Mendel's Laws of Inheritance: Segregation and Genotype-Phenotype Correlation - Prof. J. Si, Study notes of Biology

Download Mendel's Laws of Inheritance: Segregation and Genotype-Phenotype Correlation - Prof. J. Si and more Study notes Biology in PDF only on Docsity! Bio – March 15, 2012  Mendel’s First Law o The two members of a gene pair segregate (separate) from each other into the gametes o Each gamete carries one member of the gene pair  When does Mendelian segregation occur o When do homologous chromosomes separate? o Anaphase I of meiosis o Alleles segregate into different gametes  Genotype – Phenotype o Individual displaying a dominant trait may be homozygous or heterozygous  PP or Pp o Individual displaying a recessive trait MUST be homozygous for the recessive allele  pp  Test Cross (Fig 14.7) o How do you determine whether an individual is homozygous dominant or heterozygous? o Phenotype is P o Genotype is P- o Could be PP or Pp o Cross the individual with an unknown genotype with a homozygous recessive individual o Outcomes  If the individual with the unknown genotype is homozygous dominant  All offspring display the dominant trait  If the individual with the unknown genotype is heterozygous  Half the offspring display the dominant trait; half the offspring display the recessive trait  If the individual is homozygous recessive  All recessive  Incomplete dominance o Heterozygous individuals are intermediate between the dominant and recessive traits o Three phenotype o Ex. Carnations (red with white makes pink)  Codominance o Heterozygous individuals express traits of both alleles o Ex. Human ABO blood groups  Multiple alleles IA, IB, IO (i)  Phenotypes A, B, AB, O  IA is codominant with IB  IA is codominant to (i)  IB is codominant to (i)