NEET MOST IMPORTANT NCERT LINES: GENETICS 🧬
PRINCIPLES OF INHERITANCE & VARIATION
🔹Mendel's Timeline:
"Mendel conducted artificial pollination/cross pollination experiments using true-breeding pea lines for seven years (1856-1863)."
🔹 True-Breeding Lines:
"A true-breeding line is one that, having undergone continuous self-pollination, shows the stable trait inheritance and expression for several generations." (Note: He selected 14 true-breeding varieties).
🔹 Law of Segregation:
"The alleles do not show any blending and that both the characters are recovered as such in the F2 generation though one of these is not seen at the F1 stage."
🔹 Incomplete Dominance:
"The F2 phenotypic ratio changed from 3:1 to 1:2:1 (same as the genotypic ratio)."
🔹 ABO Blood Grouping:
"ABO blood groups are controlled by the I gene." / "Multiple alleles can be found only when population studies are made."
🔹 Chromosomal Separation:
"Sutton and Boveri argued that the pairing and separation of a pair of chromosomes would lead to the segregation of a pair of factors they carried."
🔹 Linkage vs Recombination:
"Morgan attributed this to the physical association or linkage of the two genes and coined the term linkage... and recombination to describe the generation of non-parental gene combinations."
🔹 Henking's Discovery:
"Henking (1891) traced a specific nuclear structure all through spermatogenesis... He called this body X-body but he could not explain its significance."
🔹 Sickle-Cell Anemia:
"This substitution of amino acid in the globin protein results due to the single base substitution at the sixth codon of the beta globin gene from GAG to GUG." (Glutamic acid to Valine).
🔹 Phenylketonuria:
"The affected individual lacks an enzyme that converts the amino acid phenylalanine into tyrosine." (Pleiotropy example).
PRINCIPLES OF INHERITANCE & VARIATION
🔹Mendel's Timeline:
"Mendel conducted artificial pollination/cross pollination experiments using true-breeding pea lines for seven years (1856-1863)."
🔹 True-Breeding Lines:
"A true-breeding line is one that, having undergone continuous self-pollination, shows the stable trait inheritance and expression for several generations." (Note: He selected 14 true-breeding varieties).
🔹 Law of Segregation:
"The alleles do not show any blending and that both the characters are recovered as such in the F2 generation though one of these is not seen at the F1 stage."
🔹 Incomplete Dominance:
"The F2 phenotypic ratio changed from 3:1 to 1:2:1 (same as the genotypic ratio)."
🔹 ABO Blood Grouping:
"ABO blood groups are controlled by the I gene." / "Multiple alleles can be found only when population studies are made."
🔹 Chromosomal Separation:
"Sutton and Boveri argued that the pairing and separation of a pair of chromosomes would lead to the segregation of a pair of factors they carried."
🔹 Linkage vs Recombination:
"Morgan attributed this to the physical association or linkage of the two genes and coined the term linkage... and recombination to describe the generation of non-parental gene combinations."
🔹 Henking's Discovery:
"Henking (1891) traced a specific nuclear structure all through spermatogenesis... He called this body X-body but he could not explain its significance."
🔹 Sickle-Cell Anemia:
"This substitution of amino acid in the globin protein results due to the single base substitution at the sixth codon of the beta globin gene from GAG to GUG." (Glutamic acid to Valine).
🔹 Phenylketonuria:
"The affected individual lacks an enzyme that converts the amino acid phenylalanine into tyrosine." (Pleiotropy example).
