1. How was the molecule found?
DNA Discovery
How was the molecule found?

2. Transformation
Frederick Griffith found that live strains of bacterium transformed from dead strains of pathogenic bacterium. The genetic information of dead pathogenic bacteria transformed onto live non threatening bacteria

3. Avery experiment
From no evidence was found to explain Griffiths experiment.
In 1944 Oswald Avery started to breakdown the bacterium used in the Griffith experiment.
First he removed all proteins from the bacteria but found no change in the results.
When the deoxyribose digesting enzyme was added to the bacteria, transformation could not be competed.
This proved that DNA was the acting agent to the specific trait.

4. Hershey/Chase Experiment
Hershey and Chase just after WWII used radioactive isotopes that were now available to them to track proteins and DNA in the transformation experiment. Radioactive isotope 35S was not present while radioactive 35P was and radioactive 35P was attached to DNA

5. DNA vs Protein
Griffith found that specific traits can transform the characteristics of other cells.
Avery test those results and found that when protein was removed the outcome was unchanged, but when the sugar was removed the effects were negated.
Hershey and Chase injected radioactive isotopes into each aspect of the protein and DNA and found that DNA was the molecule that moved from one cell to another, thus DNA became the molecule that controlled genetic traits within organisms.

6. The story of Watson and Crick
Rosalind Franklin carried out an X-ray diffraction experiment that bombarded the molecule of DNA and it showed it as a coiled spring.
She gave this information to Watson and Crick and they made a tinker toy of the structure known as a double helix.
Watson and Crick won the Noble peace prize, Franklin got nothing.

7. Chargaff’s base pairing rule
Chargaff measured various living organisms and found that in every organism he observed, the amount of Cytosine=Guanine and the amount of Thymine=Adenine.
The four nitrogen bases were placed into 2 groups based upon their structure.
Purines- Adenine and Guanine
Pyrimidines - Cytosine and Thymine

8. 3 Types of replication

9. Replication types
Conservative- The original strand serves as the template to create the new strands but the original reassembles as the new strand assembles with itself.
Semi-Conservative- The original strand serves as a template but the new strand joins with the original strand to make the new molecule.
Dispersive- the original strand is still the template but the new and the old strands disperse between the two new molecules

10. Antiparallel
As DNA is replicated the two new strand move in opposite directions.
As the original strand opens, the new strand travels from the opposite side of the molecule and moves up the replication fork.

11. Meselson-Stahl Experiment
This experiment showed that semiconservative replication was the typical type of replication process by injecting heavy N14 isotopes and lighter N14 isotopes into bacteria DNA and watching as they settled in a test tube after centrifugation.

12. Replication Terms
Leading Strands- part of the newly replicated DNA strand that is being created toward the replication fork.
Lagging Strand- small fragments of newly replicated DNA that are being created away from the replication fork.
Okazaki Fragment- the small fragments of lagging strands are called.
Ligase- enzyme used to connect small fragments after replication to construct the new molecules.
Primase- enzyme that creates a small segment of RNA (primer)
Single strand binding protein (SSBP)- after helicase separates strands, this enzyme keeps DNA separated and unwound.

13. Leading/Lagging strands

14. Mutations
Although DNA repair is done in every cell and proofreading is done in every daughter cell, mutations do occur.
Without mutations evolution would halt and species may not have the capabilities to continue.
With that said, let’s talk mutations!!

15. What is a Mutation
A change in the content of the genetic message (the base sequence of one or more genes).
Some alter the identity of a particular nucleotide, while others remove or add nucleotides to a gene.
Recombination- is the process of when a genetic message has a change in its’ original position. Nitrogen bases are rearranged and the code is changed.

16. Types of Mutations
Germ-Line Tissue Mutations- these mutations occur in the germ-line cells of a gamete and are now part of a hereditary endowment that will continue for future generations. These mutations have an enormous biological importance because they serve as raw material for the process of natural selection.
Somatic Tissue Mutations- Somatic cells are not passed on to future generations and can only be passed to subsequent cells that derive from the mutated cell. Lung cell passes mutation to daughter lung cells.

17. Types of Mutations Continued
Point Mutations- mutation only occurs in one or a few base pairs.
Base substitution-base is changed to a new one
Insertion- base pair is inserted into a gene
Deletion- base pair is deleted from a gene
Frame Shift mutation- insertion or deletion causes the gene message out of register. (commonly caused by mutagens)

18. Mutations
Mutagens- environmental conditions that cause the frame shift mutation. Radiation or chemicals are the major cause!!!!!!
These frame shifts cause a new amino acid to be placed within a protein that was not originally there or an amino acid is deleted from the formation of the protein.
Either way the protein is now altered and this could have catastrophic results to the organism.

19. Transposition vs. Translocation
Transposition- individual genes may move position within the structure of DNA
Translocation- when segments of a homologous pair do not exchange equally during crossing over or through random exchange. Results in serious genetic disorders like down syndrome.