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| 51177823 | adenylyl cyclase | An enzyme that converts ATP to cyclic AMP in response to a chemical signal. | |
| 51177824 | cyclic AMP (cAMP) | Cyclic adenosine monophosphate, a ring-shaped molecule made from ATP that is a common intracellular signaling molecule (second messenger) in eukaryotic cells (for example, in vertebrate endocrine cells). It is also a regulator of some bacterial operons. | |
| 51177825 | diacylglycerol (DAG) | A second messenger produced by the cleavage of a certain kind of phospholipid in the plasma membrane. | |
| 51177826 | G protein | A GTP-binding protein that relays signals from a plasma membrane signal receptor, known as a G-protein-linked receptor, to other signal transduction proteins inside the cell. When such a receptor is activated, it in turn activates the G protein, causing it to bind a molecule of GTP in place of GDP. Hydrolysis of the bound GTP to GDP inactivates the G protein. | |
| 51177827 | G-protein-linked receptor | A signal receptor protein in the plasma membrane that responds to the binding signal molecule by activating a G protein. | |
| 51177828 | hormone | In multicellular organisms, one of many types of circulating chemical signals that are formed in specialized cells, travel in body fluids, and act on specific target cells to change their functioning. | |
| 51177829 | inositol trisphosphate (IP3) | A second messenger that functions as an intermediate between certain nonsteroid hormones and a third messenger, a rise in cytoplasmic Ca2+ concentration. | |
| 51177830 | ligand | A molecule that binds specifically to a receptor site of another molecule. | |
| 51177831 | ligand-gated ion channel | A protein pore in the plasma membrane that opens or closes in response to a chemical signal, allowing or blocking the flow of specific ions. | |
| 51177832 | local regulator | A chemical messenger that influences cells in the vicinity. | |
| 51177833 | protein kinase | An enzyme that transfers phosphate groups from ATP to a protein. | |
| 51177834 | protein phosphatase | An enzyme that removes phosphate groups from proteins, often functioning to reverse the effect of a protein kinase. | |
| 51177835 | reception | In cellular communication, the target cell's detection (by binding to a receptor protein) of a signal molecule from outside the cell. | |
| 51177836 | receptor tyrosine kinase | A receptor protein in the plasma membrane that responds to the binding of a signal molecule by catalyzing the transfer of phosphate groups from ATP to tyrosines on the cytoplasmic side of the receptor. The phosphorylated tyrosines activate other signal transduction proteins within the cell. | |
| 51177837 | response | In cellular communication, the change in a specific cellular activity brought about by a transduced signal from outside the cell. | |
| 51177838 | scaffolding protein | A type of large relay protein to which several other relay proteins are simultaneously attached to increase the efficiency of signal transduction. | |
| 51177839 | second messenger | A small, nonprotein, water-soluble molecule or ion, such as calcium ion or cyclic AMP, that relays a signal to a cell's interior in response to a signal received by a signal receptor protein. | |
| 51177840 | signal transduction pathway | A mechanism linking a mechanical or chemical stimulus to a specific cellular response. | |
| 51177841 | transduction (1) | A DNA transfer process in which phages carry bacterial genes from one host cell to another. (2) In cellular communication, the conversion of a signal from outside the cell to a form that can bring about a specific cellular response. | |
| 51177842 | tyrosine kinase | An enzyme that catalyzes the transfer of phosphate groups from ATP to the amino acid tyrosine on a substrate protein. | |
| 51177843 | benign tumor | A mass of abnormal cells that remains at the site of origin. | |
| 51177844 | binary fission | The type of cell division by which prokaryotes reproduce. Each dividing daughter cell receives a copy of the single parental chromosome. | |
| 51177845 | cell plate | A double membrane across the midline of a dividing plant cell, between which the new cell wall forms during cytokinesis. | |
| 51177846 | centromere | The centralized region joining two sister chromatids. | |
| 51177847 | centrosome | Material present in the cytoplasm of all eukaryotic cells, important during cell division; the microtubule-organizing center. | |
| 51177848 | chromatin | The complex of DNA and proteins that makes up a eukaryotic chromosome. When the cell is not dividing, chromatin exists as a mass of very long, thin fibers that are not visible with a light microscope. | |
| 51177849 | cleavage furrow | The first sign of cleavage in an animal cell; a shallow groove in the cell surface near the old metaphase plate. | |
| 51177850 | cyclin | A regulatory protein whose concentration fluctuates cyclically. | |
| 51177851 | cytokinesis | The division of the cytoplasm to form two separate daughter cells immediately after mitosis. | |
| 51177852 | density-dependent inhibition | Referring to any characteristic that varies according to an increase in population density. | |
| 51177853 | gamete | A haploid cell, such as an egg or sperm. Gametes unite during sexual reproduction to produce a diploid zygote. | |
| 51177854 | genome | The complete complement of an organism's genes; an organism's genetic material. | |
| 51177855 | growth factor | A protein that must be present in the extracellular environment (culture medium or animal body) for the growth and normal development of certain types of cells; a local regulator that acts on nearby cells to stimulate cell proliferation and differentiation. | |
| 51177856 | kinetochore | A specialized region on the centromere that links each sister chromatid to the mitotic spindle. | |
| 51177857 | malignant tumor | A cancerous tumor that is invasive enough to impair the functions of one or more organs. | |
| 51177858 | metastasis | The spread of cancer cells to locations distant from their original site. | |
| 51177859 | origin of replication | Site where the replication of a DNA molecule begins. | |
| 51177860 | sister chromatids | Replicated forms of a chromosome joined together by the centromere and eventually separated during mitosis or meiosis II. | |
| 51177861 | somatic cell | Any cell in a multicellular organism except a sperm or egg cell. | |
| 51177862 | transformation | (1) The conversion of a normal animal cell to a cancerous cell. (2) A change in genotype and phenotype due to the assimilation of external DNA by a cell. | |
| 51177863 | tumor | a mass of abnormal cells that develop when cancerous cells divide and grow uncontrollably | |
| 51177864 | alternation of generations | A life cycle in which there is both a multicellular diploid form, the sporophyte, and a multicellular haploid form, the gametophyte; characteristic of plants. | |
| 51177865 | asexual reproduction | A type of reproduction involving only one parent that produces genetically identical offspring by budding or by the division of a single cell or the entire organism into two or more parts. | |
| 51177866 | autosome | A chromosome that is not directly involved in determining sex, as opposed to a sex chromosome. | |
| 51177867 | chiasmata | (plural, chiasmata) The X-shaped, microscopically visible region representing homologous chromatids that have exchanged genetic material through crossing over during meiosis. | |
| 51177868 | clone | A lineage of genetically identical individuals or cells. | |
| 51177869 | crossing over | The reciprocal exchange of genetic material between nonsister chromatids during prophase I of meiosis. | |
| 51177870 | diploid cell | A cell containing two sets of chromosomes (2n), one set inherited from each parent. | |
| 51177871 | fertilization | The union of haploid gametes to produce a diploid zygote. | |
| 51177872 | gamete | A haploid cell, such as an egg or sperm. Gametes unite during sexual reproduction to produce a diploid zygote. | |
| 51177873 | gene | A discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA (or RNA, in some viruses). | |
| 51177874 | genetics | The scientific study of heredity and hereditary variation. | |
| 51177875 | haploid cell | A cell containing only one set of chromosomes (n). | |
| 51177876 | homologous chromosome | Chromosome pairs of the same length, centromere position, and staining pattern that possess genes for the same characters at corresponding loci. One homologous chromosome is inherited from the organism's father, the other from the mother. | |
| 51177877 | karyotype | A display of the chromosome pairs of a cell arranged by size and shape. | |
| 51177878 | locus | (plural, loci) A specific place along the length of a chromosome where a given gene is located. | |
| 51177879 | recombinant chromosomes | A chromosome created when crossing over combines the DNA from two parents into a single chromosome. | |
| 51177880 | sex chromosomes | One of the pair of chromosomes responsible for determining the sex of an individual. | |
| 51177881 | sexual reproduction | A type of reproduction in which two parents give rise to offspring that have unique combinations of genes inherited from the gametes of the two parents. | |
| 51177882 | synapsis | The pairing of replicated homologous chromosomes during prophase I of meiosis. | |
| 51177883 | syngamy | fusing of an egg and sperm | |
| 51177884 | tetrad | A paired set of homologous chromosomes, each composed of two sister chromatids. Tetrads form during prophase I of meiosis. | |
| 51177885 | variation | Differences between members of the same species. | |
| 51177886 | Zygote | The diploid product of the union of haploid gametes in conception; a fertilized egg. |
