1. Chapter 4 Part B Bacterial ultrastructure (continued)

2. 3) Fimbriae or pili Composed of tubular protein = pilin Contributes to pathogenicity in some bacteria 2 types of pili: both coded by genes on plasmids –Common pili/fimbriae – used for adhesion to surfaces –Conjugation/sex pilus – coded by F plasmid; aid in transfer of plasmid and chromosomal DNA

3. Common fimbriae or pili

4. 4) Glycocalyx = general term for the substances that surround bacterial cells 2 types distinguished by degree of adhesion to cell surface: Capsule – firmly attached Slime sheath – loosely attached Functions: –Aid in cell attachment –Protect vs. phagocytosis –Protect vs. dessication –Block toxins, bacteriophage, etc.

5. Glycocalyx example

6. 5) Periplasmic space Space between plasma membrane and cell wall Composed of gel- like substance = periplasm –Contains enzymes –Variety of receptors –linked to primitive sensory system… Is this cell Gram + or Gram - ?

7. 6) Plasma membrane Composed of a sel. permeable phospho- lipid bilayer Associated with intrinsic/integral proteins and extrinsic/ peripheral proteins Adheres to fluid- mosaic model

8. Plasma membrane

9. Plasma membrane regulates movement of materials across it Simple diffusion: Occurs with O2, CO2, and some small, non-polar organic molecules

10. Plasma membrane regulates movement of materials across it Facilitated diffusion: Movement of H 2 O occurs this way!!!

11. osmosis

12. Plasma membrane regulates movement of materials across it Active transport:

13. The plasma membrane in prokaryotes is MULTI-FUNCTIONAL

14. 7) Cytoplasm and the cell’s interior structures Cytoplasm is composed mostly of water It contains: –Single chromosome –Free and attached 70S ribosomes –Plasmid(s) –Inclusions Inorganic Organic

15. 8) Bacterial chromosome and nuclear area Nuclear area = “nucleoid” Haploid, just 1 chromosome; circular in many bacteria

16. 9) extra-chromosomal DNA  plasmids Circular DNA segments Replicate indep of chromosome Not req’d for host growth or reproduction Some carry genes that provide selective advantage: –R factor plasmids –Virulence factor plasmids

17. 10) Bacterial ribosomes (70S) Site of protein synthesis Composed of 2 subunits, each containing protein and rRNA –Small subunit (30S) –Large subunit (50S) Certain antibiotics (streptomycin, neomycin, tetracycline) affect 70S ribosome, not 80S ribosomes

18. 11) Inclusion bodies Organic inclusions Inorganic inclusions

19. 12) Endospores