Molecular Basis of Inheritance: From Griffith's Transformation Principle to Avery's DNA Identification
1
SNS
ACADEMY
A fingerprint International School
Affiliated to CBSE New Delhi
Affiliation No :1930610
GRADE XII A (2020-21)
COURSE NAME
: BIOLOGY
(044)
Chapter-6 MOLECULAR BASIS OF INHERITANCE- THE
SEARCH FOR GENETIC MATERIALS
Transforming Principle
•
Frederick Griffith - 1928
•
Streptococcus pneumonia
•
On culture media - some are smooth or shiny colonies (S)
-rough colonies (R)
-
Due to the presence and absence of mucous (polysaccharide)
-
crystal violet-nalidixic acid-gentamicin agar:CVNG)
2
Frederick Griffith
o
Streptococcus pneumoniae
model
o
S encapsulated and virulent; R
non-encapsulated and non-
virulent
o
Heat killed S cells mixed with
R cells created S cells
o
Concluded that S cells have a
chemical component that can
transform other cells
3
4
Biochemical characteristics of
transforming principle
•
Oswald avery, Colin
MacLeod and Maclyn
McCarty
5
6
Oswald Avery
•
Identified the transforming substance from Griffith’s work as
DNA
–
Focused on DNA, RNA, and protein
•
Extract components from pathogenic bacteria
–
Each individually inactivated and tested for transformation ability
•
Degradation of DNA only substance to prevent
•
Not uniformly supported
–
Proteins better candidates
–
Doubted bacterial DNA similar to that of complex organisms
–
Little still known about DNA
7
Hershey and chase experiment
•
The proof – DNA is the genetic material – Alfred
Hershey and Martha Chase.
8
9
Discover the fascinating journey of uncovering genetic materials, from Frederick Griffith's transformation principle with Streptococcus pneumoniae to Oswald Avery's identification of DNA as the transforming substance. Follow the biochemical characteristics studied by Avery, MacLeod, and McCarty, leading to the Hershey and Chase experiment validating DNA as the genetic material. Delve into the advancements that shaped our understanding of heredity and genetic information.
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SNS ACADEMY A fingerprint International School Affiliated to CBSE New Delhi Affiliation No :1930610 GRADE XII A (2020-21) COURSE NAME : BIOLOGY(044) Chapter-6 MOLECULAR BASIS OF INHERITANCE- THE SEARCH FOR GENETIC MATERIALS 1
Transforming Principle Frederick Griffith - 1928 Streptococcus pneumonia On culture media - some are smooth or shiny colonies (S) -rough colonies (R) -Due to the presence and absence of mucous (polysaccharide) -crystal violet-nalidixic acid-gentamicin agar:CVNG) 2
Frederick Griffith o Streptococcus pneumoniae model o S encapsulated and virulent; R non-encapsulated and non- virulent o Heat killed S cells mixed with R cells created S cells o Concluded that S cells have a chemical component that can transform other cells 3
Biochemical characteristics of transforming principle Oswald avery, Colin MacLeod and Maclyn McCarty 5
Oswald Avery Identified the transforming substance from Griffith s work as DNA Focused on DNA, RNA, and protein Extract components from pathogenic bacteria Each individually inactivated and tested for transformation ability Degradation of DNA only substance to prevent Not uniformly supported Proteins better candidates Doubted bacterial DNA similar to that of complex organisms Little still known about DNA 7
Hershey and chase experiment The proof DNA is the genetic material Alfred Hershey and Martha Chase. 8
