The EpiGeneSys Network of Excellence has either reviewed or contributed much of the Epigenetics and Epigenomic material on Wikipedia. Glossary links open a new window containing the relevant Wikipedia entry. Note that Wikipedia information can be altered by anyone and inaccuracies may occur. Wikipedia logo used with permission.
Response written by: Elphège Nora, PhD - postdoctoral researcher in Edith Heard's laboratory, Institut Curie
Each cell of the body produces molecules known as proteins. The structure of proteins...
Read more...Response written by: Elphège Nora, PhD - postdoctoral researcher in Edith Heard's laboratory, Institut Curie
Germ cells of human beings (and all other organism actually) are unfortunately unable...
Read more...| Term | Definition |
|---|---|
| Haemoglobin |
Oxygen-carrying protein found in the red blood cells of vertebrates and some invertebrates, made up from four subunits.
|
| Haemopoietic |
(haematopoietic) The formation of blood cellular components. This process occurs in myeloid tissue, which is found in the bone marrow and lymphatic tissue, such as lymph nodes or the spleen. All of the cellular components of the blood are derived from haematopoietic stem cells.
|
| Heterochromatin |
A type of chromatin that is darkly staining and tightly packaged or coiled throughout the cell cycle and that is, for the most part, genetically inactive.
|
| Histone |
The chief proteins of chromatin that act as spools around which DNA winds; they play a role in gene regulation.
|
| Histone acetylation |
See histone acetytransferase.
|
| Histone acetyltransferase |
An enzyme that acetylates conserved lysine amino acids on histone proteins.
|
| Histone code |
Theory that proposes that specific histone-tail modifications effected by enzymes, control the activity of genes in the nucleus, by providing binding sites for regulatory proteins.
|
| Histone deacetylase |
HDACs are enzymes that remove acetyl groups from histone proteins. This has the general effect of increasing the positive charge of histones and increasing their attraction for the negatively charged phosphate groups in DNA (see heterochromatin).
|
| Histone methylation |
Modification of the primary protein sequence of a histone protein by the addition of one, two, or three methyl groups. This modification alters the properties of the nucleosome and affects its interactions with other proteins. Specific kinds of methylation, e.g. methylation of lysine 9 within the histone H3 molecule are associated with inactive chromatin (see heterochromatin) where genes are relatively inactive.
|
| Histone methyltransferase |
(HMT) Enzymes that catalyze the transfer of methyl groups from certain types of histone proteins.
|
| Histone modification |
Acetylation, methylation, poly(ADP-ribose)ylation, phosphorylation, ubiquitylation of specific-amino-acid residues on histones, which are believed to control chromatin states.
|
| Homeostasis |
Encompasses physiological processes that allow an organism to maintain internal equilibrium.
|
| Homeotic (homeobox, hox) genes |
Homeotic genes in general transform parts of the body into structures appropriate to other positions. Genes with a homeobox or Hox domain involved in embryonic development in many organisms from fruit flies to humans.
|
| Homologue |
Describes a gene, protein or morphological structure that is similar in both DNA sequence and amino-acid sequence and function between organisms of different species. Real homologies are based on a common evolutionary descent in contrast to convergent evolution or analogies. Genes discovered initially in fruit flies often have homologues in mammals.
|
| Housekeeping gene |
Genes required throughout development for the smooth running of the cell's metabolism. Such genes are expressed continuously.
|