Hydrogen Bonding

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Hydrogen Bonding Van der Waals
Forces Hydrophobic Forces pH scale and
Buffers Biomolecules
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Chapter 4 Microscopy and Cell Structure Resoluti
on Limits to Resolving Power Refractive
Index Aberration Early lenses were
generally not homogenous glass and had variable
refractive index across their surface, leading to
distortion
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Types of Microscopes Brightfield Phase
Contrast Differential Interference Contrast
(DIC or Namarski) Darkfield Fluorescence Co
n-Focal Transmission EM Scanning
EM Atomic Force Microscopy (AFM)
Light
Electron
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Principal of DIC (Differential Interference
Contrast) OR Phase Contrast microscopy
Highligts Edges Surfaces of objects
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Fluorescence Microscope Optic Train
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Microscope Comparison (Lens Trains)
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TEM vs. SEM TEM see
internal structure can go to very high
resolution --- down to about 5 nm directly
(further with image averaging technique) ---
down to about 0.2 nm (2 angstrom) with
electron crystallography cannot see surface
features separately see entire thickness of
sample SEM see surface features only can
do elemental analysis of scattered
electrons lower resolution than TEM (around
100-200 nm) sample preparation more difficult
(but generally fewer artifacts)
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Atomic Force Microscopy (AFM)
Advantages Range of resolutions Live
specimens Cost Disadvantages Image
quality Time consuming
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Prokaryotic Cell Structure Cell
Shape Rod/Bacillus Bent Rod/
Vibrio Spirillum (rigid helical shaped
cell) Spirochete (flexible spiral cell,
contains a flagellum between the cytoplamic
membrane and outer membrane) Multicellular
Prokaryotes actinobacteria form extensive
networks of filaments that are all
cytoplamically contiguous (although there is
some barrier to free movement of
material) filamentous cyanobacteria also form
filaments, in some cases with cellular
specialization Also keep in mind that most
bacteria live in communities
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Cell Division Fission (generally
symmetrical) Budding (distinctly
asymmetrical) Fragmentation Internal
Structures DNA Bacterial Chromosome (one
DS molecule, haploid) Plasmids (replicate
independently of chromosome) Transformation
Conjugation Transduction Ribosomes (60 S)
rRNA Protein, involved in translation Linked
transcription translation common in
prokaryotes Gas vesicles Surrounded by
protein sheath, used for buoyancy Storage
particles (Store nutrients and essential
elements) Glycogen/ Starch Poly-B-hydroxybutry
ic acid (PHB)
Horizontal Transfer