Lecture 1 - Morphology and Ultrastructure Flashcards
What constitutes a species (5 things)
- Mating constraints (classical)
- Visible characteristics (Gram, shape, spores)
- Metabolism
- Surface structures
- Molecular Relatedness
Biochemical tests can assess relatedness only if…
the cell is metabolically active
Five tools for assessing relatedness
- Biochemical tests
- Numerical taxonomy
- DNA optical mapping (restriction digest)
- Serotyping
- Direct gene sequence comparisons
Optical map assembly involves _____ DNA molecules on a glass chip
linearized
Serotyping (strain typing) involves what 4 characteristics?
- Antigens
- Antobiotic/phage sensitivity profiles
- Toxin production
- surface molecules
6 important bacterial phyla
- Proteobacteria (a, ß, g, Σ)
- Chlamydiae
- Bacteroidetes
- Actinobacteriae (Myco, coryne, Actinomyces)
- Spirochaetae (Trep, Lepto, Borrelia)
- Firmicutes
Mycoplasma cell shape
pleiomorphic (and small)
Mycoplasma energetics/metabolism?
What does its membrane require
Obligate intracellular parasites
Cholesterol
Mycoplasma does not contain a _____, only a ________.
No cell wall
only a membrane
Various archaea shapes
cocci, rod, spiral, others
Two types of energetics found in archaea
Lithotrophs, heterotrophs
Three energetic properties of archaea
- many extremophiles
- some produce methane
- protein synthesis resembles eukaryotes
Archaea envelope – it does not have ______ but has a ________
No peptoglycan *
Has a cell wall
**pseudo-pg, polysacch, protein
Major difference in archaea lipids
Ethers (Other life has esters)
The lipids also have** Branched Isoprene chains**
(instead of unbranched fatty acids)
Prokaryotes reproduce via ____. They have a _______ chromosome usually.
binary fission
Single circular chromosome
Cytoplasm of prokaryotes contains….
membrane invaginations
Specific membrane structures of prokaryotes
Mesosomes
Phycobilisomes, chromatophores
Cytoplasm of prokaryotes contains what?
Inclusion bodies (insoluble polymers, poly beta-OH butyrate, starch, glycogen, sulfur, polyphosphate granules)
Somal bodies (protein-bound vesicles, gas vesicles, magnetosomes (membrane-bound), carboxysomes)
Bacterial chromosome is…. (three properties
- anchored to membrane
- highly folded (not histones)
- few thousand genes
Important functional sites in bacterial cytoplasm
Enzymatic reaction centers
(reaction centers depend on DNA, mRNA and protein localization)
Plasma membrane can be made more fluid by…
Lowering temp
Shorter or more unsaturated fatty acids
Phosopholipid bilayer does not contain
sterols
(except mycolic acid)
Bacteria do not perform
Endocytosis
*Need transporter molecules
What is the Rocker-Switch mechanism?
external and internal binding sites for transported solute
and a “bottleneck” that is sometimes a selectivity filter
Bacteria require _____ to export proteins such as ____ and ______
Secretory systems
hydrolases, toxins
Four steps to gram stain
Crystal Violet
Iodine
Alcohol
Safranin
PG backbone made of
GlcNAc - MurNAc linked beta 1-4
C6 O-acetyl MurNAc is resistant to
lysozyme
PG side chain made of
tetrapeptide
*can vary
Differences in PG side chain among types of bacteria
G- usu. have DAP at #3
G+ usu. have lysine
PG pentapeptide cross bridge is only in…
G+
Two molecules in glycan chains of PG
NAG and **MURNAc **(N acetylmuramic acid)
Tetrapeptide uses what weird molecules?
D amino acids
6 steps in PG synth
- Pentapeptide side chain is added to UDP-NAM
- UDP-MurNAc-5aa is then transferred to bactoprenol, NAG is added
- Bactoprenol is phosphorylated and flips sides
- New monomer is removed from BP and added to a space in wall by transglycosylation
- Transpeptidation (5th Ala is lost)
- BP is Dephosphorylated and flips again
LPS is in what cell type?
Gram -
LPS constituents
- O antigen
- Core polysaccharide
- Disaccharide diphosphate
- Lipid A
- Fatty acids
Synthesis of LPS (3 steps)
- Core (monosaccharide) added to lipid A on Inner surface of inner membrane – Lipid A flips to periplasmic space
- Repeat unit is made in cytoplasm and carried to Periplasmic space by bactoprenol (and added to lipid A core)
- LPS moves to Outer membrane via bridging proteins
Bacterial species may alter what part of LPS?
O antigen
these define SEROTYPES (strains)
____ lack O antigen, and instead produce variant form of LPS called ________
Neisseria
Lipooligosaccharide
Bacteria contain polysaccharide capsule (except ______. What does it have instead?)
Bacillus anthracis
It has poly D-Glu
Purposes of capsule (glycocalyx)
- Adhesion to surfaces (Strep mutans – uronic acids)
- Anti phagocytic (Strep pneumoniae)
- Immune mimic (NmB, EcK1 – sialic acid)
Function of Pili/Fimbriae
- Hold together during conjugation
- Attach cells to surfaces (Streptococcal M protein is a minor protein at tips of pili)
- Antigenic - cells can vary antigens to evade host defenses (antigenic variation in N. gonorrhoeae)
- Motility (twitching… alternate extension and retraction)
Flagella structure
Filament composed of flagellin*
*H antigen
Location of flagella is…
species specific
How does locomotion by flagella occur?
repulsion of charges from **proton flow ** through Mot A/B proteins
What is a C ring?
switch that allows rotation to change direction
Conformations of C ring
- CCW = cell swims
- CW = cell tumbles randomly
this allows chemotaxis, a sensing of chemical gradients TEMPORALLY (not spatially)
What are S-Layers? Who are they especially prominent in?
Single crystalline protein that surrounds some cells
(esp. prominent in Archaea)
Function and characteristic of S-layers
(one of each)
- Molecular sieve (anti-complement)
- Variations in lattice arrangement are characteristic of the species
Flagella filament (propeller) is connected at the ______
Hook
(universal joint)
