1. Basic Bacteriology

3. Bacteria Bacteria are single-celled organisms
Contain no membrane bound nucleus
Termed prokaryotes = pre nucleus
Pro = pre
karyote = nucleus
Do not contain any other organelles (such as ER or Golgi or mitochondria)
Cytoplasm is surrounded by a lipid membrane with is surrounded by a rigid cell wall
DNA bundled in a region called the nucleoid

4. The Bacterial Cell Flagella Ribosomes Capsule Cell wall Plasma
membrane
Nucleoid region (DNA)
Pili

5. The Bacterial Cell
Nucleoid DNA

6. Bacterial Nomenclature
Binomial naming system
Two word naming system
First word is genus name
Always capitalized
Escherichia
Second word is species name
Not capitalized
coli
When writing full name genus usually abbreviated
E. coli
Full name always italicized
Or underlined

7. Bacterial Morphology Morphology classification by shape
Morphology is often expressed in the binomial naming system
Ex. Bacillus subtillis, the word Bacillus means rod
Ex. Streptococcus pyogenes, Streptococcus means a chain of spheres
Ex. Helicobacter pylori, helix shaped bacterium
Many names of bacteria do not reference there shape such as E. coli, Pseudomonas aeruginosa, or Burkholdaria cepacia.

8. Bacterial Morphology

9. Examples of Morphology
Bacteria exhibit a variety of shapes
Coccus
Spherical
Bacillus
Rod or cylinder shaped

10. Examples of Morphology
Other shapes
Coccobacillus
Short round rod
Vibrio
Curved rod
Spirillum
Spiral shaped
Spirochete
Helical shape

11. Bacterial Anatomy and Structures
Cytoplasm- fluid that fills the cell where most reactions and activities of the cell take place
Cell Membrane- barrier between the internal cell fluid (cytoplasm) and the exterior environment. It is selectively permeable only allowing in selected comounds
Cell Wall- rigid structure surrounding the cell membrane that gives bacteria there shape. Stronger than the cell membrane helps hold the cell together and maintain structural integrity. The cell wall can be of varying degrees of thickness depending on the type of bacteria
Cell capsule- slime layer that protects bacteria and helps bacteria to adhere to surfaces

12. Bacterial Anatomy and Structures
Nucleoid region- location of the genetic material (DNA) in the bacterial cell. Typically bacterial DNA is one large circular DNA molecule that is packed together by supercoiling.
*Bacterial DNA should not be referred to as a chromosome because it is not packed together using chromatin and does not resemble the organization of DNA in eukaryotes. The alternate name for bacterial DNA is genophore
Plasmid- a small genetic element of circular DNA that is separate and distinct from the nucleoid DNA. The plasmid is typically thousands of times smaller than the nucleoid DNA but often very important as it may carry genes for antibiotic drug resistance

13. Bacterial Anatomy and Structures
Flagella- long structure made of protein that propels the bacteria when it spins.
Pili- structure made of protein subunits that extend out of the cell. Function for attachment to surfaces and gliding motility.
Inclusions- small structure used to store excess material typically as nutrient reserve. Stored materials include phosphates, polysaccharides, nitrogen, sulfur, proteins and biopolymers
Ribosome- a structure consisting of protein and rRNA. It translates mRNA into a sequence of amino acids (proteins)

14. Size Distribution

15. Size in the Microbial World
Tremendous range in size
Smallest virus approximately 1/1,000,000th size of largest eukaryotic cell

16. Prokaryotic Cells Comparing Prokaryotic and Eukaryotic Cells
Prokaryote comes from the Greek words for prenucleus.
Eukaryote comes from the Greek words for true nucleus.

17. Prokaryote Eukaryote One circular chromosome, not in a membrane
No histones
No organelles
Peptidoglycan cell walls
Binary fission
Paired chromosomes, in nuclear membrane
Histones
Organelles
Polysaccharide cell walls
Mitotic spindle

18. Average size: µm  µm
Basic shapes:

19. Most bacteria are monomorphic A few are pleomorphic
Unusual shapes
Star-shaped Stella
Square Haloarcula
Most bacteria are monomorphic
A few are pleomorphic
Figure 4.5

20. Arrangements Pairs: diplococci, diplobacilli Clusters: staphylococci
Chains: streptococci, streptobacilli

21. Glycocalyx Outside cell wall Usually sticky
A capsule is neatly organized
A slime layer is unorganized & loose
Extracellular polysaccharide allows cell to attach
Capsules prevent phagocytosis
Figure 4.6a, b

22. Flagella Outside cell wall Made of chains of flagellin
Attached to a protein hook
Anchored to the wall and membrane by the basal body
Figure 4.8

23. Flagella Arrangement
Figure 4.7

24. Figure 4.8

25. Motile Cells Rotate flagella to run or tumble
Move toward or away from stimuli (taxis)
Flagella proteins are H antigens (e.g., E. coli O157:H7)

26. Motile Cells
Figure 4.9

27. Axial Filaments Endoflagella In spirochetes
Anchored at one end of a cell
Rotation causes cell to move
Figure 4.10a

28. Fimbriae allow attachment
Pili are used to transfer DNA from one cell to another
Figure 4.11

29. Cell Wall Prevents osmotic lysis Made of peptidoglycan (in bacteria)
Figure 4.6a, b

30. Peptidoglycan
Polymer of disaccharide N-acetylglucosamine (NAG) & N-acetylmuramic acid (NAM)
Linked by polypeptides
Figure 4.13a

31. Figure 4.13b, c

32. Gram-positive cell walls Gram-negative cell walls
Thick peptidoglycan
Teichoic acids
In acid-fast cells, contains mycolic acid
Thin peptidoglycan
No teichoic acids
Outer membrane

33. Gram-Positive cell walls
Teichoic acids:
Lipoteichoic acid links to plasma membrane
Wall teichoic acid links to peptidoglycan
May regulate movement of cations
Polysaccharides provide antigenic variation
Figure 4.13b

34. Gram-Negative Outer Membrane
Lipopolysaccharides, lipoproteins, phospholipids.
Forms the periplasm between the outer membrane and the plasma membrane.
Protection from phagocytes, complement, antibiotics.
O polysaccharide antigen, e.g., E. coli O157:H7.
Lipid A is an endotoxin.
Porins (proteins) form channels through membrane

35. Gram-Negative Outer Membrane
Figure 4.13c

36. Gram Stain Mechanism Crystal violet-iodine crystals form in cell
Gram-positive
Alcohol dehydrates peptidoglycan
CV-I crystals do not leave
Gram-negative
Alcohol dissolves outer membrane and leaves holes in peptidoglycan
CV-I washes out

37. Atypical Cell Walls Mycoplasmas Archaea Lack cell walls
Sterols in plasma membrane
Archaea
Wall-less, or
Walls of pseudomurein (lack NAM and D amino acids)

38. Damage to Cell Walls Lysozyme digests disaccharide in peptidoglycan.
Penicillin inhibits peptide bridges in peptidoglycan.
Protoplast is a wall-less cell.
Spheroplast is a wall-less Gram-positive cell.
L forms are wall-less cells that swell into irregular shapes.
Protoplasts and spheroplasts are susceptible to osmotic lysis.

39. Plasma Membrane
Figure 4.14a

40. Plasma Membrane Phospholipid bilayer Peripheral proteins
Integral proteins
Transmembrane proteins
Figure 4.14b

41. Fluid Mosaic Model Membrane is as viscous as olive oil.
Proteins move to function
Phospholipids rotate and move laterally
Figure 4.14b