dna’s discovery and structure
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DNA’s Discovery and Structure. Scientists that determined DNA’s Structure and Importance. 1866 Gregor Mendel – demonstrated that parents pass traits to offspring-thought traits contained in a molecule 1869 Friedrich Meisher – Isolated DNA from cell nucleus – named it nucleic acid - PowerPoint PPT PresentationTRANSCRIPT
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DNA’s Discovery and Structure
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Scientists that determined DNA’s Structure and Importance
1866 Gregor Mendel – demonstrated that parents pass traits to offspring-thought traits contained in a molecule
1869 Friedrich Meisher – Isolated DNA from cell nucleus – named it nucleic acid
1889 R.A. Altman-determined the chemical composition of DNA
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Scientists that Determined DNA’s Structure and Importance
1919 Phoebus Levene – Determined the structure of a DNA nucleotide
– first to propose that DNA was a polymer made of nucleotides
P = Phosphate S= 5C sugar B= Nitrogen base
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Scientists that Determined DNA’s Structure and Importance
@1928 Frederick Griffith – bacterial transformation – traits passed by a chemical
“transforming principle”@
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Scientists that Determined DNA’s Structure and Importance
1944 Oswald Avery – DNA = key to transformation - Avery and his partners conducted experiments which proved that DNA was Griffith’s “transforming principle”
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Scientists that Determined DNA’s Structure and Importance
1949 Erwin Chargaff – base-pairing rules %Adenine=%Thymine %Guanine=%Cytosine
1952 Alfred Hershey & Martha Chase– Radioactive labeled Bacteriophage
transformation experiment-settled DNA-protein debate
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Hershey & Chase
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Important Scientists in the “Race for the Double Helix”
1952Maurice Wilkins & Rosalind Franklin– X-ray diffraction- “photographs” of DNA – DNA must be a some type of spiral (helix)– DNA’s diameter is constant and stable
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Important Scientists in the “Race for the Double Helix”
1953 James Watson & Francis Crick– @Created the first accurate 3-D model of
DNA@– Won the Nobel Prize with Wilkins
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DNA’s Structure
DNA is composed of nucleotides
DNA contains four nitrogen bases: adenine(A) cytosine(C) guanine(G) thymine (T) @A & G are purines C & T are pyrimidines@
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DNA’s Structure
DNA is a double helix -2 strands of DNA nucleotides joined to form a “twisted ladder” -the strands are held by hydrogen bonds between
the nitrogen bases
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Chargaff’s Rule
The nitrogen bases form the “steps” on the DNA ladder by complementary pairing
A == TC == GT == AG == C A == T @A always pairs with TT == A C always pairs with
G@
Sugar-phosphate backbone
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How the Code Works
The combination of A,T,G,C determines what traits you might have..
C A T C A T = purple hair
T A C T A C = yellow hair
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How the Code Works
Think of the bases of DNA like letters
Letters form words…
Words form sentences..
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Central Dogma of Molecular Biology
1958 Francis Crick proposed: @DNA codes for the production of RNA RNA codes for the production of protein@ Protein does not code for the production of
protein DNA or RNA
“Once information has passed into protein it cannot get back out again”
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Who discovered the bacterial transformation?
A. Watson and CrickB. Wilkins and FranklinC. GriffithD. Avery
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Who created the first 3D model of the double helix DNA?
A. Watson and CrickB. Wilkins and FranklinC. GriffithD. Avery
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What is the complementary strand to C G T A
G C A T