Main Discoveries In Genetics

Chromosomal Basis of Inheritance of Class 12

Main Discoveries In Genetics

  • Avery, Macleod and Mc Carty (1944) – Proved that DNA is genetic material and gave Biochemical nature of gene DNA).
  • Arber, Smith and Nathan – Discovered restriction endonucleases in bacteria which are widely used in genetic engineering.
  • Briggs and King – Performed transplantation experiments of frog and toad eggs and proved that developmental changes are determined by molecular changes in the nucleus. When the nucleus from young embryonic cell is transplanted into nucleated egg, the tadpole develops.
  • Bateson – Father of animal genetics, gave the terms allele, F1, F2, homozygous, heterozygous and genetics; applied Mendel’s law on animals. Along with Punnett, he gave coupling and repulsion theory for genes.
  • Bridges – Structural and numerical changes in chromosome; discovered nondisjunction of chromosomes and XXY condition in Drosophila ; genetic balance theory of sex determination.
  • Blakeslee (1937) – Induced polyploidy by using Colchicine ; Trisomy in Datura.
  • Beadle and Tatum – One gene one enzyme theory ; started biochemical genetics as a new branch ; reported Nurtitional mutants (Auxotrophs) in Neurospora crassa (Bread Pink Mould).
  • Camerarius – Sexual reproduction in plants.
  • Correns – Term factor for genes discovered, incomplete dominance in Mirabilis jalapa (4 o’clock), Cytoplasmic inheritance in 4 o’clock, term plasmagenes for extranuclear DNA that controls cytoplasmic inheritance; rediscovered Mendel’s law and summarised Mendel’s assumptions in the form of principles.
  • Cuenot – Lethal genes in mice.
  • Cairns – Isolated DNA from E. coli.
  • Dodge – Father of haploid/Neurospora genetics.
  • Delbruck, Luria and Hershey – Reproduction and mutations in viruses.
  • Hugo de Vries – Mutation theory of evolution, mutations in Oenothera lamarckiana (evening primrose) ; rediscovered Mendel’s law.
  • Darwin – Theory of Pangenesis, theory of evolution.
  • Fairchild – Developed first and successful plant hybrid called fairchild mule by crossing carnation and sweet william plants.
  • Fraenkel Conrat – Confirmed that RNA is genetic material in TMV (plant virus).
  • Garrod – Father of biochemical human genetics, discovered inborn errors of metabolism like Alkaptonuria ; established relationship between gene and metabolic function.
  • Gamow – Gave idea of triplet nature of genetic code ; term genetic code.
  • Gold Schmidt – Gene is a chemical rather than a physical unit ; gynandromorphs in Drosophila.
  • Harris and Watkins – Protoplast fusion.
  • Hoagland – Discovered tRNA.
  • Holley – Clover leaf model of tRNA for yeast alanine. It was having 77 nucleotides.
  • Henking – X body in sperm of some insects.
  • Hershey and Chase – Proved that DNA is the chemical which is hereditary by using bacteriophage. They also proved that specifity depends on DNA and not on proteins.
  • Jeffery – DNA finger printing.
  • Johannsen – Term gene, genotype, phenotype and pure line.
  • Jacob and Monod – Operon model for gene regulation ; concept of mRNA.
  • Jacob and Wollman – Episome in bacteria.
  • Kolreuter (1760) – Equal contribution of the two sexes in plants. Father of quantitative polygenic inheritance ; he was first to show that traits remain discrete and never blend.
  • Khorana – In vitro synthesis of gene by linking 77 nucleotide pairs to code for yeast alanine tRNA. Later on he synthesized a functional E. coli tRNA tyrosine glue by linking 207 base pairs ; decipher genetic code ; discovered DNA T4 ligase enzyme for linking DNA pieces.
  • Kornberg – In vitro synthesis of DNA but this DNA was ss. DNA polymerase I enzyme.
  • Lederberg and Hays – Plasmids in bacteria.
  • Lederberg and Tatum – Sexuality in bacteria.
  • Lederberg and Zinder – Transduction in bacteria.
  • Levene – Chemistry of DNA and gave tetranucleotide hypothesis.
  • Lal Ji Singh – DNA finger printing.
  • Morgan (1866-1945) – Father of experimental genetics, used Drosophila (banana, fruit fly, vinegar fly) as genetic material ; discovered sex linkage and criss cross inheritance ; genes are locted in the chromosomes.
  • Muller – Father of Actinobiology, effect of radiations/X–rays on Drosophila.
  • Miescher – Isolated nuclein from nuclei of WBC in pus cells. This nuclein was lateron found to be DNA.
  • Meselson and Stahl – Proved that DNA replicates in semiconservative manner by using density gradient centrifugation technique.
  • Mc Clung – X–bodies observed by Henking in insect sperms was identified as sex chromosome.
  • Nirenberg – In vitro synthesis of poly U mRNA ; Nirenberg and Mathaei discovered genetic code and proved experimentally that genetic code is triple in nature ; UUU was first codon deciphered by him.
  • Ochoa – in vitro synthesis of ribonucleotides and RNA ; RNA polymerase enzyme.
  • Paul Berg – Father of genetic engineering. He transplanted gene of SV 40 virus in E. coli and developed a hybrid organism.
  • Stern – Cytological proof of crossing over.
  • Sutton – Concept of gene.
  • Temin and Baltimore – Discovered reverse central dogma. (RNA ®DNA®RNA®Protein) RNA shows reverse transcription in retroviruses.
  • Taylor – Chromosomes replicate in semiconservative manner.
  • Weismann – Continuity of germ plasm theory.
  • Watson and Crick – Double helical molecular model of DNA.
  • Wilkins and Franklin – X–ray crystallography of DNA and showed that a molecule of DNA has 2 spirally coiled strands with a diameter of 20Å.
  • Wilson and Stevens – Chromosome theory of sex determination ; term X and Y chromosome for sex chromosomes.
  • Yanofsky – Modified one gene one enzyme theory to one cistron one polypeptide theory.
  • Bishop and Varmus – Got nobel prize for the discovery of oncogenes.
  • Barbara Mc Clintock – Jumping genes (Transposons) in Maize and got nobel prize.
  • Landsteiner (1900) – Blood groups A, B and O in man but inheritance of blood groups was shown by Bergestein.
  • Sutton and Boveri – Gene chromosome theory of inheritance.
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