle, gene expression and apoptotic cell death. Calpain 1 (micro-calpain) and 2 (m-calpain), are ubiquitously expressed and their activity is inhibited by calpastatin. PMID: 12843408


Only specific protein inhibitor of calpain

cell cycle

Term used to describe the changes that occur during the lifespan of a cell. It can be broadly divided into birth (cell division, mitosis, M phase) and the period of cell function (interphase). Lecture - Cell Cycle

cell cycle checkpoint

Lecture - Cell Cycle

cell wall

Structure present outside bacteria and plant cells. Gram-positive bacteria, composed of the cytoplasmic membrane and peptidoglycan layer. Gram-negative bacteria, have an additional outer membrane composed of integral membrane proteins, lipids, and lipopolysaccharides. Lecture - Eukaryotes and Prokaryotes


A carbohydrate that is found in plant cell walls Lecture - Eukaryotes and Prokaryotes



A nucleosome histone specifically located at the centromere.


Cytoplasmic microtubule organizing centre and thought to also regulate cell cycle events. Cytoskeleton 2 Microtubules PMID: 18437411


The green material found in chloroplasts that is active in photosynthesis. Lecture - Eukaryotes and Prokaryotes


The membrane-bound organelles containing chlorophyll found in photosynthetic organisms plants and fungi. Lecture - Eukaryotes and Prokaryotes


DNA and associated proteins, named because of its affinity for dyes. Cell Nucleus | Lecture - Cell Division


The condensed form of chromatin that is visible during mitosis and meiosis (cellular division). Cell Nucleus | Lecture - Cell Division


Acronym for Confocal Laser Scanning Microscope. Lab 7 - Confocal Microscopy


Alternative name Actin Depolymerizing Factor, actin-binding protein that can disassemble actin by severing and depolymerizing actin filaments. Lecture - Cytoskeleton 3 Microfilaments


A complex of proteins within the nucleus that hold sister chromatids together during cell division. It is degraded by separase, a protease. Lecture - Cell Division


A major extracellular matrix protein forming an insoluble fiber. Lecture - Extracellular Matrix 1


Cell culture term meaning to introduce micro-organisms to sterile articles, materials, cells or tissues. Lab - Tissue Culture 1

correlative light/electron microscopy

(CLEM) microscopy technique combining fluorescence light microscopy and electron microscopy for simultaneous observation of subcellular structures. Lab 2 - Microscopy Methods | PMID: 18817522

cyclase-associated protein

(CAP) actin-binding protein that works in conjunction with Cofilin. Lecture - Cytoskeleton 3 Microfilaments

cytochalasin D

A fungal metabolite which binds barbed end actin microfilaments and inhibits polymerization and depolymerization. Lecture - Cytoskeleton 3 Microfilaments


Collective term for the cytosol, organelles and cytoskeleton located outside the nucleus and under the plasma membrane. Lecture - Eukaryotes and Prokaryotes


Set of 3 filament systems intermediate filaments, actin filaments, and microtubules. Eukaryotic cells have a cytoplasmic and a nuclear cytoskeleton with different organisations and filaments. Cytoskeleton 2 Microtubules | Lecture - Cytoskeleton 3 Microfilaments


Term describing the fluid component of the cytoplasm that makes up the cytoplasm, excluding the organelles and cytoskeleton of the cytoplasm. Lecture - Eukaryotes and Prokaryotes



(di-h-HALI) Actin-binding compound derived from marine organisms, belong to a large group of structurally related marine macrolides. Experimental depletion of F-actin by F-actin severing and monomer sequestering activities. (see also halichondramide, HALI) Lecture - Cytoskeleton 3 Microfilaments


Acronym for deoxyribonucleic acid, the nucleotide polymer that forms a double-helix encoding the genetic information of organisms. Lecture - Cell Nucleus | Lecture - Cell Division


Dynamin family of GTPases member expressed in the nervous system and involved in many cellular pathways, implicated in clathrin-mediated endocytosis. Lecture - Cell Import - Endocytosis


Dynamin family of GTPases member ubiquitously expressed and involved in many cellular pathways, implicated in clathrin-mediated endocytosis. Lecture - Cell Import - Endocytosis



Acronym for ExtraCellular Matrix Extracellular Matrix 1 | Extracellular Matrix 2


Lecture - Cell Import - Endocytosis


A microtubule-stabilizing agent isolated from a soft coral (Eleutherobia sp.).

endoplasmic reticulum

The cytoplasmic organelle forming a single membrane enclosed space continuous with the outer membrane of the nuclear envelope. It has 2 functional domains described by the presence or absence of ribosomes, the rough endoplasmic reticulum and smooth endoplasmic reticulum respectively. Cell Export - Exocytosis

enzyme-linked receptors

Membrane receptors that use intracellular enzyme activity as part of the signaling pathway. Five classes of these cell receptors: receptor tyrosine kinases, tyrosine-kinase-associated receptors, receptor serine/threonine kinases, transmembrane guanylyl cyclases, and histidine-kinase-associated receptors. Lecture - Signal 1 | Lecture - Signal 2 | Lecture - Signal 3


DNA opened in interphase nucleus and transcriptionally active. Cell Nucleus



Large actin-crosslinking protein family that have roles in regulating actin cytoskeleton dynamics and cellular signaling. Protein structure has an N-terminal actin-binding domain followed by 24 Ig-like domains (IgFLNs), which interact with transmembrane receptors and cytosolic signaling proteins. Lecture - Cytoskeleton 3 Microfilaments


A fluorescent compound used in microscopy that that emits a specific color of light when illuminated by light. Lab 7 - Confocal Microscopy Table of Fluorochromes

fragile X mental retardation protein

(FMRP) an RNA-binding protein involved in several steps of RNA metabolism.


Unicellular or multicellular eukaryotic cells that obtain their food from external sources, and reproduce sexual or asexually. (yeast) Lecture - Eukaryotes and Prokaryotes


G0 phase

(growth 0 phase) Phase during interphase of cell cycle when cell has withdrawn from the normal cell cycle and not replicating. Lecture - Cell Cycle

G1 phase

(growth 1 phase) Phase during interphase of cell cycle where initial growth occurs following mitosis (M phase). Lecture - Cell Cycle

G2 phase

(growth 2 phase) Phase during interphase of cell cycle where growth occurs following duplication of DNA (S phase) and is followed by mitosis (M phase). Lecture - Cell Cycle

Golgi apparatus

Cytoplasmic organelle consisting of a stack of individual membrane enclosed spaces located near the nucleus. Functions to process and modify proteins for exocytosis and endocytosis pathways.Lecture - Cell Export - Exoocytosis | Lecture - Cell Import - Endocytosis



(HALI) Actin-binding compound derived from marine organisms, belong to a large group of structurally related marine macrolides. Experimental depletion of F-actin by F-actin severing and monomer sequestering activities. (see also dihydrohalichondramide, di-h-HALI) Lecture - Cytoskeleton 3 Microfilaments


Fusion of two different cell types. When muscle cells are fused with non-muscle cells, muscle gene expression is then activated in the non-muscle cell type.


DNA within the nucleus in a packed form which has limited transcriptional activity.Cell Nucleus | Cell Division


Cytoplasmic anaerobic organelle related to mitochondria adaptated to extreme cellular anaerobic lifestyle. Lecture - Eukaryotes and Prokaryotes |


intermediate filament

Cytoskeleton filament system required for cell mechanical stability and integrity. The name comes from the filaments being "intermediate" in cross-sectional size between microfilaments and microtubules. Lecture - Cytoskeleton - Intermediate Filaments



A sea sponge metabolite which binds and stabilizes actin microfilaments competitively with phalloidin. Also can cause nucleation. Lecture - Cytoskeleton 3 Microfilaments



Cytoskeleton intermediate filament protein of epithelial cells required for cell mechanical stability and integrity. Humans have 54 functional keratin genes. Lecture - Cytoskeleton - Intermediate Filaments | PMID: 18461349


(KIFs) are a superfamily of microtubule motor proteins that transport organelles and protein complexes in a microtubule- and ATP-dependent manner.

knockin mouse

A genetically engineered mouse in which genetic information is inserted into a particular locus in the genome. The mouse can now express this inserted gene/protein. Lab - Cell Knockout Methods

knockout mouse

A genetically engineered mouse in which genetic information is deleted from a particular locus in the genome. The mouse can now not express this modified or deleted gene and therefore protein. Lab - Cell Knockout Methods



A family of intermediate filament proteins that form the nuclear cytoskeleton. Lecture - Cell Nucleus | Lecture - Cytoskeleton - Intermediate Filaments


An extracellular matrix adhesive glycoprotein. Major component of epithelial basal lamina and also functions to direct cell migration and growth. Lecture - Extracellular Matrix 2


(Latrunculin A) A sea sponge metabolite which binds monomeric actin in a 1:1 complex and inhibits polymerization of actin microfilaments. Lecture - Cytoskeleton 3 Microfilaments


(Latin, ligare = to bind) A substance (substrate, activator, inhibitor, neurotransmitter) that binds to a receptor as part of a signaling process. Binding can have both different specificity and affinity. Lecture - Signal 1 | Lecture - Signal 2 | Lecture - Signal 3

lipid droplets

Cytoplasmic phospholipid enclosed depots of neutral lipids found in many cell types. PMID: 18546013

long noncoding RNA

These non-coding "genes" can have either no role or several identified roles: transcription can positively or negatively affect nearby genes expression, regulating activity or localization of proteins, processed to yield small RNAs or modulate other RNA processing.


Acronym for Laser Scanning Microscope. Lab 7 - Confocal Microscopy


Cytoplasmic organelle for the degradation of both endocytosed extracellular and autophagy of intracellular materials. Lecture - Cell Import - Endocytosis


M phase

(mitosis) Phase during cell cycle when a cell divides it follows the second growth period (G2 phase) and can then either cease replication (G0 phase) or enter a new cycle growth phase (G1 phase). Lecture - Cell Cycle | Lecture - Cell Division

macrophage colony-stimulating factor

(M-CSF) A growth factor cytokine required for the differentiation of monocyte lineage cells. It also promotes the formation of vascular networks in tumors.

Mallory-Denk bodies

(MDBs) liver disease associated protein aggregates consisting of ubiquitinated K8/K18, chaperones and sequestosome1/p62 (p62).

matrix metalloproteinases

(MMPs) secreted family of proteins that can degrade or modify components of the extracellular matrix, cellular receptors, and cytokines. In humans, 24 different MMPs have roles in normal and pathophysiological cellular events. Lecture - Extracellular Matrix


A phase of mitosis in when the chromosome pairs have lined up at the equator of the mitotic spindle. Lecture - Cell Division


A technique that allows the identification of overall cellular gene expression at the messenger RNA level. Lab 12 - Microarray


Cytoskeleton filament system required for cell shape and motility. The name comes from the filaments being the smallest in cross-sectional size of the three filament systems including intermediate filaments and microtubules. Lecture - Cytoskeleton 3 Microfilaments


Cytoskeleton filament system required for intracellular transport and motility. The name comes from the system filaments forming "tubes", they are also the largest in cross-sectional size of the three filament systems including microfilaments and intermediate filaments. Lecture - Cytoskeleton 3 Microtubules


A specialised form of cell division occurring in eukaryotic sexual reproduction, involving reduction of DNA content (diploid to haploid) to generate germ cells (oocyte and spermatazoa). Lecture - Cell Division


Cytoplasmic double membrane organelle, main functions include energy production from aerobic cell respiration and cell death by apoptosis. Lecture - Cell Energy Production - Mitochondria


(M phase) The term used to describe normal cell division, where the progeny cells are genetically identical to the parent cell, diploid. Historically the term was originally used by Walther Flemming in 1882 to characterize the appearance of paired chromosomes (Greek, mitos = "paired threads") Lecture - Cell Nucleus | Lecture - Cell Division

multivesicular bodies

(MVB) A type of cytoplasmic vesicle (200 - 500 nmdiameter) that occurs when part of an endosome membrane invaginates and buds into its own lumen forming smaller contained vesicles. These smaller vesicles are subsequently lost when the endosome fuses with a lysosome. Lecture - Endocytosis | PMID: 17506697



(entactin) Ubiquitous basement membrane component that binds laminin and consists of three globular domains (G1–G3) connected by extended segments. Lecture - Extracellular Matrix 2


The eukaryotic double membrane enclosed organelle that contains genetic material DNA and processes messenger RNA. Lecture - Cell Nucleus


Functional domain within the nucleus that contains genes encoding ribosomal RNA (rRNA), highly transcriptionally active and formed from DNA located at the ends of chromosomes. Lecture - Cell Nucleus


The structure formed by DNA and proteins that "packs DNA". Lecture - Cell Nucleus



(TP53) A multifunctional protein Mr 53 kDa regulating cell cycle arrest, apoptosis, senescence, DNA repair, and changes in cell metabolism. As a cell cycle regulator it recognizes and binds damaged DNA (single-stranded DNA, insertion/deletion mismatches, and free DNA ends) and also acts as a transcription factor activating p21 transcription. p53 also has an important role in apoptosis. Lecture - Cell Cycle OMIM 191170


A microtubule-stabilizing agent used in cancer therapy. Originally isolated from the Pacific yew tree (Taxus brevifolia) and called taxol, it is a member of the taxane family. Cytoskeleton 2 Microtubules


A fungal metabolite which binds and stabilizes actin microfilaments. Lecture - Cytoskeleton 3 Microfilaments

plasma membrane

(cell membrane) The lipid based bilayer forming the container for each cell Lecture - Compartments and Cell Membranes


A protein complex that degrades cellular proteins by proteolysis. Lecture - Cell Import - Endocytosis

protein bodies

(PBs) cytoplasmic plant organelles that accumulate storage proteins in seeds, formed from endoplasmic reticulum or vacuole. Lecture - Eukaryotes and Prokaryotes

protein kinases

Protein superfamily of enzymes that catalyze the transfer of phosphate from ATP or GTP onto serine, threonine, or tyrosine residues of their appropriate protein substrates. Lecture - Signaling 2


Human severe blistering skin disease caused by autoantibodies against desmosomal cadherins. Lecture - Cytoskeleton - Intermediate Filaments


restriction point

Cell cycle term used to describes the timepoint in G1 when cells no longer respond to withdrawal of growth factors by returning to G0, but progress to S phase. Lecture - Cell Cycle

retinoblastoma protein

(pRb, Rb) Protein with a role in cell cycle regulation acting as a tumor suppressor. Lecture - Cell Cycle OMIM 180200


Cytoplasmic structure formed from RNA and proteins that assembles to synthesise proteins. Ribosomes may be either free in the cytoplasm or attached to the endoplasmic reticulum, forming rough endoplasmic reticulum. Lecture - Exocytosis Ribosome


Acronym for ribonucleic acid, the molecule produced from DNA by transcription with structural and functional roles in protein synthesis. Cell Nucleus Cell Export - Exocytosis

rough endoplasmic reticulum

Functional compartment of the endoplasmic reticulum with ribosomes bound to the membrane surface. Functions to compartmentalize newly translated proteins and their post-translational modification. Cell Export - Exocytosis


S phase

Phase during interphase of cell cycle where DNA is duplicated prior to second growth period (G2 phase) and then mitosis (M phase). Lecture - Cell Cycle


A protein involved in cell division (anaphase). Functions in nuclear transport of separase and to inhibit its activity. Lecture - Cell Division


Family of secreted transmembrane and GPI-linked proteins that alter the cytoskeletal organization of micofilaments and microtubules. Humans have 20 semaphorins, defined by cysteine-rich semaphorin protein domains, expressed in the nervous system and other tissues.


Lecture - Cell Division


A highly conserved GTPase family found in fungi and animals implicated in a diversity of cellular processes including cytokinesis, formation of diffusion barriers and vesicle trafficking. Septin2 partially co-localises with actin bundles in mammalian interphase cells. Lecture - Cytoskeleton 3 Microfilaments

shiga toxin

A bacterial protein toxin produced by Shigella dysenteriae is transported directly from the plasma membrane to the endoplasmic reticulum by early endosomes and the Golgi apparatus. Lecture - Cell Import - Endocytosis | PMID: 11514628


(S1P) A protease functions to convert latent membrane-bound transcription factors to the active free form. In cartilage, necessary for specialized ER stress response of chondrocytes for the formation of normal cartilage and then endochondral ossification. PMID: 18025304

sterile technique

(aseptic) To carry out tissue culture procedures in such a way that contaminating microorganisms from the environment are not introduced to the culture. Lab 8 - Tissue Culture


Tissue culture term for the complete destruction of micro-organisms. Lab 8 - Tissue Culture


tissue culture

Term used to describe the research technique involving growth of cells experimentally outside the organism (in vitro = in glass). Tissue Culture 1 | Tissue Culture 2

trans-Golgi network

(TGN) Cell Import - Endocytosis


Cytoskeletal protein that sits in the major groove of the actin microfilament system. Many different different isoforms of this protein from 4 genes. Lecture - Cytoskeleton 3 Microfilaments | Cytoskeleton Exercise


Unicellular protozoan parasites that infect humans, animals, insects, and plants. Lecture - Eukaryotes and Prokaryotes | PMID: 18462016


Protein that forms microtubules, 55-kd polypeptides of α-tubulin (alpha-) and β-tubulin (beta-) form a a dimer, which is the basic subunit of microtubules. A third type of tubulin γ-tubulin (gamma-) is located at the centrosome. Cytoskeleton 2 Microtubules

tumour necrosis factor

(tumor necrosis factor, TNF)



(Ub) PMID: 17689064


The addition of ubiquitin to proteins that then targets the protein for destruction in the proteasome



Membrane-bound organelles in the cytoplasm that are used for storage and digestion. Lecture - Eukaryotes and Prokaryotes


Bacterial protein toxins produced by enterohemorrhagic strains of Escherichia coli these are transported directly from the plasma membrane to the endoplasmic reticulum by early endosomes and the Golgi apparatus. Lecture - Endocytosis | PMID: 11514628


Wiskott-Aldrich syndrome protein

(WASP) Protein involved in signal trasduction to the microfilament cytoskeleton. Other family members are N-WASP (neuronal Wiskott-Aldrich Syndrome protein) and Scar. Lecture - Cytoskeleton 3 Microfilaments



Acronym for xenotropic murine leukemia virus, a virus recently detected in prostate cancers and associated with chronic fatigue syndrome.