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Definition
| A complete set of chromosomes. |
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Definition
| The genetic composition of an organism. |
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Definition
| The observable appearance of an organism. |
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Definition
| A strand of DNA found within the nucleus of a cell. |
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| Deoxyribonucleic acid (DNA) |
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Definition
| Molecules that compose chromosomes. |
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Definition
| A functional hereditary unit made up of DNA that occupies a fixed location on a chromosome. |
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Definition
| The translation of the genotype into the phenotype of an organism. |
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Definition
| Alternative version of a particular gene. |
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Definition
| Having two different alleles for a given gene. |
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Definition
| A gene that will produce its characteristic phenotype only when it occurs in a homozygous pair. |
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Definition
| A gene that produces its phenotype regardless of whether its paired allele is heterozygous or homozygous. |
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Definition
| A gene of which only the mother's or the father's copy is expressed, but not both in the normal Mendelian sense. |
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Definition
| A molecule that is similar to DNA that participates in the translation of genetic sequences into proteins. |
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Definition
| A sequence of three bases on the DNA molecule that encode one of 20 amino acids. |
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Definition
| The set of proteins encoded by the genome. |
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Definition
| Cell division in sexually reproducing organisms that reduces the number of chromosomes in half in the reproductive cells, such as sperm, eggs, and spores. |
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Definition
| The characteristic of genes located adjacent to one another to be passed along as a group. |
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Definition
| A process occurring during meiosis in which chromosomes exchange equivalent segments of DNA material. |
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Definition
| Having two identical alleles for a given gene. |
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Definition
| A heritable alteration of genes. |
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Term
| Sex-Linked Characteristics |
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Definition
| Phenotypical characteristics that result from expression of genes on the X chromosome that are not duplicated on the Y chromosome. |
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Term
| X Chromosome inactivation |
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Definition
| The process by which one X chromosome in each female cell is silenced to equalize the amount of proteins produced by males and females. |
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Term
| Single Nucleotide Polymorphism (SNP) |
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Definition
| Variation that occurs in a gene when a single base is changed from one version to the next. |
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Term
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Definition
| A degenerative, ultimately fatal condition marked initially by memory loss. |
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Definition
| The cell formed by the merged reproductive cells. |
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Definition
| An organism in its early stage of development; in humans, the developing individual is referred to as an embryo between two and eight weeks following conception. |
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Term
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Definition
| The unborn offspring; used to refer in humans to the developing individual following the embryonic stage until birth. |
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Definition
| One of the first three layers (endoderm, mesoderm, and ectoderm) that differentiate in the developing embryo. |
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Definition
| One of the initial three germ layers of the embryo, the source of skin and neural tissue. |
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Definition
| One of the initial three germ layers of the embryo that will form connective tissue such as ligaments, muscles, blood vessels, and the urogenital systems. |
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Definition
| One of the initial three germ layers of the embryo, the source of many internal organs. |
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Definition
| A layer formed by differentiating neural cells within the embryonic ectoderm. |
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Definition
| A chemical that produces cell differentiation. |
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Definition
| A structure formed by the developing embryonic neural plate that will eventually form the brain and spinal cord, with the interior of the tube forming the ventricle system of the adult brain. |
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Definition
| The layer of cells within the lining of the neural tube that will give rise to new neural cells. |
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Definition
| A stem cell in the ventricular layer that gives rise to either additional progenitor cells or migrating neural cells. |
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Definition
| The process of cell division that produces two identical daughter cells. |
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Definition
| Special glia that radiate from the ventricular layer to the outer edge of the cerebral cortex, serving as a pathway for migrating neurons. |
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Definition
| An embryonic mesodermic structure lying under the neural tube that will eventually develop into the spinal vertebrae. |
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Definition
| The swelling at the tip of a growing axon or dendrite that helps the branch reach its synaptic target. |
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Definition
| Long, fingerlike extensions from growth cones of axons and dendrites. |
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Definition
| Flat, sheetlike extensions from the core of growth cones of axons and dendrites. |
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Definition
| The process by which axons growing in the same direction stick together. |
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Term
| Cell adhesion molecule (CAM) |
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Definition
| A molecule on the surface of a growing axon that promotes fasciculation. |
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Definition
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Term
| Nerve Growth Factor (NGF) |
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Definition
| The first identified neurotrophin. |
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Definition
| Substance released by target cells that contributes to the survival of presynaptic neurons. |
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Definition
| A gene responsible for triggering the activity of caspases, leading to apoptosis. |
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Term
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Definition
| An enzyme within a cell that cuts up DNA and produces cell death. |
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Definition
| The process in which functional synapses are maintained and nonfunctional synapses are lost. |
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Definition
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Definition
| A segment of time during development in which a particular experience is influential and after which experience has little to no effect. |
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Term
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Definition
| A synapse strengthened by simultaneous activity; named after Donald Hebb. |
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Definition
| The process in which baby animals, particularly birds. learn to follow their mother immediately upon seeing her after birth or hatching. |
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Term
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Definition
| A neural tube defect in which the rostral neural tube does not develop normally, resulting in incomplete formation of the brain and skull. |
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Term
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Definition
| A neural tube defect in which the caudal part of the tube does not close properly. |
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Term
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Definition
| An abnormal genetic condition resulting from a genotype with three copies of chromosome 21, responsible for moderate mental retardation and a characteristic physical appearance. |
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Term
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Definition
| A heritable genetic disorder that produces cognitive and physical abnormalities. |
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Term
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Definition
| A heritable condition in which the individual does not produce enzymes necessary for the breakdown of phenylalanine; left untreated, the condition produces mental retardation. |
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Term
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Definition
| A set of physical and cognitive characteristics that result from maternal use of alcohol during pregnancy. |
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Term
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Definition
| The deterioration of the axon segment separated from the cell body by damage to the axon. |
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Term
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Definition
| The deterioration of the cell body and remaining axon stub produced by damage to an axon. |
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Term
| Transneuronal degeneration |
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Definition
| The deterioration of postsynaptic cells in response to loss of input from damaged presynaptic neurons. |
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Term
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Definition
| A substance that normally prevents further sprouting by mature axons. |
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Term
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Definition
| Deterioration of cognitive abilities resulting from brain disorders. |
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Definition
| The birth of new neural cells. |
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Term
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Definition
| An abnormal internal structure of neurons found in cases of Alzheimer's disease. |
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Term
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Definition
| An intracellular protein responsible for maintaining the structure of microtubules; broken down in conditions such as Alzheimer's disease. |
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Term
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Definition
| A protein associated with the degeneration of tissue, such as in patients with Alzheimer's disease and other types of dementia. |
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