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A coiled secondary structure of a polypeptide chain formed by hydrogen bonding between amino acids separated by four residues.
A large family of membrane transport proteins characterized by a highly conserved ATP binding domain.
An abundant 43-kd protein that polymerizes to form cytoskeletal filaments.
Actin filaments that are crosslinked into closely packed arrays.
Actin filaments that are crosslinked into loose three-dimensional meshworks.
The energy required to raise a molecule to its transition state to undergo a chemical reaction.
The region of an enzyme that binds substrates and catalyzes an enzymatic reaction.
The transport of molecules in an energetically unfavorable direction across a membrane coupled to the hydrolysis of ATP or other source of energy.
A protein that binds to membrane receptors and mediates the formation of clathrin-coated vesicles.
A benign tumor arising from glandular epithelium.
An enzyme that catalyzes the formation of cyclic AMP from ATP.
A region of cell-cell adhesion at which the actin cytoskeleton is anchored to the plasma membrane.
A protein-serine/threonine kinase that is activated by PIP3 and plays a key role in signaling cell survival.
One copy of a gene.
The regulation of enzymes by small molecules that bind to a site distinct from the active site, changing the conformation and catalytic activity of the enzyme.
The generation of different mRNAs by varying the pattern of pre-mRNA splicing.
Monomeric building blocks of proteins, consisting of a carbon atom bound to a carboxyl group, an amino group, a hydrogen atom, and a distinctive side chain.
An enzyme that joins a specific amino acid to a tRNA molecule carrying the correct anticodon sequence.
A molecule that has both hydrophobic and hydrophilic regions.
The phase of mitosis during which sister chromatids separate and move to opposite poles of the spindle.
The movement of daughter chromosomes toward the spindle poles during mitosis.
The separation of the spindle poles during mitosis.
The formation of new blood vessels.
A protein produced by B lymphocytes that binds to a foreign molecule.
The nucleotide sequence of transfer RNA that forms complementary base pairs with a codon sequence on messenger RNA.
A molecule against which an antibody is directed.
The transport of two molecules in opposite directions across a membrane.
A DNA repair enzyme that cleaves next to apyrimidinic or apurinic sites in DNA.
The exposed free surface of a polarized epithelial cell.
An active process of programmed cell death, characterized by cleavage of chromosomal DNA, chromatin condensation, and fragmentation of both the nucleus and the cell.
A small flowering plant used as a model for plant molecular biology and development.
One of two major groups of prokaryotes; many species of archaebacteria live in extreme conditions similar to those prevalent on primitive Earth.
A GTP-binding protein required for vesicle budding from the trans-Golgi network.
Microtubules of the mitotic spindle that extend to the cell periphery.
An adenine-containing nucleoside triphosphate that serves as a store of free energy in the cell.
A membrane spanning protein complex that couples the energetically favorable transport of protons across a membrane to the synthesis of ATP.
A type of cell signaling in which a cell produces a growth factor to which it also responds.
The detection of radioisotopically labeled molecules by exposure to X-ray film.
The type of dynein found in cilia and flagella.
The fundamental structure of cilia and flagella composed of a central pair of microtubules surrounded by nine microtubule doublets.
A sheetlike secondary structure of a polypeptide chain, formed by hydrogen bonding between amino acids located in different regions of the polypeptide.
A bacterial virus.
A structure similar to a centriole that initiates the growth of axonemal microtubules and anchors cilia and flagella to the surface of the cell.
A sheetlike extracellular matrix that supports epithelial cells and surrounds muscle cells, adipose cells, and peripheral nerves.
A mechanism of DNA repair in which single damaged bases are removed from a DNA molecule.
See basal lamina.
The surface region of a polarized epithelial cell that is in contact with adjacent cells or the extracellular matrix.
A tumor that remains confined to its site of origin.
A group of cell adhesion molecules that form stable cell-cell junctions at adherens junctions and desmosomes.
A nematode used as a simple multicellular model for development.
A calcium-binding protein.
A series of reactions by which six molecules of CO2 are converted into glucose.
An enzyme that degrades cyclic AMP.
See protein kinase A.
A molecule with the formula (CH2O)n. Carbohydrates include both simple sugars and polysaccharides.
A cancer-inducing agent.
A cancer of epithelial cells.
A phospholipid containing four hydrocarbon chains.
Proteins that selectively bind and transport small molecules across a membrane.
A family of proteases that bring about programmed cell death.
An enzyme that decomposes hydrogen peroxide.
Small invaginations of the plasma membrane that may be involved in endocytosis.
A protein-serine/threonine kinase that is a key regulator of mitosis in eukaryotic cells.
Cyclin dependent protein kinases that control the cell cycle of eukaryotes. See also Cdc2.
A collection of recombinant cDNA clones.
Transmembrane proteins that mediate cell-cell interactions.
The actin network underlying the plasma membrane.
A rigid, porous structure forming an external layer that provides structural support to bacteria, fungi, and plant cells.
The principal structural component of the plant cell wall, a linear polymer of glucose residues linked by b(1→ 4) glycosidic bonds.
A cylindrical structure consisting of nine triplets of microtubules in the centrosomes of most animal cells.
A specialized chromosomal region that connects sister chromatids and attaches them to the mitotic spindle.
The microtubule-organizing center in animal cells.
An enzyme that degrades cGMP.
Proteins that form pores through a membrane.
A protein that facilitates the correct folding or assembly of other proteins.
A family of heat-shock proteins within which protein folding takes place.
The generation of ATP from energy stored in a proton gradient across a membrane.
Sites of recombination that link homologous chromosomes during meiosis.
A polymer of N-acetylglucosamine residues that is the principal component of fungal cell walls.
The major photosynthetic pigment of plant cells.
The organelle responsible for photosynthesis in the cells of plants and green algae.
A lipid consisting of four hydrocarbon rings. Cholesterol is a major constituent of animal cell plasma membranes and the precursor of steroid hormones.
The fibrous complex of eukaryotic DNA and histone proteins. See histones, nucleosome, and chromatosome.
A chromatin subunit consisting of 166 base pairs of DNA wrapped around a histone core and held in place by a linker histone.
A microtubule-based projection of the plasma membrane that moves a cell through fluid or fluid over a cell.
A regulatory DNA sequence that serves as a protein binding site and controls the transcription of adjacent genes.
A series of reactions in which acetyl CoA is oxidized to CO2. The central pathway of oxidative metabolism.
A protein that coats the cytoplasmic surface of cell membranes and assembles into basketlike lattices that drive vesicle budding.
See recombinant molecule.
The basic unit of the genetic code; one of the 64 nucleotide triplets that code for an amino acid or stop sequence.
A coenzyme that functions as a carrier of acyl groups in metabolic reactions.
A small lipid-soluble molecule that carries electrons between protein complexes in the mitochondrial electron transport chain.
Low-molecular-weight organic molecules that work together with enzymes to catalyze biological reactions.
A complex of proteins that maintain the connection between sister chromatids.
A drug that inhibits the polymerization of microtubules.
A drug that inhibits the polymerization of microtubules.
The major structural protein of the extracellular matrix.
Plant cells characterized by thick cell walls; they provide structural support to the plant.
A DNA molecule that is complementary to an mRNA molecule, synthesized in vitro by reverse transcriptase.
The inhibition of movement or proliferation of normal cells that results from cell-cell contact.
A structure of actin and myosin II that forms beneath the plasma membrane during mitosis and mediates cytokinesis.
Steroid hormones produced by the adrenal gland.
A vector that contains bacteriophage 𝛌 sequences, antibiotic resistance sequences, and an origin of replication. It can accommodate large DNA inserts of up to 45 kb.
A fold in the inner mitochondrial membrane extending into the matrix.
The largest and most complex prokaryotes in which photosynthesis is believed to have evolved.
Adenosine monophosphate in which the phosphate group is covalently bound to both the 3´ and 5´ carbon atoms, forming a cyclic structure; an important second messenger in the response of cells to a variety of hormones.
An electron transport pathway associated with photosystem I that produces ATP without the synthesis of NADPH.
Guanosine monophosphate in which the phosphate group is covalently bound to both the 3´ and 5´ carbon atoms, forming a cyclic structure; an important second messenger in the response of cells to a variety of hormones and in vision.
A drug that blocks the elongation of actin filaments.
A protein complex in the electron transport chain that accepts electrons from cytochrome c and transfers them to O2.
Growth factors that regulate blood cells and lymphocytes.
A pyrimidine that base-pairs with guanine.
A network of protein filaments that extends throughout the cytoplasm of eukaryotic cells. It provides the structural framework of the cell and is responsible for cell movements.
A method of separating particles by centrifugation through a gradient of a dense substance, such as sucrose or cesium chloride.
The genetic material of the cell.
A region of contact between epithelial cells at which keratin filaments are anchored to the plasma membrane. See also hemidesmosome.
A secondary messenger formed from the hydrolysis of PIP2 that activates protein kinase C.
The final stage of the prophase of meiosis I during which the chromosomes fully condense and the cell progresses to metaphase.
A unicellular eukaryote used for studies of cell movement and cell-cell signaling.
An organism or cell that carries two copies of each chromosome.
The stage of mieosis I during which homologous chromosomes separate along their length but remain associated at chiasmata.
A DNA repair enzyme that cleaves the bond linking a purine or pyrimidine to the deoxyribose of the backbone of a DNA molecule.
An enzyme that seals breaks in DNA strands.
An enzyme catalyzing the synthesis of DNA.
A lipid molecule in the endoplasmic reticulum upon which oligosaccharides are assembled for the glycosylation of proteins.
Compact, globular regions of proteins that are the basic units of tertiary structure.
A species of fruit fly commonly used for studies of animal genetics and development.
A motor protein that moves along microtubules towards the minus end.
A species of bacteria used as a model for biochemistry and molecular biology.
A family of transcription factors that regulate the expression of genes involved in cell cycle progression and DNA replication.
An insect steroid hormone that triggers metamorphosis.
The outer germ layer; gives rise to tissues that include the skin and nervous system.
A class of lipids, including prostaglandins, prostacyclins, thromboxanes, and leukotrienes, that act in autocrine and paracrine signaling.
A difference in chemical concentration and electric potential across a membrane.
A type of microscopy that uses an electron beam to form an image. In transmission electron microscopy, a beam of electrons is passed through a specimen stained with heavy metals. In scanning electron microscopy, electrons scattered from the surface of a specimen are analyzed to generate a three-dimensional image.
A series of carriers through which electrons are transported from a higher to a lower energy state.
Cells cultured from early embryos.
A type of cell-cell signaling in which endocrine cells secrete hormones that are carried by the circulation to distant target cells.
The uptake of extracellular material in vesicles formed from the plasma membrane.
The inner germ layer; gives rise to internal organs.
An extensive network of membrane-enclosed tubules and sacs involved in protein sorting and processing as well as in lipid synthesis.
A vesicular compartment involved in the sorting and transport to lysosomes of material taken up by endocytosis.
A symbiotic relationship in which one cell resides within a larger cell.
A transcriptional regulatory sequence that can be located at a site distant from the promoter.
Proteins or RNAs that catalyze biological reactions.
Cells forming a protective layer on the surfaces of plants and animals.
A growth factor that stimulates cell proliferation.
Cells forming sheets (epithelial tissue) that cover the surface of the body and line internal organs.
The separation of particles on the basis of density by centrifugation to equilibrium in a gradient of a dense substance.
Red blood cells.
A steroid hormone produced by the ovaries.
One of two major groups of prokaryotes, including most common species of bacteria.
Decondensed, transcriptionally active interphase chromatin.
Cells that have a nuclear envelope, cytoplasmic organelles, and a cytoskeleton.
A segment of a gene that contains a coding sequence.
An enzyme that hydrolyzes DNA molecules in either the 5´ to 3´ or 3´ to 5´ direction.
A receptor protein that recognizes nuclear export signals and directs transport from the nucleus to the cytosol.
Secreted proteins and polysaccharides that fill spaces between cells and bind cells and tissues together.
The transport of molecules across a membrane by carrier or channel proteins.
A nonreceptor protein-tyrosine kinase that plays a key role in integrin signaling.
See triacylglycerols.
Long hydrocarbon chains usually linked to a carboxyl group (COO-).
A type of allosteric regulation in which the product of a metabolic pathway inhibits the activity of an enzyme involved in its synthesis.
A cell type found in connective tissue.
The principal adhesion protein of the extracellular matrix.
A thin projection of the plasma membrane supported by actin bundles.
A microtubule-based projection of the plasma membrane that is responsible for cell movement.
A coenzyme that functions as an electron carrier in oxidation/reduction reactions.
An instrument that measures the fluoresence intensity of individual cells.
A model of membrane structure in which proteins are inserted in a fluid phospholipid bilayer.
The nonselective uptake of extracellular fluids during endocytosis.
A method used to localize genes on chromosomes using fluorescent probes.
Type of microscopy in which molecules are detected based on the emission of fluorescent light.
A site of attachment of cells to the extracellular matrix at which integrins are linked to bundles of actin filaments.
Method of electron microscopy in which specimens are frozen in liquid nitrogen and then fractured to split the lipid bilayer, revealing the interior faces of cell membranes.
A family of cell signaling proteins regulated by guanine nucleotide binding.
A receptor characterized by seven membrane-spanning a helices. Ligand binding causes a conformational change that activates a G protein.
A quiescent state in which cells remain metabolically active but do not proliferate.
The phase of the cell cycle between the end of mitosis and the begining of DNA synthesis.
A plasma membrane channel forming a direct cytoplasmic connection between adjacent cells.
A segment of DNA that encodes a polypeptide chain or an RNA molecule.
An increase in the number of copies of a gene resulting from the repeated replication of a region of DNA.
The introduction of foreign DNA into a cell.
The exchange of segments between DNA molecules that share extensive sequence homology.
Transcription factors that are part of the general transcription machinery.
The correspondence between nucleotide triplets and amino acids in proteins.
The regulation of genes whose expression depends on whether they are maternally or paternally inherited, apparently controlled by DNA methylation.
A collection of recombinant DNA clones that collectively contain the genome of an organism.
The genetic composition of an organism.
The thermodynamic function that combines the effects of enthalpy and entropy to predict the energetically favorable direction of a chemical reaction.
The synthesis of glucose.
Phospholipids consisting of two fatty acids bound to a glycerol molecule.
A carbohydrate coat covering the cell surface.
A polymer of glucose residues that is the principal storage form of carbohydrates in animals.
A lipid consisting of two hydrocarbon chains linked to a polar head group containing carbohydrates.
The anaerobic breakdown of glucose.
A protein linked to oligosaccharides.
A gel-forming polysaccharide of the extracellular matrix.
The bond formed between sugar residues in oligosaccharides or polysaccharides.
The addition of carbohydrates to proteins.
Glycolipids containing phosphatidylinositol that anchor proteins to the external face of the plasma membrane.
The conversion of fatty acids to carbohydrates in plants.
A cytoplasmic organelle involved in the processing and sorting of proteins and lipids. In plant cells, it is also the site of the synthesis of cell wall polysaccharides.
A protein from jellyfish that is commonly used as a marker for fluorescence microscopy.
Polypeptides that control animal cell growth and differentiation.
A purine that base-pairs with cytosine.
An enzyme that catalyzes the formation of cyclic GMP from GTP.
An organism or cell that has one copy of each chromosome.
An enzyme that catalyzes the unwinding of DNA.
A polysaccharide that crosslinks cellulose microfibrils in plant cell walls.
A region of contact between cells and the extracellular matrix at which keratin filaments are attached to integrin.
Condensed, transcriptionally inactive chromatin.
Chemical bonds that release a large amount of free energy when they are hydrolyzed.
Proteins that package DNA in eukaryotic chromosomes.
and HMG-17
Nonhistone chromosomal proteins associated with decondensed transcriptionally active chromatin.
The central intermediate in recombination, consisting of a crossed-strand structure formed by homologous base pairing between strands of two DNA moleucles.
Conserved DNA sequences of 180 base pairs that encode homeodomains.
A type of DNA binding domain found in transcription factors that regulate gene expression during embryonic development.
Recombination between segments of DNA with homologous nucleotide sequences.
Signaling molecules produced by endocrine glands that act on cells at distant body sites.
Soluble in water.
Not soluble in water.
A method that uses antibodies to detect proteins separated by SDS-polyacrylamide gel electrophoresis.
See antibody.
The use of antibodies to isolate proteins.
A receptor protein that recognizes nuclear localization signals and directs nuclear import.
The use of radioactive or fluorescent probes to detect RNA or DNA sequences in cell extracts, chromosomes, or intact cells.
Protein synthesis in a cell-free extract.
A second messenger, formed from the hydrolysis of PIP2, that signals the release of calcium ions from the endoplasmic reticulum.
Proteins embedded within the lipid bilayer of cell membranes.
A transmembrane protein that mediates the adhesion of cells to the extracellular matrix.
A cytoskeletal filament about 10 nm in diameter that provides mechanical strength to cells in tissues. See also keratins and neurofilaments.
The period of the cell cycle between mitoses that includes G1, S, and G2 phases.
A chain of reactions that transmits chemical signals from the cell surface to their intracellular targets.
A protein that mediates the rapid passage of ions across a membrane by forming open pores through the phospholipid bilayer.
A protein that couples ATP hydrolysis to the transport of ions across a membrane.
A family of nonreceptor protein-tyrosine kinases associated with cytokine receptors.
A type of intermediate filament protein of epithelial cells.
One thousand nucleotides or nucleotide base pairs.
A motor protein that moves along microtubules towards the plus end.
A specialized structure consisting of proteins attached to a centromere that mediates the attachment and movement of chromosomes along the mitotic spindle.
Microtubules of the mito-tic spindle that attach to condensed chromosomes at their centromeres.
See citric acid cycle.
The strand of DNA synthesized opposite to the direction of movement of the replication fork by ligation of Okazaki fragments.
A broad, actin-based extension of the plasma membrane involved in the movement of fibroblasts.
The principal adhesion protein of basal laminae.
Intermediate filament proteins that form the nuclear lamina.
The strand of DNA synthesized continuously in the direction of movement of the replication fork.
The initial stage of the extended prophase of meiosis I during which homologous chromosomes pair before condensation.
A protein dimerization domain containing repeated leucine residues; found in many transcription factors.
Cancer arising from the precursors of circulating blood cells.
A molecule that binds to a receptor.
The reactions of photosynthesis in which solar energy drives the synthesis of ATP and NADPH.
A polymer of phenolic residues that strengthens secondary cell walls.
Hydrophobic molecules that function as energy storage molecules, signaling molecules, and the major components of cell membranes.
DNA sequences found at the ends of retroviral and retrotransposon DNA that are direct repeats of several hundred nucleotides resulting from reverse transcriptase activity.
A blood cell that functions in the immune response. B lymphocytes produce antibodies and T lymphocytes are responsible for cell mediated immunity.
A cancer of lymphoid cells.
A viral infection leading to integration of an inactive copy of viral DNA into the cell genome.
A cytoplasmic organelle containing enzymes that break down biological polymers.
The mitotic phase of the cell cycle.
A type of white blood cell specialized for phagocytosis.
A tumor that invades normal tissue and spreads throughout the body.
A family of mitogen-activated protein-serine/threonine kinases that are ubiquitous regulators of cell growth and differentiation.
The inner mitochondrial space.
One million nucleotides or nucleotide base pairs.
Growth factors associated with the plasma membrane that function as signaling molecules during cell-cell contact.
The middle germ layer; gives rise to connective tissues and the hematopoietic system.
An RNA molecule that serves as a template for protein synthesis.
The phase of mitosis during which the chromosomes are aligned on a metaphase plate in the center of the cell.
Spread of cancer cells through the blood or lymphatic system to other organ sites.
A structure consisting of GTP and methylated sugars that is added to the 5´ ends of eukaryotic mRNAs.
A cytoskeleton filament composed of actin.
See filopodium.
A cytoskeletal component formed by the polymerization of tubulin into rigid, hollow rods about 25 nm in diameter.
An anchoring point near the center of the cell from which most microtubules extend outward.
An actin-based protrusion of the plasma membrane, abundant on the surfaces of cells involved in absorption.
A repair system that removes mismatched bases from newly synthesized DNA strands.
Cytoplasmic organelles responsible for synthesis of most of the ATP in eukaryotic cells by oxidative phosphorylation.
Nuclear division.
An array of microtubules extending from the spindle poles that is responsible for separating daughter chromosomes during mitosis. See also kinetochore microtubules, polar microtubules, and astral microtubules.
A protein that generates force and movement by converting chemical energy to mechanical energy.
Messenger RNAs that encode a single polypeptide chain.
An antibody produced by a clonal line of B lymphocytes.
Simple sugars with the basic formula of (CH2O)n.
A chemical that induces a high frequency of mutations.
A genetic alteration.
A protein that interacts with actin as a molecular motor.
The addition of myristic acid (a 14-carbon fatty acid) to the N-terminal glycine residue of a polypeptide chain.
The relationship between ion concentration and membrane potential.
A type of intermediate filament that supports the axons of nerve cells.
A nerve cell specialized to receive and transmit signals throughout the body.
A small, hydrophilic molecule that carries a signal from a stimulated neuron to a target cell at a synapse.
A protein that links microtubule doublets to each other in the axoneme.
A coenzyme that functions as an electron carrier in oxidation/reduction reactions.
The reduction of atmospheric nitrogen (N2) to NH3.
An intracellular protein-tyrosine kinase.
The barrier separating the nucleus from the cytoplasm, composed of an inner and outer membrane, a nuclear lamina, and nuclear pore complexes.
An amino acid sequence that targets proteins for transport from the nucleus to the cytosol.
A meshwork of lamin filaments providing structural support to the nucleus.
An amino acid sequence that targets proteins for transportation from the cytoplasm to the nucleus.
Membranes forming the nuclear envelope; the outer nuclear membrane is continuous with the endoplasmic reticulum and the inner nuclear membrane is adjacent to the nuclear lamina.
A large structure forming a transport channel through the nuclear envelope.
The formation of double stranded DNA and/or RNA molecules by complementary base pairing.
The nuclear site of rRNA transcription, processing, and ribosome assembly.
A purine or pyrimidine base linked to a sugar (ribose or deoxyribose).
The basic structural unit of chromatin consisting of DNA wrapped around a histone core.
Proteins that disrupt chromatin structure, allowing transcription factors to bind nucleosomal DNA.
A phosphorylated nucleoside.
A mechanism of DNA repair in which oligonucleotides containing damaged bases are removed from a DNA molecule.
The most prominent organelle of eukaryotic cells; contains the genetic material.
Short DNA fragments that are joined to form the lagging strand of DNA.
A short polymer of only a few nucleotides.
A short polymer of only a few sugars.
A regulatory sequence of DNA that controls transcription of an operon.
A group of adjacent genes transcribed as a single mRNA.
A specific DNA sequence that serves as a binding site for proteins that initiate replication.
A protein complex that initiates DNA replication at yeast origins.
The synthesis of ATP from ADP coupled to the energetically favorable transfer of electrons to molecular oxygen as the final acceptor in an electron transport chain.
A transcription factor (encoded by the p53 tumor suppressor gene) that arrests the cell cycle in G1 in response to damaged DNA and is required for apoptosis induced by a variety of stimuli.
The stage of meiosis I during which recombination takes place between homologous chromosomes.
The addition of palmitic acid (a 16-carbon fatty acid) to cysteine residues of a polypeptide chain.
Local cell-cell signaling in which a molecule released by one cell acts on a neighboring target cell.
A type of plant cell responsible for most metabolic activities.
The diffusion of small hydrophobic molecules through a phospholipid bilayer.
The transport of molecules across a membrane in the energetically favorable direction.
A gel-forming polysaccharide in plant cell walls.
The bond joining amino acids in polypeptide chains.
The principal component of bacterial cell walls consisting of linear polysaccharide chains crosslinked by short peptides.
An enzyme that facilitates protein folding by catalyzing the cis-trans isomerization of prolyl peptide bonds.
The material in the centrosome that initiates microtubule assembly.
Proteins indirectly associated with cell membranes by protein-protein interactions.
A cytoplasmic organelle specialized for carrying out oxidative reactions.
The uptake of large particles, such as bacteria, by a cell.
A drug that binds to actin filaments and prevents their disassembly.
The physical appearance of an organism.
A class of tumor promoters that stimulate protein kinase C by acting as analogs of diacylglycerol.
An enzyme that phosphorylates PIP2, yielding the second messenger phosphatidylinositol 3,4,5-trisphosphate (PIP3).
A minor phospholipid component of the inner leaflet of the plasma membrane. Hormones and growth factors stimulate its hydrolysis by phospholipase C, yielding the second messengers diacylglycerol and inositol trisphosphate.
A bond between the 5´-phosphate of one nucleotide and the 3´-hydroxyl of another.
An enzyme that hydrolyzes PIP2 to form the second messengers diacylglycerol and inositol trisphosphate.
The basic structure of biological membranes, in which the hydrophobic tails of phospholipids are buried in the interior of the membrane and their polar head groups are exposed to the aqueous solution on either side.
A protein that transports phospholipid molecules between cell membranes.
The principal components of cell membranes, consisting of two hydrocarbon chains (usually fatty acids) joined to a polar head group containing phosphate.
The addition of a phosphate group to a molecule.
A mechanism of DNA repair in which solar energy is used to split pyrimidine dimers.
The process by which cells harness energy from sunlight and synthesize glucose from CO2 and water.
The uptake of fluids or molecules into a cell by small vesicles.
A group of small molecules that coordinate the responses of plant tissues to environmental signals.
A phospholipid bilayer with associated proteins that surrounds the cell.
A family of phospholipids that have an ether bond and an ester bond.
A small, circular DNA molecule capable of independent replication in a host cell.
A cytoplasmic connection between adjacent plant cells formed by a continuous region of the plasma membrane.
A family of plant organelles including chloroplasts, chromoplasts, leucoplasts, amyloplasts, and elaioplasts.
A growth factor released by platelets during blood clotting to stimulate the proliferation of fibroblasts.
Microtubules of the mitotic spindle that overlap in the center of the cell and push the spindle poles apart.
A tract of about 200 adenine nucleotides added to the 3´ ends of eukaryotic mRNAs.
The process of adding a poly-A tail to a pre-mRNA.
Messenger RNAs that encode multiple polypeptide chains.
A method for amplifying a region of DNA by repeated cycles of DNA synthesis in vitro.
A polymer containing up to millions of nucleotides.
A benign tumor projecting from an epithelial surface.
A polymer of amino acids.
A polymer containing hundreds or thousands of sugars.
A series of ribosomes translating a messenger RNA.
The primary transcripts that are processed to form messenger RNAs in eukaryotic cells.
The primary transcript, which is cleaved to form individual ribosomal RNAs (the 28S, 18S, and 5.8S rRNAs of eukaryotic cells).
The primary transcript, which is cleaved to form transfer RNAs.
The addition of specific types of lipids (prenyl groups) to C terminal cysteine residues of a polypeptide chain.
The sequence of amino acids in a polypeptide chain.
An RNA polymerase used to initiate DNA synthesis.
A psuedogene that has arisen by reverse transcription of mRNA.
A steroid hormone produced by the ovaries.
A normal physiological form of cell death characterized by apoptosis.
Cells lacking a nuclear envelope, cytoplasmic organelles, and a cytoskeleton (primarily bacteria).
A transition period between prophase and metaphase during which the microtubules of the mitotic spindle attach to the kinetochores and the chromosomes shuffle until they align in the center of the cell.
A DNA sequence to which RNA polymerase binds to initiate transcription.
Two haploid nuclei in a newly fertilized egg.
The selective removal of mismatched bases by DNA polymerase.
The beginning phase of mitosis, marked by the appearance of condensed chromosomes and the development of the mitotic spindle.
Small molecules bound to proteins.
An enzyme that catalyzes the formation and breakage of disulfide (S–S) linkages.
An enzyme that phosphorylates proteins by transferring a phosphate group from ATP.
A protein kinase regulated by cyclic AMP.
A family of protein-serine/threonine kinases that are activated by diacylglycerol and Ca2+ and function in intracellular signal transduction.
An enzyme that reverses the action of protein kinases by removing phosphate groups from phosphorylated amino acid residues.
A protein kinase that phosphorylates serine and threonine residues.
A protein kinase that phosphorylates tyrosine residues.
An enzyme that removes the phosphate groups from phosphotyrosine residues.
Polypeptides with a unique amino acid sequence.
A protein linked to glycosaminoglycans.
Degradation of polypeptide chains.
A nonfunctional gene copy.
An actin-based extension of the plasma membrane responsible for phagocytosis and amoeboid movement.
A lipid phosphatase that dephosphorylates PIP3 and acts as a tumor suppressor.
A common form of DNA damage caused by UV light in which adjacent pyrimidines are joined to form a dimer.
The interactions between polypeptide chains in proteins consisting of more than one polypeptide.
A protein-serine/threonine kinase (encoded by the raf oncogene) that is activated by Ras and leads to activation of MAP kinase.
A small GTP-binding protein involved in nuclear import and export.
A family of small GTP binding proteins (encoded by the ras oncogenes) that couple growth factor receptors to intracellular targets, including the Raf protein-serine/threonine kinase and the MAP kinase pathway.
A transcriptional regulatory protein encoded by a tumor suppressor gene that was identified by the genetic analysis of retinoblastoma.
Membrane-spanning protein-tyrosine kinases that are receptors for extracellular ligands.
The selective uptake of macromolecules that bind to cell surface receptors that concentrate in clathrin-coated pits.
A collection of genomic or cDNA clones.
A DNA insert joined to a vector.
The exchange of genetic material.
The region of DNA synthesis where the parental strands separate and two new daughter strands elongate.
A regulatory molecule that blocks transcription.
An enzyme that cleaves DNA at a specific sequence.
The locations of restriction endonuclease cleavage sites on a DNA molecule.
A regulatory point in animal cell cycles that occurs late in G1. After this point, a cell is committed to entering S and undergoing one cell division cycle.
A transposable element that moves via reverse transcription of an RNA intermediate.
A virus that replicates by making a DNA copy of its RNA genome by reverse transcription.
A DNA polymerase that uses an RNA template.
A G protein-coupled photoreceptor in retinal rod cells that activates transducin in response to light absorption.
A polymer of ribonucleotides.
The RNA component of ribosomes.
Particles composed of RNA and proteins that are the sites of protein synthesis.
An RNA enzyme.
RNA processing events other than splicing that alter the protein coding sequences of mRNAs.
An enzyme that catalyzes the synthesis of RNA.
The joining of exons in a precursor RNA molecule.
An enzyme that degrades the RNA strand of RNA-DNA hybrid molecules.
The region of the endoplasmic reticulum covered with ribosomes and involved in protein metabolism.
An acutely transforming retrovirus, in which the first oncogene was identified.
Calcium channels in muscle and nerve cells that open in response to changes in membrane potential.
The phase of the cell cycle during which DNA replication occurs.
A cancer of cells of connective tissue.
A specialized network of membranes in muscle cells that stores a high concentration of Ca2+.
See electron microscopy.
Plant cells characterized by thick cell walls that provide structural support to the plant.
A commonly used method to separate proteins by gel electrophoresis on the basis of size.
A compound whose metabolism is modified as a result of a ligand-receptor interaction; it functions as a signal transducer by regulating other intracellular processes.
The regular arrangement of amino acids within localized regions of a polypeptide chain. See a helix and b sheet.
Membrane-enclosed sacs that transport proteins from the Golgi apparatus to the cell surface.
Cell adhesion molecules that recognize oligosaccharides exposed on the cell surface.
The ability of some RNAs to catalyze the removal of their own introns.
A protein domain of approximately 100 amino acids that binds phosphotyrosine-containing peptides.
The sequence prior to the initiation site that correctly aligns bacterial mRNAs on ribosomes.
A recognition determinant formed by the three-dimensional folding of a polypeptide chain.
An enzyme that removes the signal sequence of a polypeptide chain by proteolysis.
A particle composed of proteins and 7SL RNA that binds to signal sequences and targets polypeptide chains to the endoplasmic reticulum.
A hydrophobic sequence at the amino terminus of a polypeptide chain that targets it for secretion in bacteria or incorporation into the endoplasmic reticulum in eukaryotic cells.
Recombination mediated by proteins that recognize specific DNA sequences.
The major site of lipid synthesis in eukaryotic cells.
A method in which radioactive probes are used to detect specific DNA fragments that have been separated by gel electrophoresis.
A major actin-binding protein of the cell cortex.
A phospholipid consisting of two hydrocarbon chains bound to a polar head group containing serine.
A nonreceptor protein-tyrosine kinase encoded by the oncogene (src ) of Rous sarcoma virus.
A polymer of glucose residues that is the principal storage form of carbohydrates in plants.
A regulatory point in the yeast cell cycle that occurs late in G1. After this point a cell is committed to entering S and undergoing one cell division cycle.
Trancription factors that have an SH2 domain and are activated by tyrosine phosphorylation, which promotes their translocation from the cytoplasm to the nucleus.
A cell that divides to produce daughter cells that can either differentiate or remain as stem cells.
A specialized microvillus of auditory hair cells.
A group of hydrophobic hormones that are derivatives of cholesterol.
A family of transcription factors that regulate gene expression in response to steroids and related hormones.
A molecule acted upon by an enzyme.
The transport of two molecules in the same direction across a membrane.
The junction between a neuron and another cell, across which information is carried by neurotransmitters.
The association of homologous chromosomes during meiosis.
A secretory vesicle that releases neurotransmitters at a synapse.
A zipperlike protein structure that forms along the length of paired homologous chromosomes during meiosis.
A T lymphocyte surface protein that recognizes antigens expressed on the surface of other cells.
A regulatory DNA sequence found in the promoters of many eukaryotic genes transcribed by RNA polymerase II.
A basal transcription factor that binds directly to the TATA box.
A drug that binds to and stabilizes microtubules.
A reverse transcriptase that synthesizes telomeric repeat sequences at the ends of chromosomes from its own RNA template.
Repeats of simple-sequence DNA that maintain the ends of linear chromosomes.
The final phase of mitosis, during which the nuclei re-form and chromosomes decondense.
A cell expressing a protein that is functional at one temperature but not at another, whereas the normal protein is functional at both temperatures.
The three-dimensional folding of a polypeptide chain that gives the protein its functional form.
A steroid hormone produced by the testis.
The innermost membrane of chloroplasts that is the site of electron transport and ATP synthesis.
A pyrimidine found in DNA that base-pairs with adenine.
A hormone synthesized from tyrosine in the thyroid gland.
A continuous network of protein strands around the circumference of epithelial cells, sealing the space between cells and forming a barrier between the apical and basolateral domains.
An enzyme that catalyzes the reversible breakage and rejoining of DNA strands.
A protein that regulates the activity of RNA polymerase.
The synthesis of an RNA molecule from a DNA template.
A regulatory mechanism that controls elongation of an mRNA molecule past a certain site on the DNA template.
The sorting and transport of proteins to different domains of the plasma membrane following endocytosis.
A G protein that stimulates cGMP phosphodiesterase when it is activated by rhodopsin.
The introduction of a foreign gene into eukaryotic cells.
RNA molecules that function as adaptors between amino acids and mRNA during protein synthesis.
A polypeptide growth factor that generally inhibits animal cell proliferation.
A mouse that carries foreign genes incorporated into the germ line.
The synthesis of a polypeptide chain from an mRNA template.
Integral membrane proteins that span the lipid bilayer and have portions exposed on both sides of the membrane.
See electron microscopy.
The movement of DNA sequences throughout the genome.
A DNA sequence that can move to different positions in the genome.
Three fatty acids linked to a glycerol molecule.
A cytoskeletal protein that polymerizes to form microtubules.
Any abnormal proliferation of cells.
A polypeptide growth factor that induces programmed cell death.
A compound that leads to tumor development by stimulating cell proliferation.
A virus capable of causing cancer in animals or humans.
The internal hydrostatic pressure within plant cells.
See coenzyme Q.
A highly conserved protein that acts as a marker to target other cellular proteins for rapid degradation.
The transport of a single molecule across a membrane.
A pyrimidine found in RNA that base-pairs with adenine.
A large membrane-enclosed sac in the cytoplasm of eukaryotic cells. In plant cells, vacuoles function to store nutrients and waste products, to degrade macromolecules, and to maintain turgor pressure.
A DNA molecule used to direct the replication of a cloned DNA fragment in a host cell.
A drug that inhibits microtubule polymerization.
A drug that inhibits microtubule polymerization.
See immunoblotting.
A method in which the diffraction pattern of X rays is used to determine the arrangement of individual atoms within a molecule.
An African clawed frog used as a model system for developmental biology.
A vector that can replicate as a chromosome in yeast cells and can accommodate very large DNA inserts (hundreds of kb).
The simplest unicellular eukaryotes. Yeasts are important models for studies of eukaryotic cells.
A species of small fish used for genetic studies of vertebrate development.
A type of DNA binding domain consisting of loops containing cysteine and histidine residues that bind zinc ions.
A fertilized egg.
The stage of meiosis I during which homologous chromosomes become closely associated.