Dictionary,Defintion,Meaning,What is Donnan Equlibrium, Duodenum, DNA-Deoxyribonucleic Acid, Dogfish, Dominant, Dominant Species

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Home >>Biology Dictionary >> Donnan Equlibrium - Duodenum

	DNA (deoxyribonucleic acid) The genetic material of most living organisms, which is a major constituent of the chromosomes within the cell nucleus and plays a central role in the determination of hereditary characteristics by controlling protein synthesis in cells ( see also genetic code). DNA is a nucleic acid composed of two chains of nucleotides in which the sugar is deoxyribose and the bases are adenine, cytosine, guanine, and thymine (compare RNA). Dogfish. Any small cartilaginous fish of the family Scyllidac; a small shark. Dominant. Plant that, because of its foliage cover or extent of its root system, modifies and controls the local environment; usually many individuals constituting the dominant stratum. Dominant Species. The Commonest species in a community. Donnan equilibrium. An electrochemical equilibrium that is set up when two solutions are separated by membrane that is impermeable to some of the ions in solution.
Donor. An individual from whom blood or tissue is taken for transfer to another, e.g. in grafting; blood transfusion. Dopa. Dihyroxy phenylalanine, an intermediate substance in the production of adrenaline and noradrenaline, and also of melanin. Dopamine. The decarboxyylation product of Dopa. Formula: C₈H₁₁O₂N. Dormant. Alive but not growing; buds with an unbroken cover of scales; quiescent; inactive; a resting stage.
Dormin. Abscisic acid. Dorsal.(Zool). Situated at, or relatively nearer to, the back. Dorsal Fin. Any unpaired median fin on the backs of fishes and some other acquatic vertebrates. The fin maintains balance during locomotion. Dorsal Lip. Of blastopore. Part of rim of blastopore corresponding to future dorsal side, in amphibian embryo. Dorsal Root (Posterior R., Sensory R.) Never root of vertebrates containing the sensory fibres. The known amount of chemical or other treatment received by an organism. Double Fertilization. In angiosperms union of one male nucleus with egg nucleus to form zygote and of the other with primary endosperms nucleus to form endosperms nucleus. See Embryo sac.
Double recessive. An organism with two recessive alleles for a particular characterstic. Down. The soft small feathers backing BARBULES that cover the body of a bird and aid heat retention. Ductless Gland. Endocrine gland. Ductus Cuvieri (Cuvierian Duct). Main vein of fish (and of tetrapod embryo) returning blood from cardinal veins (in body-wall) to heart (under gut) in a fold of Coelomic lining which forms the posterior wall of pericardial cavity. There is one on each side. Becomes vena cava superior in adult tetrapods.
	Duodenum. First part of small intestine of vertebrates. Leads out of stomach, junction being guarded by pyloric sphincter. Secrets digestive enzymes from walls and receives bile and pancreatic ducts. A region of active digestion and absorption. Dura Mater. Firm connective tissue covering brain and spinal cord of vertebrates, containing blood – vessels. Dyad. Chromosome consisting of two sister CHROMATDS joined at their centromere which is produced after Disjunction. Dysplasia. Abnormal growth or development as may occur in organs or cells. Dysmenonrrhea. Menstruation.


Biology Dictionary - Part 3 Part 4 Gloycolysis - Gonad Hormones Grams Stain - Guttation Haemocoel - Hamulus Hemicelluloses - Hepaticae Hibernation - Histone Homogametic Sex - Hormone Hyostylic Jaw Suspension Hypoglossal Nerve - Hypotonic Immunity - Impulse Inflammation - Insectivore Interphase - Involucre, Isoptera Jeiunum - Junior Homonym Karyotype - Krebs Cycle Labium - Lectin Lethal Gene - Limnology Lomasome - Lymphocyte Macropterous - Mammary Glands Marsupium - Meiosis Menstrual Cycle - Microbodies Mid Brain,Mesencephalon - Mitogenetic Rays Molars - Morphactins Mycoplasms - Myriapoda

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