Life Sciences Glossary: From Diabetes Mellitus to Dysgenic and Dominance

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Diabetes Mellitus

A complex disorder of carbohydrate, fat and protein metabolism due to relative or complete lack of insulin secretion by the beta cells of pancreas.

Diagnosis

Recognition of disease from symptoms.

Dyskinesia

The final stage of the first meiotic prophase.

Dialysis

The process of separating colloids and crystalline substances in solution by the difference in their rate of diffusion through a semipermeable membrane.

Diapause

A period of arrested development in the life cycle of insects.

Diapedesis

The passage of WBCs through intact blood vessel walls like amoeba.

Diaphragm

A dome – shaped partition that separates the thoracic and abdominal cavities in mammals.

Diaphysis

The shaft of a long bone.

Diarrheas

The frequent passage of loose, watery stools, generally the result of increased motility in the colon.

Distend

A natural toothless space between two types of teeth in a mammal.

Diastole

The relaxing dilation period of the heart muscle, especially of the ventricles.

Dictyosome

A stack of cisternae that forms part of the Golgi apparatus. In plant cells, the term is often used for the entire Golgi body.

Dicumarol

An anticoagulant used for the treatment of thrombosis.

Diet

The food and drinks items consumed by a person from day to day.

Differentiation

Changes that occur in the structure and function of cells and tissues as the development of the organism proceeds.

Diffusion

The movement of particles or molecules from the area of higher concentration, to an area of lower concentration.

Digitigrade

Walking on the digits with posterior part of the foot raised.

Dihydric

An individual heterozygous for two pairs of alleles, for example AOA Bb.

Dimorphism

Existence within a species of two distinct forms.

Dioeciously

Individuals producing either sperm or egg but not both.

Diphyodont

The development of teeth in two successive sets as in most mammals.

Diploblastic

Organism with two germ layers, ectoderm and endoderm.

Diploid

An individual or cell having two complete sets of chromosomes.

Diplopia

Double vision caused by defective function of the extra ocular muscles.

Dilutee

The stage of meiosis I during which homologues chromosomes separate along their length but remain associated at chiasmata.

Disjunction

The separation of homologous chromosomes during anaphase I of meiosis.

Distal

Away from or being the farthest from a point of origin.

Diuretic

Any agent that increases the secretion or lack of absorption of urine.

Diurnal

A life- style characterized by activity during the day rather than at night.

Divergent Evolution

A basic evolutionary pattern (opposite- nocturnal) in which individual speciation events cause many branches in the evolution of a group of organisms.

Dorsal

Towards the back, or upper surface of an animal.

Drones

Male bees which develop by parthenogenesis, i.e.. from unfertilized eggs.

Dropsy

An abnormal accumulation of clear, watery fluid in a body tissue or cavity, such as in a joint, the abdomen, the middle ear or in the gall- bladder.

Duodenum

The first part of the small intestine, which receives food from the stomach and secretions from the liver and pancreas.

Duplication

A chromosomal aberration in which a segment of the chromosome bearing specific loci is repeated.

Delamater

The outer membrane covering the brain and spinal cord.

Dyad

One of the groups of two chromosomes formed by the division of a tetrad during the first meiotic division.

Dysfunction

Absence of complete normal function.

Dysgenic

Any effect that is harmful to the genetics of future generation.

Dominance

The phenotypic expression of the individual effects of two different alleles in a heterozygote.

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