Chapter 10 Definitions Essays - Cytogenetics, Chromosomes, Genetics

Chapter 10 Definitions autosome: any chromosome other than the sex chromosome base deletion: a mutation in which a nucleotide is lost from the DNA sequence base insertion: a mutation in which a nucleotide base is added to the DNA sequence carrier: an individual who is heterozygous for a recessive trait chromosome mapping: a method of determining the relative position of genes on a chromosome using information on crossover frequency crossing over: exchange of parts between two homologous chromosomes deletion: a mutation in which a chromosomal piece breaks off and is lost frame-shift mutation: a mutation in which a base deletion or insertion cause the gene's message to be translated incorrectly incomplete linkage: the breaking apart of genes in the same linkage group through crossing over of chromosomal material inversion: a mutation in which a segment of DNA in a chromosome flips upside down, but remains in place linkage group: genes that occur together on the same chromosome monosomy: the condition of missing a chromosome mutagen: any agent that increases the rate of mutation mutation: a change in the genetic material that results from an error in the replication of DNA nondisjunction: the failure of homologous chromosomes to segregate during meiosis point mutation: a mutation in which one base replaces another in the DNA chain polyploid: a condition of having extra sets of chromosomes red-green color blindness: the inability to distinguish red from green sex chromosome: one pair of chromosomes related to the sex of an individual sex-linked gene: a gene located on or linked to the sex chromosome sex-linked trait: a characteristic determined by genes on the X chromosome translocation: a mutation in which a chromosomal piece becomes attached to another chromosome trisomy: the condition of having an extra chromosome Chapter 11 Definitions genetic marker: a known DNA sequence that lies close to a disease causing gene, indicating the presence of this gene hemoglobin: a protein in red blood cells responsible for oxygen transport. hemophilia: a sex-linked disorder in humans in which blood cannot clot Huntington disease: a fatal genetic disorder caused by a dominant gene, the symptoms of the disease being loss of muscle co-ordination and mental deterioration karyotype: a photograph of a cells chromosomes, arranged in order from largest to smallest Klinefelter syndrome: a condition in males that includes abnormal sexual development resulting from the presence of an extra X chromosome melanin: a dark pigment multiple allele: three or more different alleles for a giver trait pedigree: a diagram showing how a trait is inherited in the family phenylketonuria (PKU): a genetic disease in which the absence of an enzyme causes a build-up of the amino acid phenylalanine causing severe retardation polygenic inheritance: a condition in which characteristics are governed by more than one gene sex-influenced trait: characteristic that is dominant in one sex and recessive in the other sex-limited gene: a gene that is expressed only in the individuals of a certain sex sickle-cell disease: a hereditary disease in which hemoglobin is abnormal and red blood cells are sickle shaped sickle cell trait: the condition of being heterozygous for sickle-cell disease syndrome: a group of symptoms with a single underlying cause Turner syndrome: a condition in females that includes abnormal sexual development, resulting from the absence of the X chromosome ultrasound: a technique using sound waves to locate and view a fetus in the uterus