1. Agenda -DNA as hereditary material - DNA Structure - -DNA Replication - - Telomers - - Mutation - - Gene Function (Beadle and Tatum) - Transcription - mRNA modifications Genetics Test Review (Ch. 14, 15, 16)

2. DNA as Hereditary Material Griffith: found out that R-strain bacteria can be transformed into S-strain by some sort of genetic material Avery: Found that DNA is the transforming factor in the Griffith experiment Hersey & Chase: found that the genetic material that is injected into host cells is DNA and the phage ghost outside of the cell is protein

3. DNA Structure Chargaff: A/T= 1, G/C=1 Franklin and Wilkins: 10 basepairs or 20 single bases in one turn of the helix Phosphodiester Linkage: bond that links two nucleotides together 5’ end, 3’ end DNA is antiparallel Number of Hydrogen bonds between A-T and C-G?

4. DNA Replication Messelson and Stahl: semi-conservative replication How would you describe semi-conservative replication? What is the spot where DNA unwinding occurs called? What is this spot characterized by? 1 replicon or replication bubble has 2 replication forks What direction are nucleotides synthesized? What is the energy source for nucleotide synthesis? What is required for DNA polymerases to start synthesizing DNA?

5. DNA Replication cont. What are dNTP’s? In terms of origin of replication, how do prokaryotes and eukaryotes differ? What are Okazaki Fragments? Define the following proteins: Primase Helicase Single Stranded DNA-binding proteins Ligase What would happen if these proteins were nonfunctioning?

6. Replication DNA Pol I DNA Pol II DNA Pol III What type of cell could you find these enzymes? Which polymerase has 5’  3’ exonuclease activity?

7. Telomeres Telomeres are the ends of chromosomes that don’t code for anything In most cells, telomeres are shortened. When the telomere is shortened to a certain extent, the cell dies. What is telomerase? Where is it present?

8. Mutation Change in base pair sequence of DNA due to either mistakes in DNA replication or environmental factors In what case can a person pass on a mutation to their offspring? Mutations can be fixed by: Proofreading Mismatch Repair Nucleotide excision repair

9. Gene Function Garrod: studied AKU which is an inborn error in metabolism which is a genetic disease caused by absence of an enzyme necessary for metabolism Beadle & Tatum: one gene, one enzyme, Neurospora crassa What do prototrophic and auxotrophic mean?

10. Gene Function The medium that allows for the most growth is at the end of the pathway. The mutation that allows for the most growth is at the beginning of the pathway. ABCDE Mut 1NNNYN Mut 2NYNYY Mut 3YYNYY Mut 4NYNYN

11. Gene expression What is transcription? What is translation?

12. Transcription What enzyme transcribes? RNA Pol I RNA Pol II RNA Pol III Draw a picture of a gene. Mark transcription start and stop and translation start and stop. Also include the promoter.  These enzymes are for eukaryotic cells as opposed to the DNA Pol I, II &III for prokaryotic cells

13. Promoter Contains consensus sequences Located right before the 5’ UTR ProkaryotesEukaryotes Consensus Sequences-35 TTGACA, -10 TATAAT-25 TATAAAA, -75 CAAT, -90 GGCGGG Assistant proteins to RNA polymerase (recognizes consensus sequences) Sigma factorTranscription factors

14. Transcription Termination The following information applies to Prokaryotes: Rho-independent termination (hair pin) Rho-dependent termination (rho binds to 3’ UTR) What would happen if there weren’t any Rho protein in a bacteria cell?

15. mRNA modifications ProkaryotesEukaryotes Translation and transcription can happen at the same time because there is no nucleus. Transcription happens in the nucleus. Translation happens in the cytoplasm. Before mRNA leaves the nucleus, there must be some modifications in order to protect the fragile single stranded RNA from degradation. 1.5’ cap 2.Polyadenylation 3.Splicing