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118 Cards in this Set

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Microbial Cell growth (picture)

Most prokaryotes duplicate themselves by _____/_____.

Binary/fission

There are more than _____ chemical reactions that occur to duplicate a cell.

2000

What is the shortest known microbial doubling time?

Shortest known microbial doubling time is 6 minutes

How long does it take microbes in sea sediments to double?

Microbes in sea sediments may take decades to double

How long does it take E. Coli to double?

E. Coli doubles about every 20 minutes

The general process of binary fission in a rod-shaped prokaryote. (picture)

Microbial growth is _____ - the number of cells double per unit time

exponential

Define exponential growth

the number of cells doubles per unit time

The number of cells in a bacterial culture is a function of what?

the number of cells in a bacterial culture is a function of 2 (one parental cell gives rise to two daughter cells)

What is the number of cells in a bacterial culture a factor of two?

One parental cell gives rise to two daughter cells

Population growth formula

In the population growth formula what does N, Nknot, and n stand for?

N = final cell number, Nknot = initial cell number, n = number of generations

From the population growth formula what other equation can you derive?

Define Lag Phase

Time before exponential growth starts. Cells adapt to the medium. Resynthesize essential components for growth.

Define exponential phase

Time of exponential growth. Influenced by environmental conditions

Define Stationary phase

Growth stops. Due to limiting nutrients or buildup of waste. Basic cellular functions continue

Define Death Phase

Cells die off

Do bacteria get 'old'?

YES! - the cell that inherits the "old pole" exhibits a diminished growth rate, decreased offspring production, and an increased incidence of death

"aging" of cells (picture)

Why do bacteria age?

Asymmetric division of materials in the cell

Asymmetric division of materials in the cell (picture)

What are the four main environmental factors affecting microbial growth?

1. Temperature


2. pH


3. Water availability


4. Oxygen

What are the 3 cardinal temperatures and define them

Minimum temperature - below this temperature growth no longer occurs


Optimum temperature - growth is most rapid


Maximum temperature - above this temperature growth is not possible

The ______ temperature is always near the maximum temperature

Optimum

Cardinal temperatures (picture)

The absolute values of the cardinal temperatures varies greatly between microorganisms (T/F)

True

What is the typical growth range of most microorganisms?

Typical growth range 30-40C

Much of the earth is hot. (T/F)

False. Much of the earth is cold

What is the average temperature of oceans?

oceans have average temperature of 5C

In polar regions there are large areas of land that are frozen much of the time (T/F)

True

Define Psychrophiles

Optimal growth temperature below 15C

What are two examples of psychrophiles?

Snow algae - grows on the surface of snow in permanent snow fields


Chemoorganotrophic bacteria found in polar ice

Where are they searching for life (a very cold place on Earth)?

Search for life in Lake Vostok

Define Psychrotolerant

Can grow at low temperatures, but optimum temperature is between 20-40C

Psychrotolerant microbes are less common than psychrophilic organisms. (T/F)

False. More common than psychrophilic organisms

Where might psychrotolerant microbes live?

Soil and water in temperate climates

On what might psychrotolerant microbes live on?

Found on refrigerated food - meat, dairy, cider, vegetables, fruit, etc.

What type of microbes can be psychrotolerant?

bacteria, fungi, algae, and protozoa

What are the characteristics of enzymes that function best at cold temperatures?

Have more alpha-helices and less beta-sheets


Have more polar and less hydrophobic amino acids

What molecular adaptations to membrane lipids do cold living microbes have?

Membrane lipids contain more unsaturated fatty acids.

What does a membrane lipid containing more unsaturated fatty acids do?

Will allow it be more fluid at low temperatures

What do cold living organisms do about freezing and requirement for liquid water?

Take advantage of pockets of liquid water even below OC

What did they find from the Vostok ice core?

A bacterial ice-binding protein from the Vostok ice core

Define Thermophiles

optimum growth temperature is above 45C

Where do Thermophiles live?

Grow in hot springs where the water has cooled slightly

Define Hyperthermophiles

optimum growth temperature is above 80C

Where do Hyperthermophiles grow?

Grow in hot springs near boiling point of water


Grow around deep sea hydrothermal vents about 100C

Hyperthermophiles include a large variety of ______ organisms - including both _____ and ______

prokaryotic


Bacteria


Archaea

What are the difference in proteins for thermophily?

increased number of ionic bonds between amino acids


Densely packed highly hydrophobic interiors


Chemicals (e.g. diglycerol phosphate) produced to stabilize proteins

What are the differences in lipids for thermophily?

Lipids rich in saturated fatty acids


Hyperthermophilic Archaea have diglycerol tetraethers - form a monolayer

What are the differences in DNA for thermophily?

Specialized DNA enzyme - reverse DNA gyrase - introduces positive supercoils into the DNA preventing denaturation

Define reverse DNA gyrase

Introduces positive supercoils into the DNA preventing denaturation

What is an example of life without light?

Hydrothermal vents

Archaeal membrane structure: lipid bilayer (picture)

Archaeal membrane structure: lipid monolayer

Where are hyperthermophiles on the tree of life?

Hyperthermophiles cluster near the hypothetical root of the tree of life, in both Bacteria and Archaea

What was Dr. Karl Stetter trying to do?

Looking for life in volcanoes

In 2003 what did Dr. Karl Stetter receive?

in 2003, Stetter was honored with the Leeuwenhoek Medal by the Royal Netherlands Academy of Arts and Sciences

What is the significance of the Leeuwenhoek Medal?

This award is given every 10 years to the scientist who has made the most outstanding contributions to the advancement of microbiology

All hyperthermophiles are near the root of the tree of life. (T/F)

True

Define Acidophiles

Grow best at low pH

Define Obligate acidophiles

unable to grow at neutral pH

What is the main issue with acidophiles?

Stability of the membrane is the main issue

What do acidophiles need in order to stabilize their membranes?

Need high concentration of H+ ions for membrane stability

Define Alkaliphiles

Grow best at high pH

Where do Alkaliphiles grow?

Live in highly basic environments - soda lakes and high carbonate soils

What is the main issue for Alkaliphiles?

Generation of the proton motive force is the main issue

What do some Alkaliphiles use for transport and motility?

Some use Na+ gradient for transport and motility

Some Alkaliphiles still use PMF for ATP synthesis. (T/F)

True

In both acidophiles and alkaliphiles the _____/_____ often remains near neutrality.

Intracellular/pH

What does a neutral intracellular pH prevent?

prevents the destruction of macromolecules

In both acidophiles and alkaliphiles the _____ is highly buffered.

Cytoplasm

What are the extreme limits of intracellular pH?

4.6-9.5

Yellowstone is home to what microorganism?

Sulfolobus acidocaldarius

Where does Spirulina live?

Lake Magadi in Africa. A 'soda' lake. High in carbonates. Contains Spirulina

Define Halotolerant and Halophilic Microorganisms

Organisms that can grow at high concentrations of salt

What happens to most microorganisms at high salt concentrations

Most microorganisms dehydrate and die at high salt concentrations

Define Halotolerant

microorganisms can tolerate high salt concentrations



When do Halotolerant organisms grow best?

Grow best without added salt

Define Halophilic

Microorganisms usually require Na+ for growth

Where are halophilic organisms usually found?

Often found in the ocean - 3% NaCl

How does a cell bring in water?

To bring in water a cell must increase the internal solute concentration

Cytoplasm usually have _____/_____/_____ - water _____ in.

high/solute/concentration


diffuses

In order to bring in water what does a cell need to generate?

Need to generate a positive water balance.

What does a cell do to generate a positive water balance?

Pump in ions from environment


Concentrate organic solutes

Low "water activity" must not interfere with what?

Must not interfere with biochemical processes

What are compatible solutes? (list them)

sugars, sugar alcohols, alcohols, amino acids and their derivatives, K+ ions

What color are the San Fransico Bay area salt ponds?

Red

What lives in the San Francisco Bay area salt ponds?

Halobacteria

What is the story of Owens Lake, CA?

Owens Lake was once a vast blue lake, before it was drained (by diverting Owens River) to provide the city of Los Angeles with water. Today it is a pinkish-red, dry lake bed (playa) teaming with salt-loving Archaea

How is water activity related to the food industry?

Traditional methods to control microbial spoilage, such as salting, smoking, and drying, are based on reducing the water activity of the meat


Can also apply bacteriostatic substances such as formaldehyde and phenolic compounds in smoke

Halophiles cannot grow on salted food. (T/F)

False. Halophiles can still grow on salted food!

What is Shark bay, Australia full of?

The bay is full of stromatolites, rocky formations up to 1.5 metres high which were built by colonies of halophilic cyanobacteria (the first ever oxygen photosynthesizers)

Define stromatolites

rocky formations up to 1.5 metres high which were build by colonies of halophilic cyanobacteria

Cyanobacteria are halophilic but were not the first ever oxygenic photosynthesizers. (T/F)

False. Cyanobacteria is halophilic an they were the first ever oxygenic photosynthesizers

Oxygen is lacking in many microbial habitats. (T/F)

True

O2 is poorly _____ in water.

Soluble

What happens to 02 that dissolves quickly in water?

O2 that does dissolve is quickly used up by organisms

What are some examples of O2 poor environments?

Muds and sediments, marshes and bogs, waterlogged soils, intestinal tract of animals, sewage sludge, areas deep below the earth's surface

define obligate aerobes

must grow at full O2 tensions - 21%

Define facultative aerobes

can grow either with or without O2

Define Microaerophiles

Require reduced O2 tensions

Define aerotolerant anaerobes

tolerate O2 but do not use it

Define Obligate Anaerobes

Cannot grow in the presence of O2

Oxygen classes (diagram)

What do Obligate aerobes require?

Obligate aerobes require aeration


Require shaking or bubbling air through medium

In an anaerobic culture what must be excluded?

O2

How can you make an anaerobic culture where O2 is excluded?

Tubes can be filled to the top and tightly sealed


Add reducing agent - thioglycolate (reacts with O2 in the medium)


Anaerobe jar (anoxic jar)


Gas pack replaces air in jar with H2 and CO2


Catalyst consumes O2

Why are some microbes unable to grow in oxygen?

Oxygen toxicity

Byproducts of oxygen are often highly _____.

Toxic

Why are some of the byproducts of oxygen highly toxic?

Spontaneously oxidize cellular marcomolecules


produced by photooxidation and biochemically by peroxidase enzymes


Organisms often contain carotenoids - detoxify the singlet oxygen into nontoxic forms

What are some of the toxic oxygen species produced as byproduct of reduction of O2 to H2O in respiration?

Superoxide anion (O2-)


Peroxides (H2O2)


Hydroxyl radical (OH-)

What are the enzymes that destroy toxic oxygen?

Catalase


Peroxidase


Superoxide dismutase


Superoxide dismutase/catalase in combination

Oxygen toxicity can also occur in humans. (T/F)

True

What happens if someone experiences oxygen toxicity?

Again, excess oxygen can directly damage even human cells, e.g. Pulmonary oxygen toxicity

What species lives in Mono Lake, CA?

Spirochaeta americana

Where are the four places we have been looking extra-terrestials, and why?

Mars - now dry


Enceladus - ice and water


Titan - liquid methane


Europa - sub-surface salty oceans