Genetics

• Genetics is the study of heredity and variation
• Genes

   sequences of nucleotides in DNA that serve as the basic physical and functional traits of heredity
• Heredity

  study of the passing of characteristics or traits through combined genetic materials of the parents to their children
• Variation

  any difference between the individuals in a species or groups of organisms
• variation


  due to different alleles
• alleles

  one of two or more versions of the DNA sequence
• alleles


  Usually have 2 alleles per gene
• genotype

  genetic makeup, or the combination of alleles represented by letters that correspond to specific alleles
• phenotype


   observable characteristics of an organism resulting from its genotype
• dominant


  traits are always expressed, even if only one copy of the dominant trait exists
• recessive


  traits are expressed only if both the connected alleles are recessive
• punnett square

  a simple graphical representation used in genetics to predict the possible outcomes of a cross between two individuals or organisms
• reginald punnett


  who developed the punnett square
• early 20th century


  when did reginald punnett develop the punnett square
• punnett square

  • fundamental tool in understanding basic principles of heredity
• Gregor Johann Mendel

  • Biologist, meteorologist, mathematician, augustinian friar, and abbot of St. Thomas’ Abbey in Brno (Brunn), Margraviate of Moravia
• Gregor Johann Mendel


  father of genetics
• Gregor Johann Mendel


  proposed the fundamental laws of inheritance
• • Segregation, Independent Assortment, Dominance


  what are the 3 laws in inheritance
• pisum sativum


  common pea
• 1822-1884


  year of birth and death of mendel
• selection of pea plants

  Mendel chose peas because they were easy to grow, had several easily observable traits with distinct variations, and had a short reproductive cycle.
• cross-pollination

  To control the breeding process, Mendel manually transferred pollen from the stamen of one pea plant to the pistil of another. This allowed him to ensure specific parentage in his experiments.
• study of traits

  Mendel focused on several easily distinguishable traits in pea plants.
• allele


  one of several possible forms of gene
• gene


  sequence of deoxyribonucleic acid that serves as the basic physical and functional traits of heredity
• seed shape, seed color, pod shape, pod color, flower color, flower/pod location, plant size


  what are the traits of a pea plant
• generation of purebred lines

  Mendel first created purebred lines (first filial generation, or F1) of pea plants for each trait by self-fertilizing plants with identical traits for several generations. This ensured that all offspring would display the same traits as the parent.
• true breeders/homozygous

  • the organism has two identical alleles of a particular trait.
• crossbreeding experiments

  Mendel then crossed purebred plants (F1) with different traits. For example, he would cross a tall plant with a short plant or a plant with yellow seeds with one with green seeds. (The offspring are the second filial generation or F2)
• hybrid/heterozygous


  offspring produced by crossbreeding
• hybrid/heterozygous


  The pair of alleles differs because they came from parents with different traits
• segregation


  Each individual possesses two alleles for each trait, one inherited from each parent.
• law of independent assortment

  • inheritance of one trait does not influence the inheritance of another trait
• dominance

  • An offspring that was developed from the crossbreeding of two parents, with each having true, different traits, will express the dominant trait and hide the recessive trait.
• independent assortment

  • that alleles of different genes assort independently during gamete formation
• segregation

  • These alleles segregate (separate) during gamete formation so that each gamete receives only one allele for each trait.
• independent assortment

  • directly leads to the diversity in characteristics
• segregation


  During fertilization, the offspring receives one allele for each trait from each parent, resulting in the formation of a genotype