TAMU BIOL 206 Exam 3

96% of the bacterial cell is composed of which elements (10)

carbon, hydrogen, oxygen, phosphorus, sulfur, nitrogen, potassium, calcium, magnesium, and iron

Which elements are needed in gram quantities?

carbon, hydrogen, oxygen, phosphorus, sulfur, and nitrogen

Which elements are needed in MILLIGRAM quantities (1mg=.001g)

potassium, calcium, magnesium, and iron

Importance of potassium in microbial metabolism

essential to protein synthesis and membrane function

importance of calcium in microbial metabolism

cell wall and endospore stabilizer

importance of magnesium in microbial metabolism

membrane and ribosome stabilizer

importance of iron in microbial metabolism

part of the electron transport chain

Trace elements required by microorganisms are

manganese, zinc, cobalt, molybdenum, nickel, and copper (needed in ug quantities 1ug=.000001g)

Why are trace elements required by microorganisms?

they aid in the catalysis of reactions

The number of nutrients an organism must obtain to live is determined by

the kind and number of its enzymes

What happens if an enzyme is not present?

the organism is incapable of using a metabolic reaction to produce a certain substance

The organism must obtain the enzyme from

the environment (if it cannot make it)

E.coli contains how many different compounds

>5000

Does E.coli use all these compounds to synthesize this great diversity?

No, it only uses a few compounds (glucose, trace elements, H2O, and 6 others)

What does this say about the number of enzymes that E.coli has?

E.coli has alot of compounds but only uses a few

What are inorganic nutrients?

atom or molecule that contains a combination of atoms other than carbon and hydrogen

Inorganic nutrients can have carbon and hydrogen just can't have...

them together

examples of inorganic compounds

O2, CO2, and H2O

What is an organic nutrient?

A nutrient that contains both carbon and hydrogen and are usually the product of living things

Examples of organic compounds include

methane (CH4) and carbohydrates (CHO)

What environmental factors influence microbes?

temperature, pH, gas requirements, osmotic pressure, radiation, barometric pressure, and ecological associations

Environmental factors fundamentally affects what?

the function of metabolic enzymes

What are the 3 cardinal temperatures?

minimum, maximum, optimum

Minimum temperature is what?

the lowest temperature that permits a microbes growth and metabolism

Maximum temperature is what?

highest temperature that permits a microbes growth and metabolism

optimum temperature is what?

promotes the fastest rate of growth and metabolism.

What does poikilothermic mean?

Body temperature is not homeostatic, but functuates with environmental temperature

Are cardinal temperatures fixed?

no, because they are influences by environmental factors

Psychrophiles

cold-loving microbes (-10c to 20c) can grow in refrigerator, not human pathogens

Psychrotolerant

Organisms that can grow at 0ºC but have optima of 20ºC to 40ºc. grow slowly in the cold.

Mesophiles

those growing best between 20 degrees and 40 degrees celcius; the human pathogens are in this group.

Thermophiles

heat loving microbes, 45C to 80C

extreme thermophiles

thrive in very hot environments (70C to greater)

Archae are

extreme thermophiles (CM has saturated fatty acids which make it more resistant to heat)

pH is a measure of

the hydrogen ion concentration in a solution

pH is defined as

the degree of acidity or alkalinity of a solution on a 0-14 scale

The pH of pure water is _____ .

7 (neutral)

Does each species have a definite pH growth range?

yes

What is the optimum pH range for most organisms?

6-8 (acid and base can be near neutral)

The effects of pH can be related to...

the concentration of hydrogen ions in the medium and to the protection that bacterial cell walls sometimes provide.

Changes in pH can lead to what?

denaturing of enzymes/other proteins and can interfere with pumping ions at the cell membrane

Acidophiles grow at what pH?

0-5.5 (extremely acidic environment)

Neutrophiles grow at what pH?

6-8

alkalophiles grow at what pH?

8.5-12

Where is Helicobacter pylori found?

Stomach (pH 2.5)

What does Helicobacter pylori cause?

peptic ulcers, gastric and esophageal cancer

Is helicobacter pylori acid-tolerant?

no

How does Helicobacter pylori survive in the stomach?

it protects itself from the stomach by growing in protective mucus layers of the stomach

Is helicobacter pylori treatable?

yes, with antibiotics

Is oxygen an important respiratory gas?

yes

What toxic products does oxygen transform into once it is utilized?

O2, O2-, H2O2, and OH-

How do cells neutralize these toxic O2 products?

they have developed protective enzymes

If a microbe is not capable of dealing with toxic oxygen

it lacks protective enzymes, so it has to live in oxygen free environments

Aerobe

utilizes oxygen and can detoxify it

Obligate aerobes require

oxygen for growth

facultative anaerobes

utilizes oxygen but can also grow in its absence

Microaerophilic

requires only a small amount of oxygen

Anaerobe

does not utilize oxygen

obligate anaerobes

organisms that cannot live where molecular oxygen is present

aerotolerant anaerobes

do not utilize oxygen but can survive and grow in its presence

Halophiles require an environment with a high concentration of ________ for optimal growth.

salt

Osmotolerant bacteria

do not require high concentration of solute but can tolerate it when it occurs

Water activity (Aw) is a measure of what?

the water that is available for use by an organism

Aw is lowered by adding _______ to a solution

solutes

What is the relation of osmotic pressure and water activity?

they are inversely related

What happens to enzyme function and metabolism when water activity is lowered?

enzyme function and metabolism are also lowered which leads to death of the cell

Aw of water

10

Can UV light cause mutation in DNA?

yes, Thymine-Thiamine dimers which are toxic and can even kill organisms

Some organisms have which systems that can repair certain kinds of DNA damage?

enzyme systems

Can ionizing radiation be used to sterilize items?

yes

What can survive large doses of ionizing radiation?

endospores

Bacillus stearothermophilus endospores are used to test what?

Radiation ( in an autoclave)

What is hydrostatic pressure?

pressure exerted by a water column as a results of the weight of the column with each 10m of water depth

Hydrostatic pressures of >200 atm generally can do what?

inactivate enzymes and disrupt cell membrane and transport enzymes

What atm can hydrostatic pressure reach in the deep ocean?

>1000 atm

Can some bacteria still survive in the deep ocean despite high hydrostatic pressure?

yes, but these barophiles will rupture if exposed to normal atmospheric pressure

Symbiosis

A close relationship between two species that benefits at least one of the species.

Mutualism

symbiotic relationship in which both species benefit from the relationship

Commensalism

one organism benefits and the other is unaffected

Parasitism

One organism benefits and the other is harmed

example of mutualism

Lichens : an association between fungus and a photosynthetic microbe

BSL-1

no special precautions; basic teaching labs

BSL-2

lab coat, gloves, eye protection

BSL-3

biosafety cabinets to prevent airborne transmission

BSL-4

sealed, negative pressure, exhaust air is filtered twice

Metabolism

All of the chemical reactions that occur within an organism

Anabolism

Metabolic pathways that construct molecules, requiring energy.

Catabolism (like a cat tearing stuff down)

Metabolic pathways that break down molecules, releasing energy.

Enzymes are what?

catalysts, that increase the rate of a chemical reaction by lowering the energy of activation

Enzymes serve as

physical site upon which the substrate of reactant can be positioned for various reactions.

Can enzymes be used up by the reaction?

no, enzymes can be used over and over

Simple enzymes

protein only

conjugated enzymes (holoenzymes)

contain protein and nonprotein molecules

Nonprotein molecules are called

cofactors

Cofactors are

either organic molecules which can be called coenzymes or inorganic elements such as metal ions

Coenzyme function is to

serve as a transient carrier of the functional group between substrate 1 and substrate 2

Microbial growth at a cellular level occurs with an increase in...

cell size, increase in cell population

What does division of bacterial cells mainly occur through?

binary fission

What happens in binary fission?

The cell replicates it's genetic material before physically splitting into two daughter cells

when a bacterial cell divides into two cells, each cell receives what?

complete chromosome, and an additional part of the genome