Griffith's experiment: Difference between revisions
imported>Tenshi Hinanawi Reverting edit(s) by 2A00:23C5:B1A:9E01:B96E:F73A:3F6E:FBDF (talk) to rev. 1270770345 by PrinceTortoise: Non-constructive edit (UV 0.1.6) |
imported>Mr.SGz m corrected name of the bacteria from diplococcus pneumoniae to streptococcus pneumoniae |
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'''Griffith's experiment''',<ref>{{Cite book|url=http://dx.doi.org/10.21428/cdd5dd5a|title=Experiment|publisher=PubPub|doi=10.21428/cdd5dd5a}}</ref> performed by [[Frederick Griffith]] and reported in 1928,<ref>{{cite journal |last=Griffith|first=Fred.|author-link=Frederick Griffith|title=The Significance of Pneumococcal Types|journal=Journal of Hygiene |publisher=Cambridge University Press|date=January 1928|volume=27|issue=2|pages=113–159|jstor=4626734 |pmid=20474956 |pmc=2167760 |doi=10.1017/S0022172400031879}}</ref> was the first experiment suggesting that bacteria are capable of transferring genetic information through a process known as [[Transformation (genetics)|transformation]].<ref>{{cite journal|last1=Lorenz|first1=M. G.|last2=Wackernagel|first2=W.|title=Bacterial gene transfer by natural genetic transformation in the environment|journal=[[Microbiology and Molecular Biology Reviews|Microbiological Reviews]]|volume=58 |issue=3|pages=563–602 |date=1994-09-01 |pmid=7968924|pmc=372978 |doi=10.1128/MMBR.58.3.563-602.1994}}</ref><ref>{{cite journal|last=Downie|first=A. W.|title=Pneumococcal transformation — a backward view: Fourth Griffith Memorial Lecture|journal=[[Microbiology (journal)|Journal of General Microbiology]]|url=http://mic.sgmjournals.org/content/73/1/1.full.pdf |archive-url=https://web.archive.org/web/20120302055304/http://mic.sgmjournals.org/content/73/1/1.full.pdf |archive-date=2012-03-02 |url-status=live|volume=73|issue=1|pages=1–11|year=1972|doi=10.1099/00221287-73-1-1|pmid=4143929|access-date=2011-11-30|doi-access=free}}</ref> Griffith's findings were followed by [[Avery–MacLeod–McCarty experiment|research in the late 1930s and early 40s]] that isolated [[DNA]] as the material that communicated this genetic information. | '''Griffith's experiment''',<ref>{{Cite book|url=http://dx.doi.org/10.21428/cdd5dd5a|title=Experiment|publisher=PubPub|doi=10.21428/cdd5dd5a}}</ref> performed by [[Frederick Griffith]] and reported in 1928,<ref>{{cite journal |last=Griffith|first=Fred.|author-link=Frederick Griffith|title=The Significance of Pneumococcal Types|journal=Journal of Hygiene |publisher=Cambridge University Press|date=January 1928|volume=27|issue=2|pages=113–159|jstor=4626734 |pmid=20474956 |pmc=2167760 |doi=10.1017/S0022172400031879}}</ref> was the first experiment suggesting that bacteria are capable of transferring genetic information through a process known as [[Transformation (genetics)|transformation]].<ref>{{cite journal|last1=Lorenz|first1=M. G.|last2=Wackernagel|first2=W.|title=Bacterial gene transfer by natural genetic transformation in the environment|journal=[[Microbiology and Molecular Biology Reviews|Microbiological Reviews]]|volume=58 |issue=3|pages=563–602 |date=1994-09-01 |pmid=7968924|pmc=372978 |doi=10.1128/MMBR.58.3.563-602.1994}}</ref><ref>{{cite journal|last=Downie|first=A. W.|title=Pneumococcal transformation — a backward view: Fourth Griffith Memorial Lecture|journal=[[Microbiology (journal)|Journal of General Microbiology]]|url=http://mic.sgmjournals.org/content/73/1/1.full.pdf |archive-url=https://web.archive.org/web/20120302055304/http://mic.sgmjournals.org/content/73/1/1.full.pdf |archive-date=2012-03-02 |url-status=live|volume=73|issue=1|pages=1–11|year=1972|doi=10.1099/00221287-73-1-1|pmid=4143929|access-date=2011-11-30|doi-access=free}}</ref> Griffith's findings were followed by [[Avery–MacLeod–McCarty experiment|research in the late 1930s and early 40s]] that isolated [[DNA]] as the material that communicated this genetic information. | ||
[[Pneumonia]] was a serious cause of death in the wake of the [[1918 flu pandemic|post-WWI Spanish influenza pandemic]], and Griffith was studying the possibility of creating a [[vaccine]]. Griffith used two [[Strain (biology)|strain]]s of pneumococcus (''[[Diplococcus pneumoniae]]'') bacteria which infect [[mouse|mice]] – a type III-S (smooth) which was [[virulent]], and a type II-R (rough) strain which was nonvirulent. The III-S strain synthesized a [[polysaccharide]] capsule that protected itself from the host's [[immune system]], resulting in the death of the host, while the II-R strain did not have that protective capsule and was defeated by the host's immune system. A German bacteriologist, [[Fred Neufeld]], had discovered the three pneumococcal types (Types I, II, and III) and discovered the [[quellung reaction]] to identify them ''in vitro''.<ref>{{cite book| url = https://books.google.com/books?id=iwDn7ubDO2kC| title = Lehrer, Steven. Explorers of the Body. 2nd edition 2006 p 44| isbn = 9780595407316| last1 = Lehrer| first1 = Steven| year = 2006| publisher = iUniverse}}</ref> Until Griffith's experiment, bacteriologists believed that the types were fixed and unchangeable, from one generation to another. | [[Pneumonia]] was a serious cause of death in the wake of the [[1918 flu pandemic|post-WWI Spanish influenza pandemic]], and Griffith was studying the possibility of creating a [[vaccine]]. Griffith used two [[Strain (biology)|strain]]s of pneumococcus (''[[Diplococcus pneumoniae|Streptococcus pneumoniae]]'') bacteria which infect [[mouse|mice]] – a type III-S (smooth) which was [[virulent]], and a type II-R (rough) strain which was nonvirulent. The III-S strain synthesized a [[polysaccharide]] capsule that protected itself from the host's [[immune system]], resulting in the death of the host, while the II-R strain did not have that protective capsule and was defeated by the host's immune system. A German bacteriologist, [[Fred Neufeld]], had discovered the three pneumococcal types (Types I, II, and III) and discovered the [[quellung reaction]] to identify them ''in vitro''.<ref>{{cite book| url = https://books.google.com/books?id=iwDn7ubDO2kC| title = Lehrer, Steven. Explorers of the Body. 2nd edition 2006 p 44| isbn = 9780595407316| last1 = Lehrer| first1 = Steven| year = 2006| publisher = iUniverse}}</ref> Until Griffith's experiment, bacteriologists believed that the types were fixed and unchangeable, from one generation to another. | ||
In this experiment, [[bacterium|bacteria]] from the III-S strain were killed by heat, and their remains were added to II-R strain bacteria. While neither alone harmed the mice, the combination was able to kill its host. Griffith was also able to isolate both live II-R and live III-S strains of pneumococcus from the blood of these dead mice. Griffith concluded that the type II-R had been "transformed" into the lethal III-S strain by a "transforming principle" that was somehow part of the dead III-S strain bacteria. | In this experiment, [[bacterium|bacteria]] from the III-S strain were killed by heat, and their remains were added to II-R strain bacteria. While neither alone harmed the mice, the combination was able to kill its host. Griffith was also able to isolate both live II-R and live III-S strains of pneumococcus from the blood of these dead mice. Griffith concluded that the type II-R had been "transformed" into the lethal III-S strain by a "transforming principle" that was somehow part of the dead III-S strain bacteria. | ||
Latest revision as of 18:47, 28 June 2025
Griffith's experiment,[1] performed by Frederick Griffith and reported in 1928,[2] was the first experiment suggesting that bacteria are capable of transferring genetic information through a process known as transformation.[3][4] Griffith's findings were followed by research in the late 1930s and early 40s that isolated DNA as the material that communicated this genetic information.
Pneumonia was a serious cause of death in the wake of the post-WWI Spanish influenza pandemic, and Griffith was studying the possibility of creating a vaccine. Griffith used two strains of pneumococcus (Streptococcus pneumoniae) bacteria which infect mice – a type III-S (smooth) which was virulent, and a type II-R (rough) strain which was nonvirulent. The III-S strain synthesized a polysaccharide capsule that protected itself from the host's immune system, resulting in the death of the host, while the II-R strain did not have that protective capsule and was defeated by the host's immune system. A German bacteriologist, Fred Neufeld, had discovered the three pneumococcal types (Types I, II, and III) and discovered the quellung reaction to identify them in vitro.[5] Until Griffith's experiment, bacteriologists believed that the types were fixed and unchangeable, from one generation to another.
In this experiment, bacteria from the III-S strain were killed by heat, and their remains were added to II-R strain bacteria. While neither alone harmed the mice, the combination was able to kill its host. Griffith was also able to isolate both live II-R and live III-S strains of pneumococcus from the blood of these dead mice. Griffith concluded that the type II-R had been "transformed" into the lethal III-S strain by a "transforming principle" that was somehow part of the dead III-S strain bacteria.
Scientific advances since then have revealed that the "transforming principle" Griffith observed was the DNA of the III-s strain bacteria. While the bacteria had been killed, the DNA had survived the heating process and was taken up by the II-R strain bacteria. The III-S strain DNA contains the genes that form the smooth protective polysaccharide capsule. Equipped with this gene, the former II-R strain bacteria were now protected from the host's immune system and could kill the host. The exact nature of the transforming principle (DNA) was verified in the experiments done by Avery, McLeod and McCarty and by Hershey and Chase.
Notes
References
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- (References the original experiment by Griffith. Original article and 35th anniversary reprint available.)
Further reading
- Script error: No such module "citation/CS1". 854 pages. Template:ISBN
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