genbio

• Genetics


  The science that deals with the heredity and the factors that affect the transmission of traits from one generation to another
• Heredity


  The transmission of genetic materials from the parents to offspring
• Factors of heredity

  • Biological factor
  • Environment
  • Advanced technology
• Gene


  The factor that control the inheritance that is responsible for the transmission of traits
• Gregor Mendel


  • Augustinian monk in Brunn, Austria
  • Father of Classical Genetics
  • Formulated the Blending Theory of Inheritance (a discredited theory)
• Blending Theory of Inheritance suggests that the inheritance of traits from two parents produces offspring with characteristics that are intermediate between those of the parents
• When Mendel cross pollinated the tall pea plants and short pea plants

  The resulting offspring were either tall or short, not medium like what the blending theory of inheritance suggests

  
• Why Mendel chose the pea plants

  • Easy to cultivate
  • Perfect flower
  • Cross pollination can be done manually
  • Short generation time
  • With pair of contrasting traits
• Mendel's Experiment on Seven Contrasting Traits of Pea Plants
• Principle of Dominance


  In each organism, there is a pair of factors which controls the appearance of a particular trait. One member of the pair of factors may hide or prevent the appearance of the other factor.
• Dominant Trait


  Usually seen or expressed, symbolized by the capital letters
• Recessive Trait


  Usually hidden or not expressed, symbolized by small letters
• Homozygous (Pure-bred)


  The gene pairs are identical
• Homozygous Dominant


  The gene pairs are both dominant, symbolized by both capital letters
• Homozygous Recessive


  The gene pairs are both recessive, symbolized by both small letters
• Heterozygous (Hybrid)


  The gene pairs are not identical, symbolized by one capital letter and one small letter
• Alleles


  The alternative forms of genes
• Phenotype


  Physical appearance of an organism usually an adjective or words describing a trait
• Genotype


  The genetic make-up of an organism usually a letter symbolizing the trait of an organism
• Mendelian Inheritance is a set of primary principles relating to the transmission of hereditary characteristics from parent organisms to their children; it underlies much of genetics

  
• Mendel's Laws of Heredity or Mendelian inheritance were derived from his experiments on garden peas (Pisum sativum) between 1856 and 1863
• Mendel's Law of Segregation


  When two traits come together in one hybrid pair, the two characters do not mix with each other and are independent of each other. Each gamete receives one of the two alleles during meiosis of the chromosome.
• Mendel's law of segregations supports the phenotypic ratio of 3:1 i.e. the homozygous dominant and heterozygous offspring show dominant traits while the homozygous recessive shows the recessive trait
• The gametes have two versions of each chromosome: one contributed by the female parent in her ovum and one by the male parent in his sperm. These are joined at fertilization. The ovum and sperm cells (the gametes) have only one copy of each chromosome and are described as haploid
• Alleles


  Can be Dominant or Recessive
• Recessive traits are only visible if an individual inherits two copies of the recessive allele
• Mendel's Law of Dominance


  In a heterozygous condition, the allele whose characters are expressed over the other allele is called the dominant allele and the characters of this dominant allele are called dominant characters. The characters that appear in the F1 generation are called as dominant characters. The recessive characters appear in the F2 generation.
• Mendel's Law of Independent Assortment/ Dihybrid cross


  At the time of gamete formation, the two genes segregate independently of each other as well as of other traits.
• Dihybrid cross


  • Cross between two true-breeding parents that express different traits for two characteristics: green, wrinkled seeds (yyrr) and yellow, round seeds (YYRR)
• Reginald Punnett


  • Became interested in the experimental process during his stay at Cambridge
  • Began a scientific collaboration with William Bateson
  • They both published the first account of gene linkage in sweet peas and later developed the "Punnett square"
• Punnett Square


  A tool used to predict the possible breeding outcomes of two genes segregate independently of each other as well as of other traits

  
• Walter Sutton 


  coined the word “gene”
• THEODORE BOVERI


  found out that inherited trait is determined by chromosome
• CHROMOSOME THEORY OF INHERITANCE


  explained that gene in the chromosome is responsible for the transmission of traits
• CHROMOSOME


  located inside the cell’s nucleus containing the DNA
• Dominant Characters


  The characters that appear in the F1 generation
• Recessive Characters


  The characters that appear in the F2 generation
• Principles and Laws of Genetics


  also known as Mendelian Genetics