MICROBIAL GROUPS
Range of Microorganism
eukaryotes
fungus
characteristics
multicellular and multinucleated (except yeast)
spore-bearing organisms
absorptive heterotrophs
saprophytes
rigid cell wall (chitin)
no chlorophyll
types
chytrids (Chytridiomycota)
Neocallismastigales
obligate anaerobe
decompose cellulose
breakdown lignin deposits into smaller species
zygote (Zygomycota)
sac (Ascomycetes)
club (Basidiomycetes)
Feeding forms
Saprobic heetrotrophs
feed on dead or decaying organic matter
Parasitic heterotrophs
feeding on living hosts
Mutualistic heterotrophs
feeding of /living of without damaging the host --> host & fungi benefit
reproduction
sexual
condition change (unfavourable)
generate diversity diversification
division of parent cell
production new buds (yeast)
spore production (mitosis and cell division)
asexual
condition stable
maximise production
genetic diversitification (less urgent)
morphological and ecological grouping
mycorrhizae
mutualistic ( plant root & fungi)
benefits
plants
increase surface area
increase growth potential
fungi
feeding from tissues of the plants
lichen
association of fungus & photosynthetic symbiont --> thallus
involve ascomycete fungi (mostly) and basidiomycete
ecological role
primary succession
making abiotic world habitable to biotic world
sensitive environmental indicators
mycobiont
protection from sunlight and dessication
absorb nutrients
photobiont
synthesize organic nutrient from CO2
ecological impacts
decomposers
reduce complex polysaccharides & proteins
recycling carbon, nitrogen, & other elements to ecosystem
modify habitat
lichens - inhabit hospitable places --> make habitat suitable
spoilers
decompose food , wood, etc
improve plants growth
eg: micorrhizae
pathogens
causes athletes foot, ringworm, &yeast infection
produces natural carcinogen and aflatoxin
harmful to organism
slime/water molds
characteristic
resemble fungi (lifestyle & appearance)
differents in cellular organization,reproduction and life cycle
divisions
Acrasiomycota
celular slime molds
individual amoeboid cells
feed phagosytically
plentiful of food --> divide by food & cytokinesis
oomycota
true fungi in appearance => finely branced filaments (hyphae
sexual reproduction
decomposers in aquatic system
Myxomycota
plasmodials (acellular)
multinucleated
phagocytosized dead materials
saprophytes
glistening, viscous masses of slime
habitat
terrestrial habitat eg. soil, decaying wood, dung and etc
ecological function
engulf bacteria (predator)
decomposer & consumerin ecosystem
recycling of nutrients
cause disease in plantseg. tobacco plants, potatoes, grapes
algae
characteristic
simple "aquatic plants"
diffrences with other photosynthetic eukaryotes
lack vascular conducting system
simple reproductive structure
lack true leaves, roots, flowers & etc
photoautotrophics
distribution
primarily aquatics
Planktonic
suspended in aqueous environment
phytoplankton
benthic
attach & living on bottom of water
Neustonic
at water atmosphere interface
terrestrial
moist, rocks, trees, soils
endosymbionts in protozoa, worms, corals, fungi (lichens)
classification
cell wall
flagella number & location
chlorophyll & pigments
habitat
reproductive structures
nutrition
autotrophics
photoautotrophics
heterotrophs
chemoheterotrophs
Subtopic
reproduction
asexual
ex
thallus breakup --> fragmentation parts --> new thallus
spores
nor,mals vegetative cells or sporangia
flagellated motile spores = zoospores
non-motile spores = aplanospores
binary fission
nuclear division --> division of cytoplasm
sexual
oogenia (eggs) + antheridia (sperms) --> zygote
ecology
seaweed eg: Rhodophyta & phaeophyta algae
protozoa
characteristic
motile eucaryotics unicellular protist
nutrition
chemoheterotrophs
holozoic
solid nutrients --> phagocytosis --> cytostome
saprozoic
soluble nutrient --> pinocytosis --> diffusion, carrier mediated resonses
reproduction
asexual : binary fission
nucleus --> mitosis
cytoplasm --> cytokinesis
sexual: conjugation
habitat
moist habitat ( fershwater /marine)
some terrestrial (soil)
ecoological role
in marine food chain
eg: zooplankton ingest phytoplankton and bacteria
interaction with higher microorganism
parasitic relationship ( harm to host )
sporozoans: Plasmodium causes malaria
mutualistic relationship eq : with ruminants
degardation of fibrous plants materials
acts as barrier to passage of pathogens ( digestive tract of ruminant)
prokaryote
bacteria
characteristic
various morphology
cellular organizations
DNA not enclosed in membrane
no other membrane compartments
genome 1/1000 smaller than eucaryotic genome
reproduction
binary fission
shorter generation time
quick evolution
higher mutation rate
nutrition
photoautotrophs
chemotrophs
autotrophs
heterotrophs
ecological function
recycling of chemical compounts
convert inorganic materials to organic materials
convert organic materiaks to CO2
symbiotics relationship
Interactions: commensalism, parasitism, mutualism eg: N fixing bacteria provide source of N for plants
environmntal applications
bioremediations
remove dentrimental pollutants from the environment
viruses
characteristic
obligate intracellular parasites
cannot replicate outside the cells
presence of either DNA or RNA
inability to reproduce independent of cells
inability to carry out cell division as procaryotes and eucaryotes
viral replication
utilize host machinery & metabolism to reproduce
steps
attachment/ absorption = virus attached ti receptors on host cell walls
penetration = nucleic acid of the virus moves into cytoplasm of host cells
replication = virus induces host cell to synthesize components for its replications
asembly = newly synthesized viral components are assembled
release = assembled viruses are releaed
ecological function
mostly disease causing in human, animals & plants
eq HIV, smallpox, herpes simplex
biological walfare
Main topic
Main topic
Main topic
General Considerations of Microbial Features
microbial size
advantages of larger cell sizes
greater adaptability
gerater storage of food materials
motile organism --> greater speed attained
disadvantages of larger sizes
reduce ratio of surface to volume ratio
reduce activity related to cell membrane
effect on microbial size on velocity of cells
larger organism, settle > rapidly
smaller organism - suspension
clumps --> settle more raidly
startegy larger organism to counteract tendency to fall
eg: flagellated algae -swimming upwards
microbial cell structure
genetic informations
procaryotic cells
lying free in the cells
single closed loops of dsDNA
transcription & tarnslations, protein synthesis can occur simultaneously
part of the genome is transfered
recombinant process: conjugation, transduction
eucaryotic cells
DNA bound to basic proteins
enclosed by membrane
transcription --> migration of mRNA into cytoplams --> translation
mitosis and meiosis --> daughter cells have correct coplement of genetic info
recombinant process: mainlty sexual reproduction
cell membrane
importance
permeability properties
maintaining levels of nutrients metabolites. slats, pH in the internal evironment
site of nutrient, ion, & protontranslocating systems
procaryotic cells
semi-permeable
site of energy-yielding terminal respiratory system
eucaryotic cells (ptotozoa)
outgoing axtivuty
outer cell membrane fused with membrane systems within the cell
ingoing activity
organism wiyhout rigid cell wall --> invagination of cell membrane
surface layers
eg cell walls
determine
shapes
resistants to osmotic stress
procaryotic cells
peptidoglycan --> site of action of penicillin
components of cell walls --> determine surface properties of ce;ll walls
synthesis & lysis at septal region of dividing cells --> determine formations of chains /clumps
eucaryotic cells
prevent phagocytosis 7 amoeboid movements
rigidation
penetration of host tissue and other substrates
less osmotic damage
motility
procaryotic cells
major by using flagellum
eucaryotic cells ( algae, protozoa, fungi, zoospores)
major by using falgellum, cilia,amoeboid movements
microbial cell replication
procaryotic cells
smaller in size , shorter generation time
binary fission
new cells --> uniform in size
separation of daughter cells --> autolytic enzymes
eucaryotic cells
method
budding
eg: yeast --> smaller buds compare to maximum buds = 20
sporulation
eg: fungi --. smaller than parent cell, many spores at one cycle
cell nutrition
determine microbe's habitat
major elements required : C,H, N O P, S
cell behaviour
chemotaxis
towards favourab;e chemical environment
bacterial chemotaxis
presence of chemoreceptores
chemoreceptors: proteins on cell wall /membrane
+ve chemoreceptors : attractants
-ve: chemoreceptors: repellants
function:
to sence presence /absence of attravtants/repellents
to sence its concentrations
bacteria --> sence concentration through gardient of repellent/ attractants
movement in isotrophic solution of attractant
swims for short periodin straight lines, tumbles & resumes swimming in different straightlines. similar pathlength
movements inincreased concentrations of attractants
pathlenght of length increased, frequency of tumbles decreases
movements in decreased concentration of attractants
pathlebgth of runs decreased, frequency of tumbles increased
movement in increased concentartion of repellant
pathlength of runs decreased, frequency of tumbles increases
movement in decreased concentarion of repellant
pathlength of runs increases, frequency of tumbles decreases
summary: favourable concentration of gradient --> tumbling is supressed and vice versa
eucaryotics microbes
rare among fungi, protozoa and algae
if occur, morecomlicated e.g slime molds
for 'social lives" eg cellular lime molds --> scarcity of food --> release chemical --> attract to frm assemblages of many cells
sexual attractants for sexual reproductions
phototaxis
move toward or away from light
control the localized distributions of organism in habitats
photoreceptors & photosynthetic pigments
photoreceptors --> respond to change in light intensity