Section 24.3 (Exam 1) Flashcards
Ecological Communities Depend on Prokaryotes
___________ usually live in communities of many different microbial species.
Prokaryotes
What are biofilms?
A gel-like polysaccharide matrix that traps other cells; forms when cells contact a solid surface.
Human health depends in part on the health of the communities of what that live in our body? What is this called?
Communities of bacteria. Microbiome.
Babies born by C-section or bottle-fed artificial formula have higher incidences of what? Why?
Auto-immune disease. Because they never acquired the proper bacteria, and don’t have a healthy microbiome.
How do you get vitamins B12 and K?
They are absorbed by your gut microbiome.
The biofilm that lines human intestines functions like a specialized “tissue” in what way?
By facilitating nutrient uptake.
Name Koch’s Postulates to establish that a specific organism causes a specific disease.
Microorganism is found in afflicted individual.
Microorganism is isolated and grown in PURE culture.
A sample of the pure culture can infect a healthy individual successfully.
The victim yields a PURE culture.
For an organism to become a pathogen it must:
Arrive at the body surface of a host.
Enter the host’s body.
Evade the host’s defenses.
Multiply inside the host.
Infect a new host.
What is a pathogen’s invasiveness?
Its ability to multiply.
What is a pathogen’s toxigenicity?
Its ability to produce toxins.
Diptheria bacteria has low or high toxigenicity and low or high invasiveness?
high toxigenicity; low invasiveness
Bacillus anthracis (anthrax bacteria) has low or high toxigenicity and low or high invasiveness?
low toxigenicity; high invasiveness
Endotoxins are released when Gram-___________ bacteria are lysed.
Gram-negative
Endotoxins are ___________________________ from the outer membrane.
lipopolysaccharides
Are endotoxins fatal?
Rarely.
Exotoxins are soluble __________ released by living bacteria.
proteins
List 5 examples of exotoxin induced diseases.
Tetanus (Clostridium tetani)
Botulism (Clostridium botulinum)
Cholera (Vibrio cholerae)
Plague (Yersinia pestis)
Anthrax (Bacillus anthracis)
Prokaryotes have more or less metabolic pathways than eukaryotes?
more
Name some (10) prokaryote metabolic pathways?
Anaerobic
Aerobic
Photoautotrophs
Photoheterotrophs
Chemoautotrophs
Chemoheterotrophs
Decomposers
Denitrifiers
Nitrogen-fixers
Nitrifiers
What are facultative anaerobes?
Can shift metabolism between aerobic and anaerobic modes, such as fermentation.
What are aerotolerant anaerobes?
They are not damaged by oxygen, but do not conduct cellular respiration.
What are obligate aerobes?
They cannot survive without oxygen.
Photoautotrophs perform _____________, meaning they obtain carbon from _____________.
photosynthesis; Carbon dioxide (CO2)
Bacteriochlorophyll is used as a photosynthetic pigment by some members of which prokaryote group defined by their metabolic pathway?
Photoautotrophs
Bacteriochlorophyll absorbs _________ wavelengths of light than chlorophyll. This means they can live in water under dense layers of algae.
longer
Bacteriochlorophyll use something in place of H2O as an electron donor. What is it?
Hydrogen Sulfide (H2S)
Photoheterotrophs use light for ___________ and obtain carbon from ______________.
energy; organic compounds
____________________ get energy by oxidizing inorganic compounds and get carbon by using that energy to fix CO2.
Chemoautotrophs
Chemoheterotrophs obtain both energy and carbon from __________________________________________.
complex organic compounds that were synthesized by other organisms.
A few species of chemoheterotrophs get energy from the breakdown of inorganic molecules. What are they called?
Lithotrophs
_______________ metabolize organic compounds in dead organisms and other organic materials.
Decomposers
______________ convert N2 gas into ammonia (NH3).
Which organisms perform this action?
Nitrogen-fixers
Nitrogen fixing is done by archaea and bacteria like cyanobacteria, but NOT done by eukaryotes.
___________ are chemoautotrophic bacteria. They oxidize ammonia (NH3) into nitrite (NO2-) and then oxidize nitrite (NO2-) into nitrate (NO3-).
Nitrifiers
What are some common nitrifiers that oxidize ammonia? Which ones oxidize nitrite?
Nitrosomonas and Nitrosococcus oxidize ammonia. Nitrobacter oxidizes nitrite.
____________ use nitrate (NO3-) as an electron acceptor in anaerobic conditions. They use the oxygen for themselves and release nitrogen gas (N2) to the atmosphere. Almost all of them could be considered _________________________.
Denitrifiers; facultative anaerobes
What are some examples of denitrifiers?
Bacillus and Pseudomonas
Why is it hard to classify viruses?
Tiny genomes, mutate fast, no fossils, very diverse
How do we classify viruses?
Genome structure
