Different terminologies of genetics and related medical terms.pptx

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1. DEFINITION Allele : any one of two or more alternateforms of a gene at the same location. Anallele for each gene is inherited from eachparent . Autosome : a single chromosome from any ofthe 22 pairs of chromosomes not involvedin sex determination (XX or XY) Carrier: person who is heterozygous; possessing two different alleles of a gene pair Chromosome: microscopic structures in thecell nucleus that contain genetic information and are constant in number in aspecies ( eg , humans have 46 chromosomes) Deoxyribonucleic acid (DNA): the primarygenetic material in humans consisting ofnitrogenous bases, a sugar group, andphosphate combined into a double helix. Diploid: the number of chromosomes normally present in somatic cells. For humans, it is 46. Dominant: a genetic trait that is normallyexpressed when a person has a gene mutation on one of a pair of chromosomes andthe “normal” form of the gene is on theother chromosome Genetics : the scientific study of heredity;how specific traits or predispositions aretransmitted from parents to offspring Genome: the total genetic complement of anindividual genotype Genomics : the study of the human genome,including gene sequencing, mapping, andfunction Genotype : the genes and the variationstherein that a person inherits from his orher parents Haploid: the number of chromosomes present in egg or sperm (gametes); in humans,this is 23 Human Genome Project : an internationalresearch effort aimed at identifying andcharacterizing the order of every base inthe human genome

2. Haploid: the number of chromosomes present in egg or sperm (gametes); in humans,this is 23 Human Genome Project : an internationalresearch effort aimed at identifying andcharacterizing the order of every base inthe human genome Meiosis: the reduction division of diploidegg or sperm (germ cells) resulting inhaploid gametes (having 23 chromosomeseach ) Mitosis: cell division occurring in somatic cells that normally results in daughter cells with the same number of chromosomes— 46 (diploid). Monosomy : missing one of a chromosome pair in normally diploid cells (for example, 45,X females have only one X chromosome) Mutation: a heritable alteration in the genetic material Nondisjunction : the failure of a chromosome pair to separate appropriately during meiosis, resulting in abnormal chromosome numbers in reproductive cells (Gametes) or cells.

3. Nucleotide: a nucleic acid “building block” composed of a nitrogenous base, a five carbon sugar, and a phosphate group Pedigree : a diagrammatic representation of a family history Penetrance : the percentage of individual known to carry the gene for a trait who Actuallymanifest the condition. For example, a trait with 90% penetrance will not be manifested by 10% of persons possessing the gene. Phenotype: a person’s entire physical, biochemical, and physiological makeup, as determined by the individual’s genotype and environmental factors

4. Polymorphism : a genetic variation with two or more alleles that is maintained in a population Population screening : the application of a test or inquiry to a group to determine if individuals in the group have an increased likelihood of a genetic condition or a mutation in a specific gene (e.g., cholesterol screening for hypercholesterolemia) Predisposition testing: testing that is used to determine the likelihood that a healthy person with or without a family history of a condition will develop the disorder. Having the gene mutation would indicate that the person has an increased susceptibility to the disorder, but this is not a diagnosis. One example is DNA mutation testing for hereditary breast/ovarian cancer.