SCIENCE - Genetics

• Inheritance


  The process of how a child receives genetic information from the parent
• The whole process of heredity is dependent upon inheritance, and it is the reason that the offsprings are similar to the parents</b>
• Gregor Mendel


  Father of Genetics
• Gregor Mendel


  • Austrian Monk, born in what is now Czech Republic in 1822
  • Studied Theology and was ordained priest Order St. Augustine
  • Went to the University of Vienna, where he studied botany and learned the Scientific Method
  • Worked with pure lines of peas for eight years
• Mendel published Experiments in Plant Hybridization, in which he established his three Principles of Inheritance


  1866
• Mendel was the first biologist to use Mathematics to explain his results - quantitatively
• Mendel predicted the concept of genes. That genes occur in pairs. That one gene of each pair is present in the gametes
• Why Mendel selected pea plant


  • The pea plant can be easily grown and maintained
  • They are naturally self-pollinating but can also be cross-pollinated
  • It is an annual plant, therefore, many generations can be studied within a short period of time
  • It has several contrasting characters
• Genome


  The entire set of genes in an organism
• Trait information


  Located within an organism's genes
• Genes


  A section of DNA that is passed from parent to child
• Alleles


  Two genes that occupy the same position on homologous chromosomes and that cover the same trait
• Dominant


  The allele of a gene that masks or suppresses the expression of an alternate allele; the trait appears in the heterozygous condition
• Recessive


  An allele that is masked by a dominant allele; does not appear in the heterozygous condition, only in homozygous
• Genotype


  The genetic makeup of an organisms
• Phenotype


  The physical appearance of an organism (Genotype + environment)
• Mendel's Experiments


  1. Monohybrid Cross

  2. Dihybrid Cross
• Mendel found that certain factors were always being transferred down to the offspring in a stable way. Those factors are now called genes
• Monohybrid Cross


  The hybrid of two individuals with homozygous genotypes which result in the opposite phenotype for a certain genetic trait
• Monohybrid cross is used by geneticists to observe how homozygous offspring express heterozygous genotypes inherited from their parents
• The genetic makeup of the plant is known as the genotype. On the contrary, the physical appearance of the plant is known as phenotype
• The genes are transferred from parents to the offspring in pairs known as alleles
• During gametogenesis when the chromosomes are halved, there is a 50% chance of one of the two alleles to fuse with the allele of the gamete of the other parent
• Homozygous alleles


  When the alleles are the same
• Heterozygous alleles


  When the alleles are different
• Law of Dominance


  Hybrid offspring will only inherit the dominant trait in the phenotype. The alleles that are suppressed are called the recessive traits while the alleles that determine the trait are known as the dominant traits
• Law of Segregation


  During the production of gametes, two copies of each hereditary factor segregate so that offspring acquire one factor from each parent
• Law of Independent Assortment

  A pair of traits segregates independently of another pair during gamete formation. As the individual heredity factors assort independently, different traits get equal opportunity to occur together