DNA The Code of Life 6 1 Frederick

Friedrich Miescher (1869) isolated a substance he called “nuclein” (DNA) from the nuclei of

Joachim Hammerling (1930 s) experiments with Acetabularia, a single-celled algae 1934: determined the nucleus

1943: When nuclei were swapped between two different organisms, the resultant growth showed traits

Alfred Hershey & Martha Chase (1952) experiments with bacteriophage T 2 determined hereditary material

Phoebus Levene (1920’s) identified the 3 components of DNA: deoxyribose sugars phosphate groups nitrogenous

Erwin Chargaff (1940) isolated DNA from different organisms and measured levels of the nitrogenous

Chargaff’s Law If 24% of a DNA sample is adenine, what % is a)

$Rosalind Franklin produced X-ray diffraction images of DNA suggested the double helix shape$

James Watson & Francis Crick (1953) proposed model of DNA with a double helix

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DNA & The Code of Life 6. 1

Frederick Miescher

Friedrich Miescher (1869) isolated a substance he called “nuclein” (DNA) from the nuclei of cells Heredity was thought at this time to be passed on through proteins

Joachim Hammerling (1930 s) experiments with Acetabularia, a single-celled algae 1934: determined the nucleus contained genetic material

1943: When nuclei were swapped between two different organisms, the resultant growth showed traits of the plant that the nucleus was from, rather than the host plant.

Alfred Hershey & Martha Chase (1952) experiments with bacteriophage T 2 determined hereditary material is DNA, not protein

Hershey – Chase Experiment

Phoebus Levene (1920’s) identified the 3 components of DNA: deoxyribose sugars phosphate groups nitrogenous bases Thymine Adenine Guanine cytosine

Erwin Chargaff (1940) isolated DNA from different organisms and measured levels of the nitrogenous bases He found that… amt. of adenine = amt. of thymine amt. of cytosine = amt. of guanine Became known as Chargaff’s law

Chargaff’s Law If 24% of a DNA sample is adenine, what % is a) thymine, b) cytosine, c) guanine? % thymine = % adenine = 24% % cytosine + % guanine = (100 -24 -24) = 52% %cytosine = % guanine = 52/2 = 26%

$Rosalind Franklin produced X-ray diffraction images of DNA suggested the double helix shape$

Rosalind Franklin produced X-ray diffraction images of DNA suggested the double helix shape

James Watson & Francis Crick (1953) proposed model of DNA with a double helix of 2 anti-parallel strands won the Nobel Prize in 1962 (with Maurice Wilkins)