1. Genetic Organisation

2. In Prokaryotes  Transcrition and translation occurs in same compartment (cytoplasm)  Simultaneous; m-RNAs are short-lived (afew minutes)  No splicing  M-RNA is not polyadenylated  No IRES in eukaryotes  No introns in prokayotes (except some bacteriophages)

3. Transcription  5’-3’ direction  Any strand of DNA can be transcribed  No need for helicases, topoisomerases, primers  RNA polymerase: 4 chains 2alpha, beta, Beta’  Promoter is recognised by the factor sigma

6.  In some cases termination  rho dependent factors, which are helicases  Rho utilisation site  80-100 bp upstream of actual terminator  In E. Coli other factors: tau, nus

7. In bacteria ribosomes  70 s = 50 S and 30 S  50 S subunits: 23 S and 5 S RNA molecules  30 S subunits: 16 S RNA and 21 polypeptides  rRNA binds to m-RNA at spesific sequences: Shine-Dalgerno sequence (RBS) partly complementary to the 3’ end of 16 S RNA

9. tRNA

10. Secretion of the proteins  Many proteins exert their functions on the cell surface or in extracellular environement  they should across the cytoplasmic membrane  GSP  Sec dependent pathway  Proteins utlising GSP have a specific sequence at their N termini, which is cleaved during the transport

11.  In Gram positive bacteria GSP is sufficient but ın Gram negative bacteria Proteins reach only to the periplasmic space

12. Gram negatives have addional mechanism: Sec dependent and Sec independent Sec dependent systems  Type II secretion system: A multiprotein complex transports proteins from the periplasmic space to the outside  Type V secretion system: The proteins have an additional sequence at the C terminus, forming pores in the outer membrane (aototransporters)

13. Sec independent systems  Types I, III and IV

14. Repair systems  Proof-reading  Miss-match repair: Methyle directed missmatch repair  Excision repair:uvrA, B and C endonucleases

15.  Post-replication (recombination) repair:

16.  SOS repair:ssDNA stimulates rec A  Rec A downregulates lex A whic repress SOS genes (18 genes)  Error prone DNA repairing system

17. MUTATION and VARIATION  BActerial populations are not homgeneous  Mutations occurr randomly (Luria-Delbruck experiment – fluctuation test, 1943)

18. Point mutation

19. Insertion mutations

20. Deletion

21. Mutants  Auxotrophs: Biochemically different from the parent (prototroph)  Resistant: Antimicrobial resistance  Spontaneous mutations approx. 1 in 1 million

22. Mutagenes  UV-light (TT- dimers formations  Mutations, replication errors)

23.  Chemicals llike:Urea, nitrous acide, benzopyrene, etc...