Chromatid – definition

Chromatid Definition Chromatid is a replica of a CHROMOSOME that develops in preparation for cell division. Chromatids are “sister” pairs of each chromosome that contain identical genetic material. They remain attached to each other at the CENTROMERE until cell division. When the mother cell divides, the sister chromatids separate at the centromere and migrate into the new daughter cells, forming […]

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Stem Cell – what is, function and information

Stem Cell Definition Stem Cell – an undifferentiated, primal cell that has the capability to endlessly divide and develop into numerous types of cells.Totipotent stem cells exist primarily in the early EMBRYO (blastocyst) and can differentiate into (become) virtually any type of cell in the body. As the body becomes more complex and develops beyond […]

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Chromosome – what is, definition and function

Chromosome Definition A coiled DNA molecule within the cell’s nucleus that carries an individual’s GENETIC CODE. Most of the time the chromosome’s structure is loose and indistinguishable. Only in the stage of cell division immediately before the cell divides (the metaphase) does the chromosome draw itself into a compact, rodlike structure the geneticist can see under a microscope after […]

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Telomere – definition

Telomere Definition A structure of noncoding DNA (DNA that does not convey genetic instruction) at each end of a CHROMOSOME. Telomeres are essential for chromosome duplication during cell division. They function as handles to pull the chromatids (dividing chromosomes) apart as the mother cell divides into the two new daughter cells. The process of cell division permanently destroys a […]

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DNA – deoxyribonucleic acid – definition and function

Deoxyribonucleic Acid Definition DNA – the abbreviation for deoxyribonucleic acid. DNA is the molecule of heredity; its sequences form the body’s GENETIC CODE. Each cell in the body contains DNA within the chromosomes in its nucleus (except erythrocytes, which do not have nuclei). DNA has a characteristic double-helix structure that resembles a gently twisting ladder. The supporting […]

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Variation (genetic) – definition

Variation Definition The genetic differences among individuals. There are trillions of possible GENE combinations within the human GENOME. Except for identical twins, no two people share exactly the same GENOTYPE (genetic constitution). Though any two individuals may have 99.9 percent of the same DNA sequences and gene pairings, the 0.1 percent of pairings that differ accounts for the endless details that make each […]

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Gamete – definition

Gamete Definition Gamete is a spermatozoon (SPERM cell) or an ovum (egg cell). A gamete, also called a germ cell or sex cell, is a haploid cell; it contains half the complement of chromosomes and genetic material necessary to encode (result in creating) an individual. When two gametes merge they produce a single diploid cell, the ZYGOTE, […]

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Zygote – (genetic) definition

Zygote Definition The fertilized ovum (egg) before it begins to divide. The spermatozoon (SPERM cell) and the ovum are each haploid cells (gametes); they contain half the complement of chromosomes necessary to create an organism. When two gametes join they form a single diploid cell that contains the full complement of chromosomes. The zygote then divides as […]

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Gene – what is, definition and function

Gene Definition A segment of coding DNA (DNA that instructs the structure and function of cells throughout the body) composed of a specific sequence of nucleotides. The gene is the basic unit of inheritance that directs every facet of the body’s appearance and functions. Genes align along chromosomes in pairs. Each CHROMOSOME (AUTOSOME) contains thousands of genes, except the sex […]

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Genetic Carrier – definition

Genetic Carrier Definition Genetic Carrier – an individual whose GENOTYPE contains a recessive GENE MUTATION capable of causing a genetic disorder though the individual does not have or show symptoms of the disorder the mutation causes. Typically a genetic carrier has one “good” gene and one mutated gene. A genetic carrier may pass on the mutated gene to his or her […]

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