Pedigree

• Pedigree


  Diagrams showing the ancestral relationship and transmission of genetic traits over several generations in a family
• Proband


  The individual in the pedigree that led to the construction of the pedigree
• Law of Segregation (1st Mendelian Law)

  • For every trait governed by a pair of alleles, these alleles segregate or separate during gamete formation of meiosis
• Law of Independent Assortment (2nd Mendelian Law)


  • A pair of alleles for one trait will segregate or separate independently of another pair of alleles for another trait during meiosis
• Autosomal trait


  A trait whose alleles that control it are found in the autosomes (body chromosomes/ non-sex chromosomes)
• Genotype


  The gene pair an individual carries for a particular trait symbolized with a pair of letters
• Genotypes


  • Homozygous dominant with two dominant alleles (DD)
  • Heterozygous with a dominant and recessive allele (Dd)
  • Homozygous recessive with two recessive alleles(dd)
• Phenotype


  The observable trait of an individual based on its genotype
• Phenotypes


  • Dominant (requires at least one dominant allele)
  • Recessive (requires two recessive alleles)
• Phenocopy


  A trait that is expressed due to specific environmental conditions and is not due to the genotype
• Identical twins


  Monozygotic twins, derived from a single fertilization event
• Fraternal twins


  Twins derived from separate fertilization events, also known as dizygotic twins
• Genes


  The basic physical and functional unit of heredity, made up of DNA, some act as instructions to make proteins
• Alleles


  One of two or more versions of a gene with small differences in their sequence of DNA bases
• Zygote


  Fertilized egg cell that results from the union of a female gamete (egg, or ovum) with a male gamete (sperm)
• Gamete


  A mature haploid male or female germ cell which is able to unite with another of the opposite sex in sexual reproduction to form a zygote
• Blastomere


  A cell formed by a cleavage of a fertilized ovum
• Blastocyst


  A rapidly dividing ball of cells, the inner group will become the embryo and the outer group will become the cells that nourish and protect it
• Dominant allele


  Produces a dominant phenotype in individuals who have one copy of the allele, which can come from just one parent
• Recessive allele


  To produce a recessive phenotype, the individual must have two copies, one from each parent