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WGENETICSV Definitions 1. Gene: a heritable factor that controls a specific characteristic, or a section of DNA that codes for the formation of a polypeptide. 2. Allele: a specific form of a gene occupying the same gene locus or position as other alleles of that gene, but differing from other alleles by small variations in its base sequence. 3. Genome: the whole of the genetic information of an organism. OR It is a complete set of chromosomes where every gene and chromosome is represented singly as in a gamete. 4. Gene mutation: a change in the sequence of bases in a gene. 5. Diploid: a diploid nucleus contains two copies of each chromosome, in homologous pairs. 6. Haploid: a haploid nucleus contains one chromosome of each homologous pair. 7. Homologous chromosomes: a pair of chromosomes with the same genes but not necessarily the same alleles of those genes. 8. Somatic cell: a body cell that is not a gamete. 9. Karyogram: a diagram or photograph of the chromosomes from an organism. 10.Karyotype: the number and type of chromosomes present in a nucleus. 11.Recombination: In each homologous pair, one chromosome is a maternal chromosome and the other a paternal chromosome. After crossing over, the chromatids recombine to produce new and unique combinations of alleles, different from both the maternal and the paternal arrangements. This is called recombination. 12.Genotype: the alleles possessed by an organism each allele is represented by a letter; chromosomes come in pairs and so alleles come in pairs a genotype is therefore represented by a pair of letters, such as TT or Tt. PAGE 1|
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