1. Foundations in Microbiology
PowerPoint to accompany
Foundations in Microbiology
Fifth Edition
Talaro
Chapter 4
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2. Prokaryotic Profiles: the Bacteria and the Archaea
                              
Prokaryotic Profiles: the Bacteria and the Archaea
Chapter 4

3. Fig. 4.1

4. flagella 3 parts rotates 360o 1-2 or many distributed over entire cell
filament – long, thin, helical structure composed of proteins
hook- curved sheath
basal body – stack of rings firmly anchored in cell wall
rotates 360o
1-2 or many distributed over entire cell
functions in motility

5. Fig 4.2b

6. Flagellar arrangements
monotrichous – single flagellum at one end
lophotrichous – small bunches arising from one end of cell
amphitrichous – flagella at both ends of cell
peritrichous – flagella dispersed over surface of cell, slowest

8. Fig 4.5

9. Chemotaxis
Fig 4.6

10. axial filaments
periplasmic, internal flagella, enclosed between cell wall and cell membrane of spirochetes
motility

11. Fig 4.7a b

12. fimbrae fine hairlike bristles from the cell surface
function in adhesion to other cells and surfaces

13. pili rigid tubular structure made of pilin protein
found only in Gram negative cells
Functions
joins bacterial cells for DNA transfer (conjugation)
adhesion

14. Conjugation

15. glycocalyx
Coating of molecules external to the cell wall, made of sugars and/or proteins
2 types
capsule - highly organized, tightly attached
slime layer - loosely organized and attached
functions
attachment
inhibits killing by white blood cells
receptor

16. Fig 4.10

17. 2 Types of Glycocalyx

18. Biofilms

19. Peptidoglycan
unique macromolecule composed of a repeating framework of long glycan chains cross-linked by short peptide fragments
provides strong, flexible support to keep bacteria from bursting or collapsing because of changes in osmotic pressure

20. Peptidoglycan

21. 4 groups based on cell wall composition
Gram positive cells
Gram negative cells
Bacteria without cell walls
Bacteria with chemically unique cell walls

22. Gram positive Gram negative
Fig 4.16

24. Gram positive cell wall
Consists of
a thick, homogenous sheath of peptidoglycan nm thick
tightly bound acidic polysaccharides, including teichoic acid and lipoteichoic acid
cell membrane
Retain crystal violet and stain purple

25. Gram positive wall

26. Gram negative cell wall
Consists of
an outer membrane containing lipopolysaccharide (LPS)
thin shell of peptidoglycan
periplasmic space
inner membrane
Lose crystal violet and stain red from safranin counterstain

27. Gram negative cell wall

28. Cytoplasm dense gelatinous solution of sugars, amino acids, & salts
70-80% water
serves as solvent for materials used in all cell functions

29. Chromosome
single, circular, double-stranded DNA molecule that contains all the genetic information required by a cell
DNA is tightly coiled around a protein, aggregated in a dense area called the nucleoid

30. plasmids small circular, double-stranded DNA
free or integrated into the chromosome
duplicated and passed on to offspring
not essential to bacterial growth & metabolism
may encode antibiotic resistance, tolerance to toxic metals, enzymes & toxins
used in genetic engineering- readily manipulated & transferred from cell to cell

31. ribosomes made of 60% ribosomal RNA & 40% protein
consist of 2 subunits: large & small
procaryotic differ from eucaryotic ribosomes in size & number of proteins
site of protein synthesis
All cells have ribosomes.

32. ribosomes

33. Inclusions, granules intracellular storage bodies
vary in size, number & content
bacterial cell can use them when environmental sources are depleted
Examples: glycogen, poly-b-hydroxybutyrate, gas vesicles for floating, sulfur and polyphosphate granules

34. Inclusions

35. endospores sporulation -formation of endospores
Resting, dormant cells
produced by some G+ genera: Clostridium, Bacillus & Sporosarcina
Have a 2-phase life cycle – vegetative cell & an endospore
sporulation -formation of endospores
germination- return to vegetative growth
hardiest of all life forms
withstand extremes in heat, drying, freezing, radiation & chemicals not a means of reproduction

36. endospores
resistance linked to high levels of calcium & dipicolinic acid
dehydrated, metabolically inactive
thick coat
longevity verges on immortality 25, 250 million years.
pressurized steam at 120oC for minutes will destroy.

37. endospores

38. 3 shapes of bacteria cocci - spherical bacilli - rod
spiral - helical, comma, twisted rod, spirochete

40. Methods in bacterial identification
Microscopic morphology
Macroscopic morphology – colony appearance
Physiological / biochemical characteristics
Chemical analysis
Serological analysis
Genetic & molecular analysis
G + C base composition
DNA analysis using genetic probes
Nucleic acid sequencing & rRNA analysis

41. Major Taxonomic Groups of Bacteria per Bergey’s manual
Gracilicutes – gram-negative cell walls, thin-skinned
Firmicutes – gram-positive cell walls, thick skinned
Tenericutes – lack a cell wall & are soft
Mendosicutes – archaea, primitive procaryotes with unusual cell walls & nutritional habits

42. species –a collection of bacterial cells which share an overall similar pattern of traits in contrast to other bacteria whose pattern differs significantly
strain or variety – a culture derived from a single parent that differs in structure or metabolism from other cultures of that species (biovars, morphovars)
type – a subspecies that can show differences in antigenic makeup (serotype or serovar), susceptibility to bacterial viruses (phage type) and in pathogenicity (pathotype).

43. Procaryotes with unusual characteristics

44. Rickettsias very tiny, gram-negative bacteria
most are pathogens that alternate between mammals and fleas, lice or ticks
obligate intracellular pathogens
cannot survive or multiply outside of a host cell
cannot carry out metabolism on their own
Rickettsia rickettisii – Rocky Mountain spotted fever
Rickettsia prowazekii – epidemic typhus
Coxiella burnetti – Q fever

45. Chlamydias tiny obligate intracellular parasites
not transmitted by arthropods
Chlamydia trachomatis – severe eye infection and one of the most common sexually transmitted diseases
Chlamydia psittaci – ornithosis, parrot fever
Chlamydia pneumoniae – lung infections

46. Mycoplasmas naturally lack a cell wall
stabilized by sterols, resistant to lysis
extremely small
range in shape from filamentous to coccus or doughnut shaped
Mycoplasma pneumoniae – atypical pneumonia in humans

47. Free-living nonpathogenic bacteria
Photosynthetic bacteria
Cyanobacteria
Green & purple sulfur bacteria
Gliding, fruiting bacteria
Appendaged bacteria
produce an extended process of the cell wall in form of a bud, stalk or long thread

48. Archaea: the other procaryotes
constitute third Domain Archaea
seem more closely related to Domain Eukarya than to bacteria
contain unique genetic sequences in their rRNA
have unique membrane lipids & cell wall construction
live in the most extreme habitats in nature, extremophiles
adapted to heat salt acid pH, pressure & atmosphere
includes: methane producers, hyperthermophiles, extreme halophiles, and sulfur reducers