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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

what is prokaryotes
PRALHAD Reply
are micro-organisms that have no nucleus e.g bacteria
Foster
and they do not possess membrane bound organelles e.g mitochondria
Bharat
yes
Foster
they are single cellular organisms,
Rajasekhar
all the organelles are embedded in cytoplasm of the cell
Rajasekhar
They don't possess true nucleus
PREMI
they're unicellular organisms
Kamaluddeen
they are classified as bacteria and. archaea. bacteria have a cell membrane conposed of peptidoglycan and archaea is composed of psuedomu
Tara
pseudomurein
Tara
organelles are non membraneous as the nucleus
Tara
What is the biosynthesis of a bacteria cell
Adesina Reply
biosynthesis is multiple step enzymes catalyze process which occur in bacterial cell
Jayeeta
biological way of manufacturing food and utilizes it for growth, multiplication and development
Kamaluddeen
prokaryot
PRALHAD
what is microbiology
Kiirya Reply
which organism can not be seen necked eyes is knowm as microbiology
meet
microorganisms
Jayeeta
micro can be define as d smallest living organisms dat can not be see wit naked eyes only with the aid of a microscope 🔬
muhammed
bio means life logy means study
muhammed
biology can b define as the systematic study of living things
muhammed
microbiology can be define as the study of tiny organisms, that's according to my understanding
muhammed
Microbiology is the study of living organisms which cannot be seen by the naked eye but only with the aid of a microscope. These microorganisms can be classified as bacteria, fungi, micro-algae, protozoa and virus.
Tatz
microbes that can't seen in naked eyes. upto 100micrometer we can see in naked eyes but 1 microns or nanometers are invisible in naked eye.
Jayeeta
what is a cell
Oteri Reply
cell can be define as smallest indivisible organism in the body
muhammed
cell is the smallest unit which makes up the whole body
Yue
cell is smallest unit and there are two types prokaryotic cell and eukaryote cell. bacteria a prokaryotic cell which works independently.
Jayeeta
nice forum
muhammed
Which parasite competes with the host for vitamin B12 to cause pernicious anaemia
Abubakar
Diphyllobothrium latum for vit B12
Jayeeta
it is also fish tapeworm
Jayeeta
Diphyllobothrium sp feed vitB 12
Jayeeta
recent trends in microbiology of biofertilizer
Ykomalipriya Reply
using nano technology
Jayeeta
what is transposors
EMMANUEL Reply
Junk DNA, jumping gene.
Pradeep
transposon elements are jumping gene as DNA sequence move from one location to anothet
Jayeeta
Yes
Pradeep
what is microbiology
Usama Reply
Microbiology is the study of organisms, most of which are too small to be seen with the naked eye, including bacteria, algae, protozoa, and fungi, as well as acellular agents, such as viruses and prions.
digvijaya
what is gram +ve and gram - ve bacteria?
Sharma
gm- contain lipid layer so it take counter stain during gram staining and pink or red in color but gm + does have thick LPS layer.
Jayeeta
what year microbiology started
Kartik
Robert Koch was the first to detect microorganisms
Jayeeta
what appears microorganisms
Kartik
clear the questions please
Jayeeta
was it robert koch or robert hooke?
digvijaya
microbiology word came from microns. study microbes that not recognize in naked eyes.
Jayeeta
what are the branch of microbiology
Oyemade Reply
We can basically classify into pure and applied microbiology
Ozzie
what is arabinose operon and it's stucture
Pooja Reply
The L-arabinose operon, also called the ara or araBAD operon, is an operon required for the breakdown of the five-carbon sugar, L-arabinose, in Escherichia coli
Tharra
kya hum operon ko divide kar skate hain
Kartik
reactions if viruses to physical and chemical agents?
VICTOR Reply
All viruses contain the following two components: 1) a nucleic acid genome and 2) a protein capsid that covers the genome. Together this is called the nucleocapsid. In addition, many animal viruses contain a 3) lipid envelope. The entire intact virus is called the virion.
Asali
assume you have performed a gram stain on a sample of pus from a patients urethra. you see red, nucleated cells and purple rods. what can you conclude
Petty Reply
bacteria
ABUBAKAR
gram negative bacteria hence gonococcal infection
Kiirya
Study of micro organisation which we cannot see with naked eye...
shyam Reply
Despite their bad reputation, microbes are mostly beneficial or have a neutral effect on our lives. Microbiology is the scientific study of these microorganisms. Microorganisms are those organisms that are too small to see with the naked eye and include things like bacteria, fungi, and viruses.
Asali
yes
Dhirender
not 'things'...'organisms' like bacterias, viruses and fungi
Sinmi
simi, it's not bacterias but bacteria which is the plural form of the word while bacterium is the singular of it
Richard
bacterium is obvio in a singular form but plural of bacterium is bacterias
Sinmi
Richard is right it's bacterium which is the singular form and plural is bacteria. *Bacterias* doesn't exist.
Aakriti
that is microbiology which is deals with microbes only their structure
Kiirya
what is microbiology?
Sandeep Reply
what is microbiology
Glory
is the study of small microorganisms that can't be viewed by our naked eyes under a microscope
Nabukwasi
it's the study of microbes their classification, diversity, their cellular structure and processes, their applications and interaction with other organisms.
Chaitanya
what is EMP pathway
rajesh
which organism is implicated in meningoencephalitis
Peter Reply
Herpes virus
Carlos
Yeah
Laxmi
which mold is called dairy mold?
Gopinath
mushroomm
Top
Geotrichum candidum
Gopinath
hi
bio
Hlw
Laxmi
which infectious agent is the smallest
Sinmi
spore or virus
Anushree
prion ....it is a single protein in a misfolded form..there is also a theory based on it
Sinmi
yup...m sry
Anushree
yes it can be turned as a virus
Sinmi
which gram positive bacteria is responsible for food poisoning?
Sinmi
prion is not a living organism yet it is infectoois why
Jeevan
prions are virus like organism. and it is a misfolded protein that may cause disease to us.
Tharra
Clostridium perfringens, B.cereus
Sneha
Who is the father of the biology
Dhirender
I have one more question. . that who is the father of botany and medicine? ? can any one tell
Dhirender
define polar bond in simple way
Rashmi Reply
when there is formation of positive and negative poles i.e. one atom is +ve and other is -ve which further results in the dipole moment. Such bond is know as polar bond. It is a convalent bond only.
Aakriti
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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