Anaerobic Respiration Process

Which of the following can facultative anaerobes such as enteric bacteria use as a terminal electron acceptor in the absence of oxygen?

What do bacteria that reduce carbon dioxide to methane called?

Which of the following is a reason why anaerobic respiration is less efficient than aerobic respiration?

What will happen to glycolysis if NAD+ and FAD+ are not replenished?

What happens in bacterial respiration when a non-O2 acceptor is used?

What is the primary product when pyruvate is degraded aerobically?

Which cycle provides carbon skeletons for biosynthesis?

Which bacteria do not use the full TCA cycle under anaerobic conditions?

How many ATP molecules are generated from the complete oxidation of one glucose molecule through glycolysis, TCA cycle, and electron transport?

Which process occurs in the absence of aerobic or anaerobic respiration?

What are the products of the TCA cycle?

Which pathway is most commonly used for the breakdown of glucose to pyruvate?

Where does the glycolytic pathway take place in bacteria?

Which pathway can operate both aerobically and anaerobically and is also important in biosynthesis?

Which of the following bacteria does NOT typically use the Entner-Doudoroff pathway?

What is the end product common to the glycolytic pathway, pentose phosphate pathway, and Entner-Doudoroff pathway?

Anaerobic Respiration

Bacteria can use electron transport chains with exogenous electron acceptors other than oxygen, such as nitrate, sulphate, or carbon dioxide, which is less efficient in producing ATP due to less positive reduction potentials.
Facultative anaerobes, like enteric bacteria, can use nitrate as a terminal acceptor in the absence of oxygen, while obligate anaerobes cannot use oxygen at all.
Methanogens, which use carbon dioxide or carbonate as electron acceptors, reduce carbon dioxide to methane.

Bacterial Respiration

Using non-oxygen acceptors results in less H+ and less ATP generated.

Replenishment of NAD+ / FAD+

Replenishment of NAD+ and FAD+ is necessary to prevent glycolysis from stopping.

Glucose to Pyruvate

The second stage of metabolism involves the breakdown of glucose to pyruvate or acetyl-CoA through glycolytic pathways, including the Embden-Meyerhof-Parnas (EMP) pathway, pentose phosphate pathway, and Entner-Doudoroff pathway.
The EMP pathway is the most common and takes place in the cytoplasm of bacteria.

Entner-Doudoroff Pathway

The Entner-Doudoroff pathway is used in a few bacteria, such as Pseudomonas spp. and some Gram-positive bacteria, and can operate aerobically or anaerobically.
It can occur simultaneously with the glycolytic and pentose phosphate pathways and is important in biosynthesis.

Maximising Energetic Return

The third stage of metabolism involves aerobic, anaerobic respiration, and fermentation.
Pyruvate can be oxidized to carbon dioxide and acetyl-CoA, which can enter the TCA cycle.

Aerobic Respiration

Aerobic respiration releases the most energy in the form of ATP when pyruvate is degraded to carbon dioxide.
Acetyl-CoA enters the TCA cycle, which is functional in many aerobic bacteria, free-living protozoa, and most algae and fungi.
The TCA cycle provides carbon skeletons for biosynthesis.

TCA Cycle (Krebs / Citric Acid Cycle)

The TCA cycle produces carbon dioxide, ATP, NADH, and FADH.
Most ATP is generated when NADH and FADH are oxidized in the electron transport chain.
The TCA cycle and electron transport result in a net energy gain of 38 ATP per glucose molecule.

This quiz covers anaerobic respiration, including bacterial respiration with alternative electron acceptors, less efficient ATP production, and its characteristics.