Photosynthesis and Bacterial Energetics Quiz

A type of bacteria that can use tetrathionate as a terminal electron acceptor. This allows Salmonella to outcompete other bacteria in the gut during an inflammatory response.

A process where a bacterium uses waste products, like tetrathionate, as a final electron acceptor in its respiratory chain. This allows the bacterium to generate energy.

A type of bacteria that produces lactic acid as a byproduct of fermentation. They generate ATP through substrate-level phosphorylation during glycolysis.

The enzyme complex that generates ATP through oxidative phosphorylation. Its function is reversible, meaning it can either pump protons across the membrane or generate ATP, depending on the conditions.

The movement of electrons along a chain of proteins, coupled with the pumping of protons across a membrane. This process generates a proton motive force that drives ATP synthesis.

A process where electrons are transferred from a donor molecule, like glucose, to a final acceptor molecule, like oxygen. This process releases energy used for ATP synthesis.

The breakdown of glucose into pyruvate and then into acetyl-CoA, followed by the citric acid cycle. This process produces electrons carried by NADH and FADH2, which are then used in the electron transport chain for ATP synthesis.

The process by which plants capture light energy and convert it into chemical energy in the form of glucose. It is the foundation of life on Earth.

A type of protein that uses light energy to pump protons across a membrane, creating a proton gradient that drives ATP synthesis.

Photosynthesis is the process by which organisms convert light energy into chemical energy in the form of ATP and NAD(P)H. The process is essentially a light-driven redox reaction and the light energy can be used to move electrons from a low-energy to a high-energy state to create a gradient that produces ATP.

Chlorophyll a is a pigment that absorbs light energy, primarily in the red and blue wavelengths, and uses it to power the light-dependent reactions of photosynthesis.

Bacteriochlorophyll a is similar to chlorophyll a, but absorbs light in the infrared region of the spectrum. It is found in some photosynthetic bacteria.

Accessory pigments help expand the range of light wavelengths a photosynthetic organism can use. Carotenoids are an important example, absorbing light energy from the green wavelengths that chlorophyll a does not absorb well.

Carotenoids are a group of pigments that are important for light harvesting in photosynthesis. They absorb light in the blue and green wavelengths, giving plants their orange and yellow hues.

The degradation of chlorophyll in autumn leaves reveals other pigments, such as carotenoids and anthocyanins, creating the vibrant fall colors.

Photosynthetic organisms utilize electron donors that are not chemically favorable on their own.  The light energy is harnessed to move electrons to higher energy states and create a favorable condition for energy production. 

Photosynthesis which uses water as the source of electrons and produces oxygen as a byproduct.

Photosynthesis which uses other molecules like hydrogen sulfide as the source of electrons and does not produce oxygen.

A type of photosynthetic bacteria that uses water as the electron donor and releases oxygen as a byproduct.

A group of photosynthetic bacteria that use various electron donors and DO NOT produce oxygen.

Purple bacteria that use reduced sulfur compounds (like hydrogen sulfide) as electron donors.

Purple bacteria that use organic molecules (like carbohydrates) as electron donors.

The process by which purple bacteria generate ATP after light absorption. It involves electrons flowing backwards through the electron transport chain.

The Calvin cycle is a series of metabolic reactions that fix CO2 to produce glucose. It's used by plants, cyanobacteria, and purple bacteria.

An example of a protonophore (uncoupler) that disrupts the proton gradient across the membrane, inhibiting ATP production.

A complex protein that captures light energy and drives the initial electron flow in photosynthesis.

The Great Oxidation Event was a period in Earth's history when the atmosphere became oxygen-rich, primarily due to the emergence of oxygenic photosynthesis by cyanobacteria.

Phycobilins are accessory pigments found in cyanobacteria that absorb light energy and transfer it to chlorophyll.

Prochlorococcus is a type of cyanobacteria abundant in oceans, particularly in the mid-latitudes.

Microbial mats are layered communities of microorganisms, often including cyanobacteria, diatoms, and sulfur bacteria.

Diatoms are a type of algae that use chlorophyll a for photosynthesis and are often found in microbial mats.

Green sulfur bacteria are photosynthetic bacteria that use sulfur compounds for energy and have unique chlorosomes for light harvesting.

Green sulfur bacteria (GSB) are anaerobic photosynthetic bacteria that use hydrogen sulfide (H2S) or other inorganic electron donors like thiosulfate or Fe2+ to generate energy. They deposit sulfur (S0) extracellularly.

GSB have specialized light-harvesting structures called chlorosomes that allow them to grow in low-light environments, like deep waters or sediments.

GSB use a modified version of the tricarboxylic acid (TCA) cycle, called the reverse TCA cycle, to fix carbon dioxide (CO2). This is different from the Calvin cycle used by plants and cyanobacteria.

GSB reaction centers resemble photosystem I (PSI) in cyanobacteria and chloroplasts, suggesting a common evolutionary origin.

The electron donor crisis refers to the challenge faced by early photosynthetic organisms as they ran out of readily available electron donors like H2S. This led to the evolution of oxygenic photosynthesis.

Oxygenic photosynthesis uses water (H2O) as an electron donor, which is plentiful but difficult to oxidize. This process releases oxygen as a byproduct.

In oxygenic photosynthesis, electrons flow through two photosystems (PSI and PSII) and produce ATP and NADPH. This allows for the fixation of CO2 via the Calvin cycle.

The development of oxygenic photosynthesis was a major evolutionary leap, as it allowed organisms to utilize the abundant water as an electron donor, leading to the rise of oxygen in Earth's atmosphere.