Microbial Diversity Exam 2 (copy) for plane

On the electron tower, where are the good electron donors?

At the top

On the electron tower, where are the good electron acceptors?

At the bottom

What does assimilative mean?

Process that requires energy

What does dissimilative mean?

Process that releases energy

What is autotrophy?

When CO2 is used as a carbon source

Even though it is the most studied, what is a downside to the Calvin Cycle?

Not extremely efficient

What is the reducing power for the Calvin Cycle?

NADPH

What type of molecule is Rubisco?

Enzyme

What are the two types of molecules that are trapped in a protein shell bacause of the carboxysome?

* Rubisco
* CO2

How do the reverse citric acid cycle and the hydroxypropionate pathways differ from one another?

* Efficiency
* Types of microbes

Where was photosynthesis originated?

Bacteria

What theory supports the idea that photosynthesis originated from bacteria?

Endosymbiotic Theory

What are the two types of reactions in photosynthesis?

* Light Independent Reactions
* Light Dependent Reactions

What does photosynthesis require?

* ATP
* Reducing power

What is the source of electrons is many diffferent reactions?

The reducing power

What is used as the reducing power for oxygenic photosynthesis?

H2O

What is used as the reducing power for anoxygenic photosynthesis?

Anything other than H2O

What are two examples of photosynthetic pigments?

* Chlorophylls
* Bacteriochlorophylls

Different photosynthetic pigments can absorb different wavelengths of light. What are two results of this?

* Microbes can live at different depths
* Allows for coexistance of microbes

What are reaction centers?

Molecules that briefly hold onto light

What are antenna pigments?

Pigments that capture and collect light

* Feeds light into the reaction centers

What is the benefit of the reaction center-antenna pigment system?

Allows for the ability to concentrate light

What are the light gathering machinery in Eukaryotes?

Chloroplasts

What are the light gathering machinery in Prokaryotes?

Membrane invaginations

Why are chlorosomes useful?

Great for capturing low density light

Do bacteria have chloroplasts?

No

Where can biomats live?

In the very center of the reaction center

What are carotenoids?

Pigments found in phototrophs that can absorb light

What is the main function of carotenoids?

Photoprotection

What are two benefits of photoprotection?

* Adaptation for high light environments
* Prevents destruction of reaction centers

What is created after the destruction of the reaction centers?

Oxygen singlets

What colors are carotenoids?

* Yellow
* Red
* Brown
* Green

What pigments are only found in Cyanobacteria?

Phycobilins

Why is anoxygenic photosynthesis different than normal photosynthesis?

Does not produce O2 as a product

What type of reaction is anoxygenic photosynthesis?

Endergonic

What is the source of electrons for anoxygenic photosynthesis?

Inorganic compounds

What are 2 unique characteristics of anoxygenic photosynthesis?

* Cyclic phosphorylation
* Reverse Electron Transport

What is the name of this process?

Reverse Electron Transport

How many photosystems are in oxygenic photosynthesis?

2

What does oxygenic photosynthesis use as a source of electrons?

H2O

What is the name of this process?

Oxygenic photosynthesis

What is unique about some organisms that can do oxygenic photosynthesis?

They also have the ability to do anoxygenic photosynthesis

What does cyclic flow of electrons generate in anoxygenic photosynthesis?

Proton Motive Force

Why do some microbes perform anoxygenic photosynthesis instead of oxygenic photosynthesis?

Some parts of microbe metabolism are oxygen sensitive

What are 4 processes that are defined by electron donor?

* Oxidation of Sulfur Compounds
* Iron oxidation
* Nitrification
* Anaerobic Ammonia Oxidation

What is often the end product of the oxidation of sulfur compounds?

Sulfate and H+

What can be a by-product of the large number of sulfur compounds?

Different amounts of electrons can be used

What is a potential side effect of the oxidation of sulfur compounds?

Acidification of the environment

What are two sulfur oxidizers?

* Acid tolerant microbes
* Acidophilic microbes

Why is oxidized sulfur held in the cell?

It is not fully oxidized and is a future source of energy

Microbes that can do autotrophy can also oxidize sulfur compounds. What process would result from this?

Reverse electron transport because sulfur comes in low on the electron tower

In the traditional sulfur oxidation pathway, what is generated?

Many H+ and sulfate (by-product)

What is oxidized in iron oxidation?

Fe2+ to Fe3+

What are 2 side effects of iron oxidation?

* Environment acidification
* Color changes

What happens to the iron oxidation process in an acidic environment?

* Large amounts of iron must be oxidized
* Iron oxidation causes little energy to be present in an acidic environment

What happens to the iron oxidation process in a neutral environment?

* O2 is present and oxidation is spontaneous
* Microbes now have to compete with natural iron processes

Under the acidic conditions, what happens with the ETC in iron oxidation?

* Not many electron carriers between iron and O2
* Produces a short ETC and little energy

Under acidic conditions, what happens with the PMF in iron oxidation?

* Acidic environment creates a preformed proton gradient
* The cell cannot utilize the preformed PMF due to pH homeostasis
* Protons still have to be pumped out of the cell to create the PMF

What organisms are going to use nitrification for their electrons?

Chemolithotrophs

What is the first of two reactions for nitrification?

Oxidation of ammonia nitrite

What is the second reaction for nitrification?

Oxidation of nitrite to nitrate

What types of microbes oxidize ammonia to nitrite?

Ammonia oxidizers

What types of microbes oxidize nitrite to nitrate?

Nitrite oxidizers

Can any microbes do both of the nitrification processes?

Yes, the genus *Nitrospira*

What is the terminal electron acceptor for nitrification?

O2

What is the reducing power for autotrophs in nitrification?

Reverse electron flow

What is another name for anaerobic ammonia oxidation?

Anammox

When is anammox performed?

NH3 is oxidized under anoxic conditions

What are anammoxosomes?

* Membrane bound
* Produce N2H4
* Intermediate for anammox

What is the purpose of anammoxosomes?

Prevent the toxic N2H4 form being released into the cell

What organisms are capable of anammox?

*Planctomycetes*

3 processes that are defined by their electron acceptor?

* Nitrate reduction and denitrification
* Sulfate reduction
* Other electron acceptors

What is nitrate reduction?

Inorganic nitrogen compounds are commonly used as electron acceptors

What type of process of denitrification?

Dissimilative

What are 3 possible results of denitrification?

* NO
* N2O
* N2

What is the process of denitrification?

NO3- → N2

What is the proccess of nitrate reduction?

NO3- → NO2-

What are the negative impacts of leaving nitrogen compounds in NO or N2O?

* Increase greenhouse gases
* Formation of acid rain
* Removal of nitrogen from the environment

How do dead zones and algae blooms form?

Too much nitrogen

Why are waterlogged fields bad for microbes that use nitrogen reduction and denitrification?

Nitrogen reductase enzyme is oxygen sensitive and oxygen will stop the entire process

What types of microbes use sulfate reduction?

Obligate anaerobes

What is the end product of sulfate reduction regardless of the reactants?

H2S

When looking at the electron tower, what is the problem with sulfate reduction?

Sulfate is a good donor, but needs to be used as a terminal electron acceptor for sulfate reduction

What type of process is sulfate reduction?

Endergonic

What is one other example of an electron acceptor?

Arsenic

Is hydrocarbon metabolism an aerobic process or an anaerobic process?

It can be both

What are the two enzymes that can be utilized during aerobic hydrocarbon metabolism?

* Monoxygenase
* Dioxygenase

What must the cell do in hydrocarbon metabolism?

Energize the carbons

What happens once the carbons are energized in hydrocarbon metabolism?

Oxygen is added

What is added in place of oxygen in anaerobic hydrocarbon metabolism?

Fumarate

What are 3 processes that are one-carbon metabolism processes?

* Acetogenesis
* Methanogenesis
* Methanotrophy

What do both accetogenesis and methanogenesis have in common?

* Reduce CO2 (in the form of bicarbonate)
* Strict anaerobes

What type of gradient is generated in methanogenesis and/or acetogenesis to form ATP?

Ion or proton motive force

What is the electron donor is acetogenesis?

H2

What is the pathway of CO2 reduction called?

Reductive acetyl CoA pathway

What are the two different types of organisms that can do acetogenesis?

* Chemoorganotrophs (heterotrophs)
* Chemolithotrophs (autotrophs)

What makes the Acetyl-CoA pathway unique?

It is linear

What generates the bulk of the ATP in acetogenesis?

Na+ motive force

What is the cluster of proteins called where ferredoxin goes through the redox reaction?

RNF cluster of proteins

If energy is released from the redox of ferredoxin, what does this energy contribute to?

The generation of the ion motive force