Mendelian

• Trait


  Any characteristic that can be passed from parent to offspring
• Heredity


  Passing of traits from parent to offspring
• Genetics


  Study of heredity
• Monohybrid cross


  Cross involving a single trait e.g. flower color
• Dihybrid cross


  Cross involving two traits e.g. flower color & plant height
• Alleles


  Two forms of a gene (dominant & recessive)
• Dominant


  Stronger of two genes expressed in the hybrid; represented by a capital letter (R)
• Recessive


  Gene that shows up less often in a cross; represented by a lowercase letter (r)
• Homozygous genotype


  Gene combination involving 2 dominant or 2 recessive genes (e.g. RR or rr); also called pure
• Heterozygous genotype


  Gene combination of one dominant & one recessive allele (e.g. Rr); also called hybrid
• Genotype


  Gene combination for a trait (e.g. RR, Rr, rr)
• Phenotype


  The physical feature resulting from a genotype (e.g. red, white)
• Gregor Mendel (1822-1884) was responsible for the Laws governing Inheritance of Traits
• Law of Dominance


  In every organism, there is a pair of factors or genes which control the appearance of a particular trait. One of the pair of genes/alleles may hide or prevent the appearance of the other. One allele is a dominant trait, while the other is a recessive trait. The dominant traits hide or mask the appearance of the recessive trait. The dominant trait is represented by a big letter and a small letter for the recessive trait.
• Law of Segregation


  All pairs of genes for all the traits of an organism segregate or separate from each other during meiosis or gametes (sex cells) formation. Gregor Mendel argued that for any trait, an organism must inherit one factor from the sperm and one factor from the egg. Thus, a new organism receives one factor for each trait from each parent.
• Law of Independent Assortment


  The distribution or assortment of one pair of genes is independent of the distribution of the other pair. Traits are inherited independent of each other. The law applies to genes that are found on separate chromosomes. Thus, one pair of genes is not affected by the other pair.
• Punnett Square


  Reginald C. Punnett is the one who devised the Punnett square.