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THEFIVE
KINGDOMS
INFERTILE
HYBRIDS
A mule
A Tigron
Differences within a species
HEREDITHEREDITYY
Transmissio
n of characteristi
cs from parents to offspring
It must be able to control expression of traits
It must be able to replicate in order to be in each
cell of the organism
It must be able to change in order to ensure survival of a species in a changing
environment
CHARACTERISTICS OF HEREDITARY MATERIAL
Fred Griffith (1928) – proposed a “transforming principle” as being responsible for changing a non-pathogenic strain of bacteria into a pathogenic strain.Click here to see image
Oswald Avery (1944) – showed Griffith’s “transforming principle” to be DNA.
Alfred Hershey & Martha Chase (1952) – confirmed Avery’s result using T2 bacteriophage. Click here to see image
THE SEARCH FOR THE AGENT OF
HEREDITY
GENE
Unit of inheritance
Discrete section of DNA
Carries information for specific proteins
GENE EXPRESSIONGENE EXPRESSION The process of
transferring information encoded in a gene into its functional product
• Erwin Chargaff (1950) – A and T in equal amounts, likewise G and C, in all organisms.
• Rosalind Franklin & Maurice Wilkins (1951) – produced an X-ray diffraction picture of DNA suggesting a helical structure.
• James Watson & Francis Crick (1953) – definitive 3-D structure of DNA.
• Matthew Meselson & Franklin Stahl (1958) – showed DNA replication to be semi-conservative.
• Marshall Nirenberg & Gobind Kharana (1966) – cracked the genetic code.
A STRUCTURE FOR DNA
End of Slide Show Click Here
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Back to heredity search
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