Microbes

LIVING

microorganisms

Simple cells

Prokaryotes

Archaea

Bacteria

Chapter 3
Structure

Cell Membrane

-regulates the entry
and exit of substances
-*transport and
receptor proteins*

Plasmid DNA

-Contains genes
resistant to
antibiotics

Ribosomes (70s)

-cannot survive
without protein
synthesis (70s)

Chromosomal
DNA

-basic genome
-all contain this DNA

Cell Wall

-PTG
-specific to bacteria
-protection against lysis
-essential for survival

Gram-Positive

-thick PTG wall
(many layers)

Gram-Negative

-thin PTG wall
-outer membrane
-LPS-endotoxins
-porins

Appendages

Flagellum

Mobility
and
enables
chemotaxis

Fimbriae

attachment to
surfaces

Sex Pilus

Conjugation
(transfer of
plasmid DNA)

Chapter 4
Growth

Binary Fisson

splitting into 2

Generation Time

amount of time
it takes to double

Calculating Growth

#=initial # * 2^(#of doublings)

Factors Affecting Growth

Temperature

psychro/meso/thermo

Oxygen Requirements

Obligate Aerobe

MUST have oxygen

Contain enzymes
to detoxify

Facultative Anaerobe

"make do" without
oxygen but grow
better with

contain enzyme
to detoxify

Obligate Anaerobe

must have NO
oxygen (poisoned
by oxygen)

does NOT contain
enzyme to detoxify
-endospores survive

Aerotolerant Anaerobe

indifferent to
oxygen
-doesnt care
either way

contain enzyme
to detoxify

Microaerophile

needs small
amounts of
oxygen

contain enzyme
to detoxify
(only have a
few enzymes
to break down
oxygen)

pH Requirements

Neutrophiles

grow best
pH~7

Acidophiles

pH <5
(low pH)

Alkaliphiles

pH >8
(high pH)

Salt

Halotolerant

small amount
of salt

Halophiles

require salt

Extreme Halophiles

require high
salt

Nutrients

Versatile

can make
things from
scratch

Fastidious

cannot make
things from
scratch

Expectations

Mycoplasma -->
lack cell wall

Myobacteria -->
waxy, lipid cell wall

Endospores -->
bacillus and clostridium

Chapter 20
Part 1

Selective Toxicity

kills microbes
--> low toxicity
to humans

Broad Spectrum

effective against
>1 group of bacteria
**kills microflora

Narrow Spectrum

target a specific
group
**must know
exact target

Complex cells

Eukaryotes

Algae

Autotrophs
-cell wall made
of cellulose
-toxins--> paralytic
shellfish poisoning

Fungi

Morphological Forms:

Yeasts
-unicellular

Moulds
-multicellular

Mushrooms
-multicellular
-reproductive
structures:

**obtain nutrients
by secreting
digestive enzymes

Heterotrophs
-cell wall CHITIN
-Ergosterol in cell
membrane
-target for antibiotics

Cause Human Illness

1) Intoxication
-toxins poisonous

2) Allergy/Asthma
-hypersensitivity

3) Mycoses
-fungal infections
grow on/in body

Dermatophyte
--Ringworm,Jock itch

Candida (mucous
membrane)
--vulvovaginal, oral thrush

Lung infection
--**worse on
immunocompromised

Protozoa

unicellular, heterotrophs
-lack cell wall
-motile

Malaria
--Mosquito vector

Giardiasis
--fecal-oral-cyst form

beaver fever

Toxoplasmosis
--cysts ingested

pregnant women kitty litter

REMEMBER:
protozoan cysts can
withstand stomach
acid
**essential for fecal-oral route

Helminths

Worms

1) Ingestion

feces-->pinworm, asariasis
raw meat-->tapeworm

2) Burrow through skin
(bare feet, poor sanitation)

Schistosomiasis

3) Insect Bites
transmit tiny
thread like worms

Elephantiasis
--mosquito

River Blindness
--black fly

NON-LIVING

Acellular

Viruses

"obligate intracellular
parasites"
-need host cell for
protein synthesis machinery
-very small
-Structure:

Genome Replication:

DNA -->
DNA polymerase

DNA will NOT
make mistakes

RNA -->
RNA replicase

RNA/Retro rapidly
undergo antigenic drift

mechanism for
variation in viruses
(accumulation
of mutations)

Retroviruses --> reverse
transcriptase to transcribe

Infections

Acute:

rapid onset
short duration

Persistent

years of lifetime

Chronic

virons constant
release in low
levels = productive

Hep. B
HIV

Latent

periods of latency
with potential for reactivation
to productive infection

Herpes (cold sores)
Varicella zoster
(chicken pox
--shingles)

Viroids

-small single
strand RNA
-NO protein coat
-cause disease in
plants

Prions

-one single protein
-NO nucleic acid
-Transmissible
Spongiform Encephalopathies (TSE)
----slow fatal neurodegenerative
disease
***brain tissues develop holes

scrapie --> goats
mad cow and kuru --> people

Both -/+ have:
-Glycocalyx
(sugarshell)
-Capsule-compact layer
*protection from phagocytosis*
-Slime Layer-runny, unorganized
*contributes to biofilm*

Hyphae-multicellular
filaments, divided by
septa

Naked

Enveloped