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Functional Anatomy of Prokaryotic and Eukaryotic Cells

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Chapter 3 Functional Anatomy of Prokaryotic and Eukaryotic Cells Photosynthetic pigments on in-foldings chromatophores or thylakoids Archaea have distinct membrane ... – PowerPoint PPT presentation

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Title: Functional Anatomy of Prokaryotic and Eukaryotic Cells


1
Chapter 3
  • Functional Anatomy of Prokaryotic and Eukaryotic
    Cells

2
  • Prokaryotes can be grouped based on size,
    morphology and cell arrangement
  • Morphology is genetically determined
  • Monomorphic vs pleomorphic
  • Size Range
  • 0.2 to 80 um in diameter
  • 2 to 600 um in length
  • Average size 0.2 -1.0 µm 2 - 8 µm

3
Size in the Microbial World
4
Morphology of Prokaryotic Cells
  • Prokaryotes exhibit a variety of shapes
  • Most common

5
  • Spiral

6
  • Uncommon Shapes

Stella
Haloarcula
7
  • Cells may form groupings
  • Cells adhere together after division
  • Form characteristic arrangements
  • Depends on plan of division

8
Neisseria Enterococcus
Micrococcus Sarcina
Staphylococcus aureus
9
Bacillus anthracis Bacillus megaterium
Bordetella pertussis
10
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11
Layers External to Cell Wall
  • Glycocalyx
  • Made inside the cell excreted to surface
  • General functions
  • Protection
  • Attachment
  • Motility

12
  • Arrangements of Glycocalyx
  • Capsule or Slime Layer
  • Chemical composition varies depending on species

13
Flagella
  • Filamentous appendages composed of flagellin
  • H antigens
  • Rotate powered by PMF or ATP
  • Taxis
  • Runs and tumbles

14
  • Flagella structure has three basic parts
  • Filament
  • Hook
  • Basal body

15
Polar - Monotrichous
Polar -Lophotrichous
Peritrichous
Polar -amphitrichous
16
Axial filaments
  • Bundles of endoflagella that spiral around cell
  • Spirochetes only
  • Corkscrew motion

17
Fimbriae Pili
  • Filaments of pilin protein
  • Fimbriae
  • Attachment
  • Hami archaea only
  • Pili
  • Exchange of DNA

18
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19
Prokaryotic Cell Wall
  • Rigid structure
  • Determines shape of cell
  • Protects from osmotic pressure
  • Anchor point for flagella
  • Contributes to pathogeneses

20
  • Unique chemical structure
  • Bacteria vs. Archaea
  • Gram positive vs. Gram-negative
  • Peptidoglycan (PTG) (murein)
  • Sugar found only in bacteria
  • Archaea may have proteins or alternate sugars
  • Many antimicrobials interfere with PTG synthesis
  • Penicillin

21
  • Basic structure of PTG
  • Disaccharide polymer
  • N-acetylglucosamin (NAG)
  • N-acetylmuramic acid (NAM)
  • Glycan chain held together by amino acids
  • Tetrapeptide chain
  • Protein crossbridges may or may not be present
  • Mostly G

22
  • Gram positive cell wall
  • Thick layer of PTG
  • Teichoic acids
  • Lipoteichoic or Wall teichoic acids
  • Polyalcohols that provide antigenic specificity
  • May have external protein or sugar layer

23
  • Gram-negative cell wall
  • Little or no PTG
  • Outer lipopolysaccharide membrane (LPS)
  • O-specific polysaccharide side chain
  • Lipid A endotoxin
  • Porin channels
  • Periplasm

24
GRAM STAINING
  • Gram-positive and gram-negative bacteria can be
    identified using a gram stain

25
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26
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27
Summary of Gram vs. Gram
  • G cell
  • many rigid layers of peptidoglycan
  • teichoic acids
  • No outer LPS membrane
  • 2 ring basal body anchoring flagella
  • G- cell
  • Little or no peptidoglycan
  • no teichoic acids
  • LPS outer membrane
  • 4 ring basal body anchoring flagella

28
Atypical cell wall
  • Acid-fast cell walls
  • Classified as gram-positive
  • mycolic acid bound to PTG
  • Mycobacterium
  • Nocardia

29
  • Chlamydia
  • Classified as Gram with no PTG
  • cysteine-rich proteins

30
  • No cell wall
  • Mycoplasmas
  • Sterols in plasma membrane

31
Structures Internal to Cell Wall
  • Cytoplasmic membrane
  • Delicate thin fluid structure
  • Defines boundary
  • Serves as a semi permeable barrier

32
  • Fluid mosaic model
  • Phospholipid Bilayer
  • Amphipathic

33
  • Embedded with numerous proteins
  • receptors , transport, enzymes
  • Prokaryotes do not have membrane sterols
  • Bacteria may have hopanoids

34
  • Photosynthetic pigments on in-foldings
  • chromatophores or thylakoids

35
  • Archaea have distinct membrane lipids
  • Ether linkage
  • Diether or tetraether
  • Glycerol group enantiomer
  • Branched isoprenoid sidechain
  • May form mono-layer with greater rigidity

36
Top archaeal phospholipid, 1 isoprene sidechain,
2 ether linkage, 3 L-glycerol, 4 phosphate
group Middlebacterial and eukaryotic
phospholipid 5 fatty acid, 6 ester linkage, 7
D-glycerol, 8 phosphate group Bottom 9 lipid
bilayer of bacteria and eukaryotes, 10 lipid
monolayer of some archaea.
37
  • Membrane is selectively permeable
  • Few molecules pass through freely
  • Movement involves both active and passive
    processes

38
  • passive processes
  • no energy (ATP) required
  • Along gradient
  • simple diffusion, facilitated diffusion, osmosis

39
  • Simple diffusion
  • Facilitated diffusion

40
  • Osmosis
  • Osmotic pressure

41
  • active processes
  • energy (ATP) required
  • Active transport

42
  • Group translocation
  • Phosphotransferase system
  • PEP group translocation

PEP transferase animation
43
Internal Structures
  • Structures essential for life
  • Chromosome
  • Ribosome
  • Optional but may provide selective advantage
  • Cytoskeleton
  • Plasmid
  • Storage granules
  • Endospores

44
Internal Structures
  • Primary Chromosome
  • Resides in nucleoid
  • Typically single circular chromosome
  • Archaea have histone proteins but bacteria have
    condensin protiens
  • Asexual reproduction
  • Binary fission, budding, fragmenting, spores

45
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46
  • Plasmids
  • Small DNA molecules
  • replicated independently
  • nonessential information
  • used in genetic engineering biotechnology

47
  • Ribosomes (70S)
  • Composed of large and small subunits
  • made of riboprotein and ribosomal RNA
  • differ in density from eukaryotic ribosomes
  • target for antimicrobials

48
  • Inclusions
  • Metachromatic granules
  • Polysaccharide granules
  • lipid inclusions
  • sulfur granules
  • carboxyzomes
  • magnetosomes
  • Gas vesicles

49
  • Endospores
  • Resting cells
  • Highly resistant
  • Heat, desiccation, chemicals and UV light
  • Not reproduction!

Endospore producers include Clostridium and
Bacillus
50
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