2. Historical
Figures
of
Microbiology
• Robert
Hook
– early
microscopes
allowed
first
descrip=on
of
microbes:
frui=ng
structures
of
molds
• Antonie
van
Leeuwenhoek
– improvements
in
lens
construc=on
allowed
first
descrip=on
of
bacteria
• Louis
Pasteur
– 1)
discovered
that
living
organisms
discriminate
between
op=cal
isomers
– 2)
discovered
biological
nature
of
alcoholic
fermenta=on
– 3)developed
vaccines
for
anthrax,
fowl
cholera
and
rabies
– 4)
disproved
spontaneous
genera=on
and
developed
methods
for
controlling
growth
of
microorganisms.
Also
developed
pasteuriza=on
and
sanita=on.
– 5)
disproved
spontaneous
genera=on
• Robert
Koch
– Kocks
postulates
• Example:
used
to
discover
microbe
(Helicobacter
pylori)
caused
stomach
ulcers
• Carle
Woese
– was
primarily
responsible
for
iden=fying
the
domain
Archaea
3. Basics
for
life
• Metabolism
– Goal
is
to
create
ATP
to
store
and
use
for
energy
• growth
• reproduc=on
• gene=c
varia=on/evolu=on
• response/adapta=on
to
the
external
environment
• homeostasis
(maintaining
internal
organiza=on
and
order,
usually
by
expending
energy)
4. Macromolecules
• Polypep=des
(amino
acids)
– building
blocks
for
enzymes
and
other
proteins
– 50-‐55%
dry
weight
of
cell
• Nucleic
acids
(Ribonucleo=des
2-‐5%;
Deoxyribonucleo=des
15-‐20%)
– DNA/RNA
cri=cal
as
storehouses
of
gene=c
informa=on
• Lipids
– Oen
found
forming
membranes
to
separates
cell
interior
from
the
external
environment
• oen
embedded
with
polysaccharides
and
polypep=des
– 10%
dry
weight
of
cell
• Polysacharides
– Sugars
that
are
used
for
structural
or
energy
storage
– 7%
dry
weight
of
cell
5. The
Domains,
Basics
• Viruses
Not
Included
– Technically,
viruses
aren’t
considered
to
be
alive
– don’t
replicate
outside
of
a
host
cell
– lible
to
no
biochemical
ac=vity
outside
of
a
host
cell
– inert
and
nonreac=ve
outside
of
a
host
cell
6. Origin
of
Life
• Lible
oxygen
in
the
atmosphere
– Cyanobacteria
began
to
oxygenate
atmosphere
at
3
billion
ybt
and
establised
an
oxygenated
enviro
at
2
billion
ybt
• Surface
of
the
planet
was
a
soup
of
chemicals
• Led
to
the
ini=al
synthesis
of
the
first
forms
of
macromolecules
• First
Microbial
Life
– In
the
1950s,
a
grad
student
named
Stanley
Miller
worked
with
his
mentor,
Harold
Urey,
to
simulate
the
“spark”
that
might
have
started
forming
organic
molecules
from
the
primordial
soup
Figure 1.12"
7. Requirements
of
early
life
• gene=c
informa=on
storage
and
the
ability
to
catalyze
biochemical
reac=ons
– Solved
by
Ribozymes
• combina=on
of
RNA
and
enzymes
• reac=on
catalyst
• gene=c
informa=on
storage
• self-‐replica=ng
• a
way
of
separa=ng
the
cell
interior
from
the
external
environment
– Use
of
Micelles
may
have
been
an
early
form
of
plasma
membrane
• Endosymbio=c
Theory
8. Modern
Life
• Double
Stranded
DNA
– provides
a
“backup
copy”
of
the
gene=c
informa=on
– more
stable
than
RNA
• Central
Dogma
– DNA
is
transcribed
into
messenger
RNA
– mRNA
is
translated
into
proteins
– other
forms
of
RNA
(tRNA,
rRNA)
are
also
important,
showing
the
versa=lity
of
RNA
molecules
for
life
processes
• How
to
examine
Microbial
Genomes
– Examining
effects
of
single
muta=ons
in
DNA
individually
– Studying
and
comparing
pieces
of
genomes
to
each
other
across
domains
