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SCIENTISTS WHO

HAVE CONTRIBUTED TO

THE STUDY ANDDEVELOPMENT OF

MICROBIOLOGY AND

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C O O OG

A PRESENTATION BY

ANUPAMA. C.N08CBT4057

SJASC

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NUCLEIC

ACIDS

PART ONE

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Nucleic acids are complex macromolecules of immense biological importance present in allliving cells viruses.

  They control important biosynthetic activities of the cell and carry hereditary information fromgeneration to generation.

 There are two types of nucleic acids namely

Ø DNA (deoxyribose nucleic acids) and

Ø RNA (ribose nucleic acids).

INTRODUCTION

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Frederick Miescher (1868)was a Swiss

biochemist. He discovered thenucleic acid when hewas investigating the

action of pepsin onpus cells which hebravely collectedfrom the discarded

hospital bandages. The undigestedresidue compoundobtained from thenuclei of the pus cellswas named by him as

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Kossel then identifiedtwo types of purines- Adenine and Guanineand two types of pyramidines- Thymineand Cytosine . He wasawarded the NobelPrize in 1910 for thisdiscovery.

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A Russian biochemistnamed Levene recognized a five-

carbon ribose sugar  and phospheric acid innucleic acids.

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In 1947, Chargaff  

made a detailedchemical analysis of DNA.

He established theamount of Adenine isequivalent to theamount of Thymineand that of Guanine to

Cytosine. This is calledChargaff’s Law.

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In 1950, Wilkins 

found out the physical nature of DNA through X-ray diffraction

method.

In 1967 Kornberg synthesized theDNA in thelaboratory.

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In 1953, working at the Cambridge University,London, James. D. Watson and F.H.C Crick constructed the Double Helix model (Duplex) of 

DNA based on its physiochemical nature.

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Watson and Crick  proposed the semi-conservative

hypothesis of DNAreplication.

•  This wasexperimentally provedby Stahl andMeselson in 1958.

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After14

•In 1928FrederichGriffith 

conductedsomeexperiments toshow that themolecule of inheritance wasDNA.

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 These findings wereconfirmed by otherscientists namely 

Albert Hershey-Martha Chase,MacLeod and McCarthy through

experiments.

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 The Messenger RNA (mRNA)was first

discovered by Volkin in theE.coli'.

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Later in 1961 the term mRNA was coinedby Jacob and Monad.

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 The clover leaf model of theTransfer RNA (tRNA) was

proposed by Albert W Holley in 1964.

He shared the Nobel Prize withH.G.Khorana and

Nirenberg.

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MICROBIOLOGY

PART TWO

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Bacteria werefirst observedby Anton vanLeeuwenhoek 

in 1676 using asingle-lensmicroscope of 

his own design.

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 The name

"bacterium" wasintroduced muchlater, byChristianGottfriedEhrenberg in1828, derived

from the Greekword ‘βακτηριον’meaning "small

stick".

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While vanLeeuwenhoek isoften cited as thefirst microbiologist,

the first recordedmicrobiologicalobservation, that of the fruiting bodies of molds, was madeearlier in 1665 byRobert Hooke. He iscredited with beingthe first person to

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 The field of 

bacteriology (later asubdiscipline of microbiology) isgenerally considered

to have beenfounded byFerdinand Cohn(1828–1898).

Cohn was also thefirst to formulate ascheme for thetaxonomic

classification of 

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•Louise Pasteur(1822–1895) is mostfamous for his series

of experimentsdesigned to disprovethe then widely heldtheory of spontaneous

generation, therebysolidifyingmicrobiology’sidentity as a biologicalscience.

•Pasteur alsodesigned methods forfood preservation(pasteurization) and

vaccines againstseveral diseases such

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•Robert Koch (1843–1910) is best known forhis contributions to the

germ theory of disease,proving that specificdiseases were causedby specific pathogenicmicroorganisms.

•Koch was one of thefirst scientists to focuson the isolation of bacteria in pure culture

resulting in hisdescription of severalnovel bacteria includingMycobacteriumtuberculosis, the

causative agent of 

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•Martinus Beijerinck (1851–1931) made twomajor contributions to

microbiology: the discoveryof viruses and thedevelopment of enrichmentculture techniques.

•While his work on the Tobacco Mosaic Virus

established the basicprinciples of virology, it washis development of 

enrichment culturing thathad the most immediateimpact on microbiology byallowing for the cultivation

of a wide range of microbeswith wildl different

nogra s y

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nogra s y (1856–1953)was thefirst to develop theconcept of 

chemolithotrophyand to therebyreveal the essentialrole played bymicroorganisms ingeochemicalprocesses.

•

He was responsiblefor the first isolationand description of both nitrifying and

nitrogen-fixingbacteria.

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• The credit for theinvention of 

inoculation nowgoes to Edward Jenner who in 1796injected cowhand

 James Phipps withcowpox. Jennergets the creditbecause he carriedout his work usingaccepted scientificmethod and wrote it

up afterwards

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AlexanderFlemingdiscovered thepencillin.He was

awarded theNobel prize in1945 for thediscovery of 

 penicillin

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Paul Ehrlich contributed agreat deal toimmunology.In 1905 hewas awardedthe nobelprize for work 

in immunity 

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www.wikipedia.com

www.scirus.com

www.yahoo.com

www.google.com

www.nobleprize.com

www.scientistsworld.com

 Text book of biology-expert series

Microbiology-himalaya publications

BIBLIOGRAPHY