Biotechnology and Genetics terms starting with H

178 terms

  1. homeodomain See: homeobox.
  2. homeotic genes Genes that act in concert to determine fundamental patterns of development.
  3. homeotic mutation A mutation that causes a body part to develop in an inappropriate position in an organism, such as the mutation in Drosophila melanogaster that causes…
  4. homoallele One of a number of otherwise identical alleles which differ at the same site in their sequence.
  5. homodimer A protein comprising two identical polypeptide chains, or a dimer of identical residues.
  6. homoduplex DNA A double-stranded fully complementary DNA molecule.
  7. homoeologous Referring to chromosome s which are descended from a common progenitor, but which have evolved to be no longer fully homologous.
  8. homogametic Producing similar gametes with regard to the sex chromosomes . In mammals, the female is homogametic (XX), and the male is heterogametic (XY).
  9. homogenotization An allele replacement technique, in which a bacterial cell is transformed with a plasmid containing an altered copy of the target sequence, and a double…
  10. homokaryon A cell with two or more identical nuclei as a result of fusion. Opposite: heterokaryon.
  11. Homolog In diploid organisms, one member of a pair of matching chromosomes.
  12. Homologous 1. General definition: from the same source, or having the same evolutionary function or structure. 2.
  13. Homologous chromosome Chromosome containing the same linear gene sequences as another, each derived from one parent.
  14. Homologous chromosomes Chromosomes that have the same linear arrangement of genes--a pair of matching chromosomes in a diploid organism. See Chromosomes.
  15. Homologous recombination The exchange of DNA fragments between two DNA molecules or chromatids of paired chromosomes (during crossing over) at the site of identical nucleotide…
  16. Homology 1. The degree of identity between individuals, or characters. 2. The degree of identity of sequence (nucleotide or amino acid) between a number of DNA or…
  17. homomultimer A protein consisting of a number of identical subunits.
  18. homoplasmy The condition in which all copies of an organelle in a cell are genetically identical. Opposite: heteroplasmy.
  19. homopolymer A polymer (nucleic acid, polypeptide, etc.) which contains only one kind of residue (e.g. the polynucleotide GGGGGGGGG...).
  20. homopolymeric tailing See: tailing.
  21. Homozygote An organism whose genotype is characterized by two identical alleles of a gene. See Allele, Genotype.
  22. homozygous (adj.) See: homozygote.
  23. Horizontal gene transfer Transmission of DNA between species, involving close contact between the donor's DNA and the recipient, uptake of DNA by the recipient, and stable…
  24. hormone (HOR-mone) One of many chemicals made by glands in the body. Hormones circulate in the bloodstream and control the actions of certain cells or organs.
  25. host In a network, the central computer which controls the remote computers and holds the central databases.
  26. host-specific toxin A metabolite, produced by a pathogen, and which is responsible for the adverse effects of the pathogen.
  27. hot spot See: recombinational hot spot.
  28. Hox genes Consists of at least 38 encoded nucleotides that contain genes found in four clusters on four different chromosomes.
  29. HSA See: serum albumin.
  30. HSC markers Cell-surface molecules that are used to identify hematopoietic stem cells.
  31. HSP One of a group of proteins that help protect cells from stresses such as heat, cold, and low amounts of oxygen or glucose (sugar).
  32. human artificial chromosome (Abbreviation: HAC). Analogous to yeast artificial chromosome, a construct comprising a human centromere and telomeres, which would allow for the cloning…
  33. Human artificial chromosome (HAC) A vector used to transfer or express large fragments of human DNA. HACs behave and are constructed like human chromosomes. See also chromosome, vector
  34. Human embryonic stem cell A stem cell that is derived from the inner cell mass of a blastocyst and can differentiate into several tissue types in a dish.
  35. Human embryonic stem cell (hESC) A type of pluripotent stem cell derived from the inner cell mass (ICM) of the blastocyst.
  36. Human gene therapy See: gene therapy
  37. Human Genome Initiative Collective name for several projects begun in 1986 by DOE to create an ordered set of DNA segments from known chromosomal locations, develop new…
  38. Human Genome Project An international research project to map each human gene and to completely sequence human DNA. See also gene, mapping
  39. Human Genome Project (HGP) Formerly titled Human Genome Initiative. See also: Human Genome Initiative
  40. human growth hormone (Abbreviation: hGH). See: growth hormone.
  41. Human growth hormone (HGH, somatotrophin) A protein produced in the pituitary gland that stimulates the liver to produce somatomedins, which stimulate growth of bone and muscle.
  42. human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) AIDS was first reported in 1981 in the United States and has since become a major epidemic, killing nearly 12 million people and infecting more than 30…
  43. Human Leukocyte Antigen (HLA) A distinguishing series of proteins that exist on the surface of every white blood cell to help the cells discriminate between "friendly" cells and…
  44. human-leukocyte-antigen system (Abbreviation: HLA). See: major histocompatibility antigens.
  45. humoral immune response See: antibody-mediated immune response.
  46. Huntington's disease A degenerative brain disorder that usually appears in mid-life. Its symptoms, which include involuntary movement of the face and limbs, mood swings, and…
  47. Hup+ Abbreviation for hydrogen-uptake positive.
  48. Hurler syndrome A heritable condition involving deficiency of an enzyme (alpha-L-iduronidase), leading to abnormal accumulations of materials inside cells, then resulting…
  49. Hybrid A class that is a mixture or combination of 2 or more classes. For example, a Druid can be viewed as a Warrior/Rogue/Priest hybrid.
  50. hybrid arrested translation A method used to identify what protein (s) are encoded by a particular cloned DNA sequence.
  51. hybrid cell See: synkaryon.
  52. hybrid dysgenesis Infertility and an increased incidence of chromosome mutations thought to be caused by the activation of transposons.
  53. hybrid released translation A method used to identify the gene product of a cloned gene. The cloned DNA is immobilized and hybridized with a mixed mRNA sample, so that only mRNA…
  54. hybrid seed 1. Seed produced by crossing genetically dissimilar parents. 2. In plant breeding, used colloquially for seed produced by specific crosses of selected…
  55. hybrid selection The process of choosing individuals possessing desired characteristics from among a hybrid population.
  56. hybrid vigour The extent to which a hybrid individual outperforms both its parents with respect to one or many traits.
  57. Hybridization The hydrogen bonding of complementary DNA and/or RNA sequences to form a duplex molecule. (See Northern hybridization, Southern hybridization.)
  58. Hybridoma A hybrid cell, composed of a B Iymphocyte fused to a tumor cell, which grows indefinitely in tissue culture and is selected for the secretion of a…
  59. Hydrogen bond A relatively weak bond formed between a hydrogen atom (which is covalently bound to a nitrogen or oxygen atom) and a nitrogen or oxygen with an unshared…
  60. hydrogen-uptake positive (Abbreviation: Hup+). A term describing a micro-organism that is capable of assimilating (or taking up) hydrogen gas.
  61. Hydrolysis A chemical reaction that uses water to break down a compound.
  62. hydrophobic interaction An interaction between a hydrophobic ('water-hating') part of a molecule and an aqueous environment.
  63. hydroponics The growing of plants without soil. Plants are fed with an aerated solution of nutrients, and the roots are either supported within an inert matrix, or…
  64. Hydroxyapatite A natural mineral structure that contains calcium and phosphate ions that provide the power for the formation of bones and teeth.
  65. hygromycin An antibiotic used as selective agent in bacterial and transgenic plant cell cultures.
  66. hyperploid The situation in which a particular chromosome or chromosome segment is present in more than the normal number. Opposite: hypoploid.
  67. hypersensitive response 1. A specific reaction of a plant to attack by a pathogen. The plant cells surrounding the point of infection rapidly die and dry out, so that pathogen…
  68. hypersensitive site Regions in the DNA that are highly susceptible to digestion with restriction endonucleases.
  69. hypertonic A solution with an osmotic potential greater than that of living cells. Treatment with such solutions leads to the plasmolysis of cells.
  70. hypervariable region The parts of both the heavy and light chains of an antibody molecule that enable it to bind to a specific site on an antigen.
  71. hypervariable segment A region of a protein that varies considerably between strains or individuals.
  72. Hypoblast The inner cell layer, or endoderm, which develops during the formation of the embryonic germ layers.
  73. hypocotyl The portion of an embryo or seedling below the cotyledons . A transitional area between stem and root.
  74. hypomorph A mutation that reduces, but does not completely abolish gene expression.
  75. hypoplastic Defective and reduced growth or development (e.g. dwarfing and stunting in plants) resulting from an abnormal condition, for example disease or…
  76. hypoploid The situation in which a particular chromosome or chromosome segment is present in less than the normal number. Opposite: hyperploid.
  77. hypothalamic peptides Peptides generated in the vertebrate forebrain and concerned with regulating the body's physiological state.
  78. hypotonic Osmotic potential less than that of living cells. Cells placed in a hypotonic solution will absorb water and display swelling and turgidity.