Introduction- keywords

• Gene


  A section of DNA that codes for the synthesis of a single polypeptide
• Locus


  The position of a gene on a chromosome
• Allele


  An alternative form of gene that occurs at the same locus on homologous chromosomes
• Mitosis


  A type of cell division where the daughter cells have the same number of chromosomes as the parent cell
• Meiosis


  A type of cell division where the chromosome number is halved
• Homologous chromosomes


  One of the different forms of a particular gene
• Chromatid


  One of the two copies of a chromosome that are joined together by a centromere prior to cell division
• Diploid


  A term referring to a nucleus which contains two pairs of chromosomes
• Genome


  Term used to denote the entire DNA sequence of a gamete, person, population or species
• Chromosome


  Rod-shaped structures within the cell nucleus that carry genes encoded by DNA
• Homozygous


  The situation in which the allelic genes are identitical
• Heterozygous


  The situation in which the allelic genes are different
• Recessive


  Genes are recessive if the phenotype they code for is only expressed when the genes are homozygous
• Dominant


  Gene where the trait will always appear or express itself; shown with a capital letter
• Genotype

  The genetic constitution of an organism
• Phenotype

  The expression of the genes and its interaction with the environment
• Codominant

  Both alleles are equally dominant and expressed in the phenotype
• Multiple alleles

  More than two alleles for a single gene
• Sex-linkage

  A gene whose locus is on the X chromosome
• Autosomal linkage

  Genes that are located on the same chromsome
• Epistasis

  When one gene modifies or masks the expression of a different gene at a different locus
• Monohybrid

  Genetic inheritance cross of a characteristic determined by one gene
• Dihybrid

  Genetic inheritance cross for a characteristic determined by two genes