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ATP synthase is an enzyme that spans the cytoplasmic membrane. H+ flow in through this protein from the outside of the cytoplasmic membrane into the cytoplasm. On the inner side of the protein, this flow of H+ is used to build ATP from ADP and Pi.
The bacterial electron transport chain is a series of protein complexes, electron carriers, and ion pumps that is used to pump H + out of the bacterial cytoplasm into the extracellular space. H + flows back down the electrochemical gradient into the bacterial cytoplasm through ATP synthase, providing the energy for ATP production by oxidative phosphorylation.(credit: modification of work by Klaus Hoffmeier)

The number of ATP molecules generated from the catabolism of glucose varies. For example, the number of hydrogen ions that the electron transport system complexes can pump through the membrane varies between different species of organisms. In aerobic respiration in mitochondria, the passage of electrons from one molecule of NADH generates enough proton motive force to make three ATP molecules by oxidative phosphorylation, whereas the passage of electrons from one molecule of FADH 2 generates enough proton motive force to make only two ATP molecules. Thus, the 10 NADH molecules made per glucose during glycolysis, the transition reaction, and the Krebs cycle carry enough energy to make 30 ATP molecules, whereas the two FADH 2 molecules made per glucose during these processes provide enough energy to make four ATP molecules. Overall, the theoretical maximum yield of ATP made during the complete aerobic respiration of glucose is 38 molecules, with four being made by substrate-level phosphorylation and 34 being made by oxidative phosphorylation ( [link] ). In reality, the total ATP yield is usually less, ranging from one to 34 ATP molecules, depending on whether the cell is using aerobic respiration or anaerobic respiration; in eukaryotic cells, some energy is expended to transport intermediates from the cytoplasm into the mitochondria, affecting ATP yield.

[link] summarizes the theoretical maximum yields of ATP from various processes during the complete aerobic respiration of one glucose molecule.

In glycolysis (EMP) carbon moves from glucose (6C) to 2 pyruvate (3C). The molecules of reduced coenzyme produced are 2 NADH. The net ATP molecules made by substrate level phosphorylation is 2 ATP. The net ATP molecules made by oxidative phosphorylation is 6 ATP from 2 NADH. The theoretical maximum yield of ATP molecules is 8. In the transition reaction carbon moves from 2 pyruvate (3C) to 2 acetyl (2C) + 2 CO2. The molecules of reduced coenzyme produced are 2 NADH. The net ATP molecules made by substrate level phosphorylation is 0 ATP. The net ATP molecules made by oxidative phosphorylation is 6 ATP from 2 NADH. The theoretical maximum yield of ATP molecules is 6. In the Krebs cycle carbon moves from 2 acetyl (2C) to 4 CO2. The molecules of reduced coenzyme produced are 6 NADH and 2 FADH2. The net ATP molecules made by substrate level phosphorylation is 2 ATP. The net ATP molecules made by oxidative phosphorylation is 18 ATP from 6 NADH and 4 ATP from 2 FADH2. The theoretical maximum yield of ATP molecules is 24. In total carbon moves from glucose (6C) to 6 CO2. The molecules of reduced coenzyme produced are 10 NADH and 2 FADH2. The net ATP molecules made by substrate level phosphorylation is 4 ATP. The net ATP molecules made by oxidative phosphorylation is 34 ATP. The theoretical maximum yield of ATP molecules is 38.
  • What are the functions of the proton motive force?

Key concepts and summary

  • Most ATP generated during the cellular respiration of glucose is made by oxidative phosphorylation .
  • An electron transport system (ETS) is composed of a series of membrane-associated protein complexes and associated mobile accessory electron carriers. The ETS is embedded in the cytoplasmic membrane of prokaryotes and the inner mitochondrial membrane of eukaryotes.
  • Each ETS complex has a different redox potential, and electrons move from electron carriers with more negative redox potential to those with more positive redox potential.
  • To carry out aerobic respiration , a cell requires oxygen as the final electron acceptor. A cell also needs a complete Krebs cycle, an appropriate cytochrome oxidase, and oxygen detoxification enzymes to prevent the harmful effects of oxygen radicals produced during aerobic respiration.
  • Organisms performing anaerobic respiration use alternative electron transport system carriers for the ultimate transfer of electrons to the final non-oxygen electron acceptors.
  • Microbes show great variation in the composition of their electron transport systems, which can be used for diagnostic purposes to help identify certain pathogens.
  • As electrons are passed from NADH and FADH 2 through an ETS, the electron loses energy. This energy is stored through the pumping of H + across the membrane, generating a proton motive force .
  • The energy of this proton motive force can be harnessed by allowing hydrogen ions to diffuse back through the membrane by chemiosmosis using ATP synthase . As hydrogen ions diffuse through down their electrochemical gradient, components of ATP synthase spin, making ATP from ADP and P i by oxidative phosphorylation.
  • Aerobic respiration forms more ATP (a maximum of 34 ATP molecules) during oxidative phosphorylation than does anaerobic respiration (between one and 32 ATP molecules).

Fill in the blank

The final ETS complex used in aerobic respiration that transfers energy-depleted electrons to oxygen to form H 2 O is called ________.

cytochrome oxidase

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The passage of hydrogen ions through ________ down their electrochemical gradient harnesses the energy needed for ATP synthesis by oxidative phosphorylation.

ATP synthase

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True/false

All organisms that use aerobic cellular respiration have cytochrome oxidase.

True

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Short answer

What is the relationship between chemiosmosis and the proton motive force?

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How does oxidative phosphorylation differ from substrate-level phosphorylation?

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How does the location of ATP synthase differ between prokaryotes and eukaryotes? Where do protons accumulate as a result of the ETS in each cell type?

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Questions & Answers

how does Neisseria cause meningitis
Nyibol Reply
what is microbiologist
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what is errata
Muhammad
is the branch of biology that deals with the study of microorganisms.
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What is microbiology
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studies of microbes
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How bacteria create energy to survive?
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Bacteria doesn't produce energy they are dependent upon their substrate in case of lack of nutrients they are able to make spores which helps them to sustain in harsh environments
_Adnan
But not all bacteria make spores, l mean Eukaryotic cells have Mitochondria which acts as powerhouse for them, since bacteria don't have it, what is the substitution for it?
Muhamad
they make spores
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the significance of food webs for disease transmission
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food webs brings about an infection as an individual depends on number of diseased foods or carriers dully.
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Esinniobiwa Reply
Assimilatory nitrate reduction is a process that occurs in some microorganisms, such as bacteria and archaea, in which nitrate (NO3-) is reduced to nitrite (NO2-), and then further reduced to ammonia (NH3).
Elkana
This process is called assimilatory nitrate reduction because the nitrogen that is produced is incorporated in the cells of microorganisms where it can be used in the synthesis of amino acids and other nitrogen products
Elkana
Examples of thermophilic organisms
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Give Examples of thermophilic organisms
Shu
advantages of normal Flora to the host
Micheal Reply
Prevent foreign microbes to the host
Abubakar
they provide healthier benefits to their hosts
ayesha
They are friends to host only when Host immune system is strong and become enemies when the host immune system is weakened . very bad relationship!
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what is cell
faisal Reply
cell is the smallest unit of life
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cell is the smallest unit of life
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ok
Innocent
cell is the structural and functional unit of life
Hasan
is the fundamental units of Life
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what are emergency diseases
Micheal Reply
There are nothing like emergency disease but there are some common medical emergency which can occur simultaneously like Bleeding,heart attack,Breathing difficulties,severe pain heart stock.Hope you will get my point .Have a nice day ❣️
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I think infection prevention and control is the avoidance of all things we do that gives out break of infections and promotion of health practices that promote life
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en français
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ESTHER Reply
Many sites of the body have it Skin Nasal cavity Oral cavity Gastro intestinal tract
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skin
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skin,Oral,Nasal,GIt
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all
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by fussion
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part of a tissue or an organ being wounded or bruised.
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what term is used to name and classify microorganisms?
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Binomial nomenclature
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Practice MCQ 5

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Source:  OpenStax, Microbiology. OpenStax CNX. Nov 01, 2016 Download for free at http://cnx.org/content/col12087/1.4
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