Microbio Exam 2

Ploidy and Mode of REproduction in Eukaryotic Microbes

Haploid or Diploid

Asexual or sexual

Ploidy and mode of reproduction of prokaryotic microbes

Haploid

ASexual

Binary fission, Budding, Filamentous

Binary fission

1) Cell preps division, enlarging cell wall, plasma membrane, and overall volume
2) septum grows inward as newly replicated chromosomes move to opposite sides

3) Septum synthesized through cell center

4) Some species seperate while some may remain attached

Budding

Daughter cell grows in an outgrowth

Filamentous

Streptomyces, forms multinucleoid filaments that divide to form uninucleiod spores

oriC

Origin of Chromosomal replication, a specific DNA sequence where replication begins

ter

Terminus is where two replication forks meet and DNA replication ends

Stalk

Present in C. Crescentus, where a sessile stalked cell attaches to a hard surface and replicates a flagellated swarmer cell

Partitioning System components

ParA and ParB Proteins

parS chromosomal region

parS homolgous function

Functions as a centromere and sits near the oriC in C. crescentus.
Directs segregation of two daughter chromosomes

ParB

First binds to parS and then other ParB binds downstream, cover 1ks of basepairs

Partition Complex

Composed of ParB bound to parS
Found in 70% of 400 sequenced bacteria

ParA

Guides on of the Partition complexes to pole of cell opposite of stalk

Relay, passed from one ParA to next

Gradient concentrations, where gradient increases towards poles
PolA polymerizes and attaches to ParB, depolymerizes and pulls new sister chromatid to other side of cell

FtsZ role

Cytoplasmic protein that polymerizes to form the Z Ring

Z Ring site of formation

Located by MinCDE

MinCDE

A complex of free proteins, polymerize and depolymerize. from one side to another. FtsZ cannot be where MinCDE is located, so it settles in the center

Inhibits Z-ring formation anywhere but center

FtsZ membrane attachment

Attached to cell membrane with FtsA(nchoring)
FtsA is integral

Peptidoglycan Synthesizing Enzymes

Found near FtsZ, is Transmembrane

Septum

Z Ring shrinks and constricts as FtsZ is removed

Transpeptidase

Connects amino acids from one NAM to the next in the layer

Inhibited by penicillin
AKA Penicillin binding proteins

Cell wall growth

NAM binds ot bacteroprenol, NAG binds to NAM, MurJ Flippase flips NAM-NAG to opposite sides

Inserted into peptidoglycan

Autolysins

Self lysing, break bonds between NAM and NAG to make room for new units to grow cell wall

Penicillin and cell growth

Inhibits formation of Gly bridge on S. Aureus and Peptide bond of E. COli

May hyperactivate autolysins

VAncomycin

Inhibits removal of terminal alanine

Bacitracin

Inhibits bactoprenol

UDP

Used in bacteria to activate sugar

New peptidoglycan location

Found near FtsZ

Growth in bacteria refers to

Increase in both cellular constituents

Growth Curve X and Y

Log # of Viable Cells, Time

Phases in order

Lag

Log

Stationary

Death

Longterm stationary

Lag

Preparing for replication, translating protein and copying DNA
No numbered growth

Results from:
Placing bacteria from stationary/death into fresh medium
Exponential to medium of different chemical composition (Glucose→Lactose)

• Biphasic growth, KIA can help identify

• Easy sugar first to comple sugar (Glucose to lactose

Rich to poor culture (medium shift)

DOES NOT OCCUR WHEN YOU PUT EXPONENTIAL FROM MEDIA A TO MEDIA A

KIA

Medium allowing you to identify if a bacteria uses glucose or and lactose
Glucose-bottom yellow
Glucose and lactose-whole testtube yellow

Log/Exponential

Replicate as quickly as possible

• Healthiest

• Prokaryotes, faster than euaryotes

• Smaller cells faster

Vibrio cholerae grows in 7 minutes

Population is not uniform

Turbidity and, therefore, population can be extrapolated by using a spectrophotometer

Stationary Phase

Stop replication, run out of space or nutrients

Metabolically active

No translation and transcription
The viable cell # is constant

Death Phase

Used up all nutrients or excretion changes chemical environment, and this kills cells.
Programmed Cell Death: Try to fix DNA with SOS response, if unable, DNA is broken into pieces, peptidoglycan and cell membrane broken. Food is left over for the survivors

Viable but not culturable (VBNC): Living cells that don’t reproduce in the media theyre in. Colonies dont form, more colonies than is seen. Can be done by E. Coli O157 H7, Vibrio Cholerae, Listeria monocytogenes

Long Term Stationary Phase

Evolution can occur

Mutations arise as bacteria adapt to new environments.
May contain mutant colonies

Growth Advantage in stationary Phase

GRowth and death and changing of microbiome

Milk Spoilage: Lactic Acid→Fungi→proteolytic bacteria

Measurement and Growth Rate and Generation Time

Only works for binary fission during exponential growth

g

Generation time, varies between species/environment

k

growthrate constant (k)

generations/hour

Larger the number, the faster the growth

n

generation number

N_t

total final cell number

How is N related to n

N_t=2ⁿ

Calculate population time at t given initial population and number of generations in time t

N_t=N₀×2ⁿ

calculate growth rate constant given generation doubling time

k=1/g

Calculate growth rate constant given number of generations in time t and time

k=n/t

calculate k given N_t , N₀ and t

k= (logNt-logN0)/0.301*t)

calculate n given log Nt and N0

n=(log Nt - log N0)/.301

Calculate g given k

g=1/k

calculate g given n

g=t/n

calculate g given t Nt and N0

g=(0.301*t)/(logNt-LogNo)

log of 2

0.301

Extremophiles

Growing in extreme environments, Archaea

Osmolarity most organisms grow in?

Hypotonic environments, water rushes in

Hypertonic

Rushes out

Isotonic

Net zero

Contractile vacuole

Present in eukaryotes

Mechanosensitive channel, open to release pressure

Present in Amoeba(circle), and Paramecium and Euglena(stars

Compatible solutes

Present in cells in hypertonic environments. Help to increase cell solute conc.

Compatible solutes because they dont bind to enzymes and cause harm

Nonhalophile

Do not like salt
E.coli

MSA

Salt Agar, contains salt, allows differentiation for salt tolerance

Halotolerant

Tolerate some salt, prefer no salt

S. Aureus

Halophile

Only live in lightly to moderately salty environments
V. Cholerae

Extreme halophiles

Only live in SUPER salty environments

Halobacterium spp. is an archaea, need to touch with salty loop

Osmotolerant

Higher salt concentrations lower available water
All domains of life
Nothing can grow below 0.6 Aw

Acidophiles

Like acidic environments, 0 - 5.5 pH

Archaea

Neutrophiles

Like neutral environments 5.5-8 pH
Bacteria, Protists

Alkaliphiles/Alkalophiles

8-11.5 pH
Marine microorganisms

Microbial internal pH

Normally near pH 7, neutral, die if below 5.5/5.0

Acidic Tolerance Response

Pump protons out; some synthesize acid and heat shock proteins that protect proteins

Helibacter Pylori

Can live in the stomach and can result in gastric ulcers. They synthesize Urease, produces ammonia and damages gastric mucosa, and neutralizes acidic pH.
Stomach cancer

Microbial temperature regulation

Are unable to regulate internal temperature

Cardinal Growth Temperatures

Minimum, optimum, and maximum
Distance between minimum and maximum is 30-40 degrees celsius

Psychrophiles

Love cold, in the negatives
Icecaps, bottom of ocean

Psychrotolerant

Tolerate cold
Ex. Lysteria monocytogenes

Mesophiles

Like body temperature

Escherica coli

Thermophiles

Like heat

Hyperthermaphiles

Close to 100 degrees

Psychrophiles adaptations

Proteins

• More alpha helices, fewer beta sheets

• More polar, less hydrophobic amino acids

Fatty acid chains

• More unsaturated and shorter

Compatible solutes to decrease freezing point

Hyperthermophiles

Protein structure

• Presence of chaperones and HSP

• more H bonds and proline

Fatty acid chains

• More saturated, branched and higher molecular weight

Most are certain species of archaea

• Monolayers and ether linkages

Histone-like proteins stabilize DNA

Thioglycolate Tubes

Used to measure oxygen tolerance of bacteria

Have a gradient of oxygen in media

Pink(oxic) to clear(anoxic)

Obligate Aerobe

REquires oxygen

Microaerophile

Prefer oxygen at a lower concentration than atmospheric concentration (5% in atmosphere)

Facultative anaerobe

Grows throughout the test tube, grows better at the tube, cloudiness through out the tube, more at top

Aerotolerant anaerobe

Equal distribution throughout

Strict anaerobes

Strictly grows without oxygen, need to be ground without oxygen

Reasons for differences for Oxygen tolerance

Reactive Oxygen Species
Superoxide O2
Hydrogen Peroxide H2O2
Hydroxyl Radical OH

Protective Enzymes

Superoxide dismutase (SOD)
Catalase
Peroxide

Reaction w SOD/Peroxidases/Catalases

O2→O2*→Superoxide dismutase→ H2O2→Peroxidases and Catalases→H2O

Obligate Anaerobe Enzyme

+SOD
+Catalase
+Peroxidase

Microaerophile Enzymes

+SOD
+/- Catalase

+Peroxidase

Facultative Anaerobe Enzymes

+SOD
+Catalase
+Peroxidase

Aerotolerant Enzymes

+SOD
-Catalase
+Peroxidase

Strict Anaerobe Enzymes

-SOD

-Catalase

-Peroxidase

Peroxidase vs Catalase

Peroxidase uses NADH_2→NAD and produces 2 H2O
Catalase only uses H2O2 and produces 2H2O and O2

Barotolerant

AKA Piezophilic, increase in unsaturated shorter fatty acids

Halmonas salaria- Gram-negative bacteria that requires 14,794 psi, or 1006 ATM to grow
Grow at bottom of Ocean

Ionizing radiation

Disrupts chemical strcture, X-Rays and gamma rays
Short wavelength and high energy
Single and double stranded DNA breaks
generates free radicals OH*
Deinococcus radiodurans, a tetrad where they fix eachothers chromosomes

Nonionizing raditiation

Ultraviolet radiation

longer wavelength, lower energy
thymine dimers
Sterilization

Visible light

Cyanobacteria absorb wavelengths and convert to useable chemical energy

Violet penetrates 100m
Blue penetrates 270m
Green penetrates 150m
Yellow pens 70m
Orange penetrates 40m

Chlorophyll

Primary pigment, converts light to energy, absorb white at different wavelengths

Phycocyanin or phycoerythrin

Accessory pigment, light absorption