DNA’s Discovery and Structure
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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 Presentation
Transcript of DNA’s Discovery and Structure
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
1889 R.A. Altman-determined the chemical composition of DNA
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
Scientists that Determined DNA’s Structure and Importance
@1928 Frederick Griffith – bacterial transformation – traits passed by a chemical
“transforming principle”@
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”
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
Hershey & Chase
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
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
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@
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
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
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
How the Code Works
Think of the bases of DNA like letters
Letters form words…
Words form sentences..
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”
Who discovered the bacterial transformation?
A. Watson and CrickB. Wilkins and FranklinC. GriffithD. Avery
Who created the first 3D model of the double helix DNA?
A. Watson and CrickB. Wilkins and FranklinC. GriffithD. Avery
What is the complementary strand to C G T A
G C A T
