1. Selected topics in molecular biology Review session Nov. 26, 2007

2. All nucleotides have a common structure

3. There are five principal bases in nucleic acids A, G, T, C are present in DNA A, G, U, C are present in RNA Inosine is carbonylated adenosine

4. UMP

5. 1) Ribonucleotide reductase catalyzes the synthesis of deoxyribonucleotides Inhibited by hydroxyurea, which is used as anti-cancer drug 2) Thymidylate synthase catalyzes the methylation of dUTP Conversion of ribo-to-deoxyribonucleotides UMP

6. Anti-cancer drugs specifically block dTMP production Folic acid

7. Defects in the purine salvage pathway cause human diseases Salvage Pathway Activated ribose (PRPP) + base Nucleotides De Novo Pathway Activated ribose (PRPP) + amino acids + ATP + CO 2 +………. Nucleotides Blocked by HGPRT deficiency (Gout, Lesh-Nyhan) PRPP

8. DNA can undergo reversible strand separation

15. The eukaryotic replication fork Replication protein A Replication factor C

16. Inhibited by rifamycins (e.g., Rifampicin)

17. The base pair in the 3 rd codon position can “wobble”

18. frameshift mutations

19. Exchange of genetic material during meiosis Recombination=crossover + exchange of DNA between two DNA double strands

20. Organization and rearrangement of heavy-chain DNA V=variable D=diversity J=joining C=constant VDJ recombination allows for antibody diversity

21. Different classes of immunoglobulin (isotypes) fulfill different tasks major class major class membrane- unknown against In serum in external bound parasites, secretions allergies 1 st line of defense

22. Cell Cycle Control

23. Multiple cdks and cyclins regulate passage of mammalian cells through the cell cycle Restriction point is analogous to START Cdc2/Cdk1-cyclin B Cdc2/Cdk1-cyclin A Cdk2-cyclin A Cdk2-cyclin E Cdk4-cyclin D Cdk6-cyclin D

25. good genes bad genes proto-oncogenes oncogenes are required for promote uncontolled normal growth growth gain-of-function mutation (can be point mutation, insertion or deletion) Besides mutations in proto-oncogene/tumor suppressor coding regions, mutations in gene regulatory elements (promoter) can deregulate the expression pattern tumor suppressors inactive tumor suppressor loss-of-function mutation

26. Membrane receptors and signal transduction cascades

27. Cell-surface receptors belong to different classes

28. G protein-coupled receptors contain 7 transmembrane alpha-helices

29. Acetylcholine receptor in the heart muscle opens K + channels frequency of heart contractions goes down