1. DNA Discovery, Structure, Replication, Transcription and Translation

2. DNA Discovery A. Meischer – 1870’s – first isolated DNA A. Meischer – 1870’s – first isolated DNA B.Griffith – 1928 studied Streptococcus pneumonia – bacteria that cause pneumonia. Used encapsulated (harmful) Streptococcus pneumonia and non- encapsulated Streptococcus pneumonia. B.Griffith – 1928 studied Streptococcus pneumonia – bacteria that cause pneumonia. Used encapsulated (harmful) Streptococcus pneumonia and non- encapsulated Streptococcus pneumonia. Injected it into ____________ (what animal) Injected it into ____________ (what animal)

3. Mouse What was injected Result Mouse 1 Mouse 2 Mouse 3 Mouse 4

4. Because the heat-killed bacteria was still able to kill the mice Griffith concluded that something n the bacterial cell was able to “Transform” and called it the Transforming Principle. Because the heat-killed bacteria was still able to kill the mice Griffith concluded that something n the bacterial cell was able to “Transform” and called it the Transforming Principle.

5. Avery, McLeod, McCarty – 1944 – proved DNA not Protein was the genetic material. Avery, McLeod, McCarty – 1944 – proved DNA not Protein was the genetic material. Hershey & Chase – 1952 - used bacteriophages (bacteria eater) to determine what the genetic material was. Hershey & Chase – 1952 - used bacteriophages (bacteria eater) to determine what the genetic material was. -They used Radioactive Tracers and tagged the protein coat of the bacteriophage with Sulfur and tagged the DNA with radioactive Phosphorus -They used Radioactive Tracers and tagged the protein coat of the bacteriophage with Sulfur and tagged the DNA with radioactive Phosphorus

6. Levene – 1920- said there were 4 nitrogen bases (Adenine, Guanine, cytosine and Thymine) and they attached to the sugars on the DNA. (TRUE). What he said that was wrong was that the DNA bases all occurred in equal numbers. (WRONG) Levene – 1920- said there were 4 nitrogen bases (Adenine, Guanine, cytosine and Thymine) and they attached to the sugars on the DNA. (TRUE). What he said that was wrong was that the DNA bases all occurred in equal numbers. (WRONG)

7. Chargaff – 1947 – said that the number of adenines equaled the number of thymine and that the number of cytosine = the number of guanines. Chargaff – 1947 – said that the number of adenines equaled the number of thymine and that the number of cytosine = the number of guanines. A=T and C=G A=T and C=G

8. Watson and Crick - 1950’s - used the information provided by the previous scientists to build a DNA model. Their most important find was that the tow sides of the DNA had to run in OPPOSITE directions! This is called antiparallel! Watson and Crick - 1950’s - used the information provided by the previous scientists to build a DNA model. Their most important find was that the tow sides of the DNA had to run in OPPOSITE directions! This is called antiparallel!

9. Kerry Mullins – 1990’s - Dreher High School Graduate developed a process called the Polymerase Chain Reaction (PCR) that allows us to make DNA replicate itself in a test tube. This allows forensic scientists to increase the amount of DNA found at a crime scene to use it for testing. Kerry Mullins – 1990’s - Dreher High School Graduate developed a process called the Polymerase Chain Reaction (PCR) that allows us to make DNA replicate itself in a test tube. This allows forensic scientists to increase the amount of DNA found at a crime scene to use it for testing.

11. II.The Structure of DNA Each DNA molecule is arranged in a double helix – two strands twisted around each other. (twisted ladder) Each DNA molecule is arranged in a double helix – two strands twisted around each other. (twisted ladder)

12. DNA molecules are composed of repeating DNA molecules are composed of repeating nucleotide subunits. Each nucleotide is composed of three parts. nucleotide subunits. Each nucleotide is composed of three parts.  a phosphate group  a five-carbon sugar (deoxyribose)  a nitrogenous base (A T C G)

13. Nitrogenous bases are divided into two categories  Purines – adenine and guanine  Pyrimidines – thymine and cytosine in DNA, bases always pair: in DNA, bases always pair:  adenine to thymine  cytosine to guanine

14. Base pairs held together by Hydrogen bonds Collectively, nucleotides bond together to form long chains. Two long chains of nucleotides pair up by matching complementary base pairs. (complete ladder) Rungs of the ladder are bound together by hydrogen bonds between the base pairs. Collectively, nucleotides bond together to form long chains. Two long chains of nucleotides pair up by matching complementary base pairs. (complete ladder) Rungs of the ladder are bound together by hydrogen bonds between the base pairs.

16. Replication DNA REPLICATION – Referred to as Semiconservative b/c one half of the DNA is the old template and the other is new DNA DNA REPLICATION – Referred to as Semiconservative b/c one half of the DNA is the old template and the other is new DNA

17. Replication Cont….. –Helicase is the enzyme that unwinds and unzips the DNA. –RNA Primase is the enzyme that adds a short segment of RNA called and RNA Primer to the strand which sends the signal to begin replication.

18. –DNA Polymerase is the enzyme that adds new DNA nucleotides to the strand along BOTH sides of the DNA –The left side is the Leading Daughter Strand and is replicated in one section.

19. –The right side is the Lagging Daughter Strand and is replicated in small pieces (Okazaki fragments) that are later bound together by the enzyme Ligase into one long strand. –DNA Polymerase also removes the RNA Primers before the Lagging Strands are bound together.

20. Lets See It Lets See It http://www.johnkyrk.com/DNAreplication. html http://www.johnkyrk.com/DNAreplication. html http://www.johnkyrk.com/DNAreplication. html http://www.johnkyrk.com/DNAreplication. html