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Deoxyribonucleic Acid (DNA). Students will be successful when they can…….. When they can summarize the experiments leading to the discovery of DNA as the genetic material Diagram and label the basic structure of DNA Describe the basic structure of the eukaryotic chromosome.

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Deoxyribonucleic acid dna

Deoxyribonucleic Acid(DNA)

Students will be successful when they can……..

When they can summarize the experiments leading to the discovery of DNA as the genetic material

Diagram and label the basic structure of DNA

Describe the basic structure of the eukaryotic chromosome


Discovering dna the fredrick griffith experiment 1928
Discovering DNAThe Fredrick Griffith Experiment (1928)


  • Griffith used two different strains of a bacteria that causes Pneumonia (Streptococcus pneumoniae)

  • One strain had a sugar coat (the S strain), and caused pneumonia killing a mouse by injection.

  • the other did not have a coat and is referred to as the rough strain (R strain). It did not kill the mouse by injection.


  • Griffith discovered that if he heated the S strain it would die, and no longer kill the mouse.

  • But, if he mixed the heated S strained with some live R strain (non disease-causing) the R strain would be transformed into the S strain, killing the mouse.

  • The Smooth strain was extracted from the dead mouse and cultured. It was still the rough strain, but had developed characteristics of the disease causing strain.


Griffith s conclusions
Griffith’s Conclusions die, and no longer kill the mouse.

  • Griffith concluded that there had been a transformation from the live R bacteria to Live S bacteria.

  • This experiment set the stage for the search to identify the transforming substance.


Oswald avery s experiment 1944
Oswald Avery’s Experiment (1944) die, and no longer kill the mouse.

  • Avery and Colleagues identified the molecule that transformed the R strain of bacteria into the S strain.

  • He isoladed different macromolecules, such as DNA, Protien, and lipids.

  • When the live R strain was exposed to the DNA of the S strains DNA, it was transformed into the disease causing S strain.


Hershey and chase experiment 1952
Hershey and Chase Experiment (1952) die, and no longer kill the mouse.

  • Alfred Hershey and Martha Chase published results of experiments that provided definitive evidence that DNA is the transforming factor


The experiment
The Experiment die, and no longer kill the mouse.

  • Hershey and Chase used a new technique called radioactive labeling using radio-active Phosphorus(P32) and Radioactive sulfur (S35).

  • Proteins take up sulfur not phosphorus, so the proteins are labeled.

  • DNA takes up Phosphorus, but not sulfur, therefore labeling the DNA.


Viruses and Bacteria are Grown in Medium Containing die, and no longer kill the mouse.32P, and another group of Viruses are grown in a medium of 35S. And then Blended up


The Blender dislodges the viruses from the bacteria cells, and the bacteria is seperated from the liquid containing the viruses.


Results of the hershey chase experiment
Results of the Hershey Chase Experiment and the bacteria is seperated from the liquid containing the viruses.

  • Results: bacterial cells infected with the radioactive label of 32P had incorporated 32P into its cells.

  • The bacteria infected with the 35S did not incorporate it into itself, the 35S was left in the broth.


Conclusions
Conclusions and the bacteria is seperated from the liquid containing the viruses.

DNA not Protein was the genetic material that could be passed from generation to generation in viruses.


Ii dna structure
II. DNA Structure and the bacteria is seperated from the liquid containing the viruses.

  • After Hershey and Chase found that DNA was the molecule responsible for inheritance a scientific race had begun to discover the structure of the DNA molecule.


What is a nucleotide
What is a Nucleotide and the bacteria is seperated from the liquid containing the viruses.

The structure of Nucleotides includes: A phosphate sugar backbone, with one of the 5 nitrogenous bases (ATCG,U).


The 4 nucleotide bases of dna and uracil rna
The 4 Nucleotide and the bacteria is seperated from the liquid containing the viruses.basesof DNA and Uracil (RNA)

Uracil (only found in bacterial RNA)


We ve seen this structure before this is a molecular homology and evidence for evolution
We’ve seen this structure before!! and the bacteria is seperated from the liquid containing the viruses.(this is a molecular homology, and evidence for evolution)


The brilliance of erwin chargaff 1950
The Brilliance of Erwin Chargaff (1950) and the bacteria is seperated from the liquid containing the viruses.

  • Chargraff analyzed the numbers of each nucleotide (GCTA) in the entire genomes of different species. Here’s what he found!


DUDE!!! The number and the bacteria is seperated from the liquid containing the viruses.

Of Adenine and Thymine

Are the Same!!!!

Dude!!! The number of

Cytosine and Guanine

Match Too!!!!


DUDE!!!! So, What!!! and the bacteria is seperated from the liquid containing the viruses.

Well, for starters it implies that the Adenine and Thymine are related some how, as well as Cytosine and Guanine?

Like, maybe they’re totally complementary base pairs. DUDE!!!


Rosalind franklin
Rosalind Franklin and the bacteria is seperated from the liquid containing the viruses.

  • Rosalind Franklin took a new job at King’s college in London working with a technique called X-ray Diffraction.

  • X-ray diffraction shoots X-rays at molecules and measure how the energy waves are broken up. Allowing photographs of molecules to be taken.


Photograph 51
Photograph 51 and the bacteria is seperated from the liquid containing the viruses.

  • Photograph 51 showed a pattern describing a double helix.

  • This photograph along with other data was taken without her knowledge by her Mentor and shared with two other scienctists.


James watson and francis crick
James Watson and Francis Crick and the bacteria is seperated from the liquid containing the viruses.

  • Both were working at Cambridge University (London) when they saw Rosalind photograph.

  • They soon realized that structure of the DNA was a double helix, and built their famous model.


The dna model that won them the nobel prize
The DNA Model that won them and the bacteria is seperated from the liquid containing the viruses.the Nobel Prize

  • Two outside strands consist of alternating deoxyribose and phosphates.

  • Cytosine and guanine bases pair to each other by three hydrogen bonds

  • Thymine and adenine bases pair to each other by two hydrogen bonds


Orientation of the two strands
Orientation of the Two Strands and the bacteria is seperated from the liquid containing the viruses.

The top strand of DNA is the 5’ (5 prime) strand and at the end of the top rail is the 3’ (3 prime) and said to be 5’ to 3’ orientated.

The bottom rail is the opposite, 3’ to 5’.

This is referred to as antiparallel.


The announcement
The Announcement and the bacteria is seperated from the liquid containing the viruses.

In 1953 Watson and Crick surprised the scientific community by publishing a one-page paper in the journal Nature suggesting a structure for the DNA molecule as well as a hypothesized a method of replication.


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