Oxidative phosphorylation Animation - Formation of ATP & sites of ATP synthesis

Summary

This script delves into oxidative phosphorylation, a vital cellular process for ATP production. It highlights three key ATP-synthesizing sites within the electron transport chain: between NAD and Coenzyme Q, Coenzyme Q and Cytochrome C, and Cytochrome C and Oxygen. The script explains the role of the F0F1 ATPase enzyme, commonly known as ATP synthase, in harnessing the proton gradient across the mitochondrial membrane to synthesize ATP. The mechanism of ATP synthesis is further elucidated through the binding change mechanism proposed by Paul Boyer, emphasizing the molecular motor function of the F1 complex and its gamma subunit's pivotal role in the process.

Takeaways

• 🌟 Oxidative phosphorylation is the process of ATP formation coupled with the transfer of electrons through the electron transport chain.
• 🔋 There are three main ATP synthesizing sites in the electron transport chain: between NADH and Coenzyme Q (Complex I), Coenzyme Q and Cytochrome C (Complex III), and Cytochrome C and Oxygen (Complex IV).
• ❌ Complex II does not contribute to ATP synthesis, highlighting the specificity of ATP production sites within the electron transport chain.
• 💡 The energy released at Complex I and Complex III is utilized to synthesize one ATP molecule at each site through the movement of hydrogen ions.
• 🔄 Complex IV (Site III) is unique as it only synthesizes half an ATP molecule due to the pumping of two hydrogen ions into the intermembrane space.
• 🔢 The entry of one NADH molecule into the respiratory chain results in the production of 2.5 ATP molecules, while one FADH2 molecule yields 1.5 ATP molecules.
• 🛠 The chemiosmotic theory by Peter Mitchell (1961) explains the coupling of oxidation and phosphorylation through a proton gradient across the mitochondrial membrane.
• 🔧 ATP synthase, also known as Complex V, is a molecular motor embedded in the inner mitochondrial membrane, consisting of F0 and F1 subcomplexes.
• 🔁 The F0 subcomplex forms a proton channel and is responsible for the rotation that drives ATP synthesis, while the F1 subcomplex contains the catalytic site for ATP production.
• 🔄 The gamma subunit of the F1 complex rotates due to the proton flow through F0, causing conformational changes necessary for ATP synthesis in the beta subunits.
• 🔒 Respiratory control refers to the tight coupling of electron flow and ATP synthesis, ensuring oxygen consumption is dependent on the availability of ADP.
• 🔄 The binding change mechanism, proposed by Paul Boyer, describes the process of ATP production involving the re-entry of protons and the subsequent rotation and conformational changes in the F1 complex.

Q & A

What is oxidative phosphorylation?

Oxidative phosphorylation is the process where ATP is formed during the transfer of electrons through the electron transport chain, coupled with the phosphorylation of ADP by an enzyme, utilizing the energy produced.

How many ATP synthesizing sites are there in the electron transport chain?

There are three ATP synthesizing sites in the electron transport chain: between NAD and Coenzyme Q (Complex I), between Coenzyme Q and Cytochrome C (Complex III), and between Cytochrome C and Oxygen (Complex IV).

Why does Complex II not produce any ATP?

Complex II does not pump protons into the intermembrane space, which is necessary for the generation of the electrochemical gradient that drives ATP synthesis.

How many ATP molecules are synthesized at Complex I and Complex III?

At both Complex I and Complex III, one ATP molecule is synthesized per site due to the proton gradient created by the pumping of four hydrogen ions.

What is the role of Complex IV in ATP synthesis?

Complex IV, also known as site three, is responsible for pumping two hydrogen ions into the intermembrane space, which results in the synthesis of only half an ATP molecule when they are pumped back into the mitochondrial matrix.

How many ATP molecules are produced when one NADH molecule enters the respiratory chain?

When one NADH molecule enters the respiratory chain, it produces 2.5 molecules of ATP, considering the energy liberation and proton gradient across the complexes.

What is the significance of the Kimmi osmotic theory in oxidative phosphorylation?

The Kimmi osmotic theory, proposed by Peter Mitchell, explains the coupling between the oxidation of reducing equivalents and the phosphorylation of ADP into ATP through a proton gradient across the mitochondrial membrane.

What are the two sub-complexes of ATP synthase?

The two sub-complexes of ATP synthase are Fo (also known as F naught), which is hydrophobic and forms a proton channel, and F1 (also known as F subunit), which is hydrophilic and contains the catalytic site for ATP synthesis.

How does the rotation of the Fo complex and the gamma subunit of F1 complex contribute to ATP synthesis?

The flow of protons through Fo causes the rotation of the Fo complex along with the gamma subunit of F1, which in turn causes conformational changes in the beta subunits of F1, leading to ATP synthesis.

What is the respiratory control, and how does it relate to ADP availability?

Respiratory control is the tight coupling of electron flow and ATP synthesis in mitochondria, ensuring that oxygen consumption depends on the availability of ADP. It adjusts electron flow and oxygen consumption based on the body's energy demands.

What is the binding change mechanism, and how does it explain ATP production in the F1 sub complex?

The binding change mechanism, proposed by Paul Boyer, states that the re-entry of protons through the Fo sub complex causes rotation of the gamma subunit of F1, leading to conformational changes in the beta subunits, which is the site of ATP synthesis.

Outlines

00:00

🔋 Oxidative Phosphorylation and ATP Synthesis Mechanism

The first paragraph delves into the biochemical process of oxidative phosphorylation, a critical component of cellular respiration. It explains how ATP is synthesized at three key sites within the electron transport chain: between NAD and Coenzyme Q (Complex I), Coenzyme Q and Cytochrome C (Complex III), and Cytochrome C and Oxygen (Complex IV). The paragraph clarifies that ATP is not produced at Complex II, and details the role of the enzyme F0F1 ATPase in the phosphorylation of ADP to ATP. It further discusses the energy released at these sites, emphasizing that the proton gradient created by the pumping of hydrogen ions is essential for ATP production. The paragraph also corrects previous assumptions about the ATP yield from NADH and FADH2, providing updated values of 2.5 and 1.5 ATP molecules respectively. Finally, it introduces the chemiosmotic theory proposed by Peter Mitchell, which explains the coupling of oxidation and phosphorylation through the proton gradient across the mitochondrial membrane.

05:02

🚀 Structure and Function of ATP Synthase Complex

The second paragraph focuses on the structure and function of the ATP synthase complex, also known as Complex V, which is embedded in the inner mitochondrial membrane. It describes the complex as having two sub-complexes: the hydrophobic F0 sub-complex, which forms a proton channel, and the hydrophilic F1 sub-complex, which is exposed to the mitochondrial matrix. The F0 sub-complex is composed of a disc of 10 c protein subunits, while the F1 sub-complex consists of nine subunits, including three alpha, three beta, and three additional subunits (gamma, delta, and epsilon). The gamma subunit is highlighted as a bent axle that, along with the F0 sub-complex, rotates due to the flow of protons, a movement that is essential for ATP synthesis. The beta subunit of the F1 complex is identified as the catalytic subunit where ATP synthesis occurs. The paragraph also explains the concept of respiratory control, which links electron flow and ATP synthesis to the availability of ADP, ensuring efficient oxygen consumption based on the body's energy demands.

10:05

🔄 Binding Change Mechanism in ATP Production

The third paragraph introduces the binding change mechanism, a theory proposed by Paul Boyer, which explains the ATP production process within the beta subunit of the F1 sub-complex. It describes how the re-entry of protons through the F0 sub-complex causes the rotation of the gamma subunit of the F1 sub-complex, leading to conformational changes in the beta subunits. These changes are crucial for the synthesis of ATP, highlighting the molecular motor aspect of the ATP synthase complex. The paragraph concludes the detailed discussion on oxidative phosphorylation, emphasizing the intricate and efficient process by which ATP is produced in the mitochondria.

Keywords

💡Oxidative Phosphorylation

Oxidative phosphorylation is the process by which cells produce ATP using the energy released from the transfer of electrons through the electron transport chain (ETC). It is central to the video's theme as it explains the synthesis of ATP during cellular respiration. The script mentions that this process is coupled with the oxidation of reducing equivalents, highlighting its role in energy production within the mitochondria.

💡ATP

ATP, or adenosine triphosphate, is the primary energy currency of the cell. The video script discusses the formation of ATP during oxidative phosphorylation, emphasizing its importance as the energy source for various cellular processes. The script explains that ATP is synthesized from ADP and inorganic phosphate, which is facilitated by the energy derived from the electron transport chain.

💡Electron Transport Chain (ETC)

The electron transport chain is a series of protein complexes that transfer electrons from electron donors to electron acceptors via redox reactions. In the context of the video, the ETC is crucial for the generation of energy that is used to produce ATP. The script identifies three ATP-synthesizing sites within the ETC, each associated with a different complex.

💡ADP

ADP, or adenosine diphosphate, is a molecule that becomes ATP upon gaining a phosphate group. The script discusses ADP in the context of ATP synthesis, where it is phosphorylated to form ATP during oxidative phosphorylation. ADP is a key concept in understanding the energy cycle of the cell.

💡Complex I, II, III, IV

These terms refer to the four main protein complexes involved in the electron transport chain. The script explains that Complex I and III pump protons into the intermembrane space, creating a proton gradient that drives ATP synthesis. Complex IV is responsible for the final step of electron transport and the pumping of the remaining protons. Complex II is mentioned as not being involved in ATP production.

💡Proton Gradient

A proton gradient is an electrochemical potential difference across a membrane, which in the context of the video, is created by the pumping of protons into the intermembrane space by the ETC. This gradient is essential for ATP synthesis, as it drives the rotation of the ATP synthase complex, leading to the phosphorylation of ADP to ATP.

💡ATP Synthase

ATP synthase, also known as Complex V, is a molecular motor enzyme that synthesizes ATP from ADP and inorganic phosphate. The script describes it as the smallest molecular motor in the human body and a key component in the process of oxidative phosphorylation. It is composed of two subcomplexes, F0 and F1, which work together to harness the energy from the proton gradient.

💡F0 and F1 Subcomplexes

F0 and F1 are subcomplexes of ATP synthase. The script explains that F0 is hydrophobic and embedded in the inner mitochondrial membrane, forming a proton channel, while F1 is hydrophilic and projects into the mitochondrial matrix. The interaction between these subcomplexes is critical for ATP synthesis, with the proton flow through F0 causing rotation that drives the F1 subcomplex.

💡Respiratory Control

Respiratory control refers to the regulation of electron flow and ATP synthesis in response to the availability of ADP. The script describes this phenomenon as a tight coupling mechanism that ensures oxygen consumption is dependent on the ADP levels. This concept is important for understanding how cells adjust their energy production based on demand.

💡Binding Change Mechanism

The binding change mechanism is a theory proposed by Paul Boyer that explains the catalytic action of ATP synthase. The script mentions this mechanism in the context of how proton re-entry through F0 causes the rotation of the gamma subunit of F1, leading to conformational changes that enable ATP synthesis. This mechanism is central to understanding the molecular process of ATP production.

Highlights

Oxidative phosphorylation is the process of ATP formation during the transfer of electrons through the electron transport chain.

Energy produced from electron transfer is coupled to ATP formation by the enzyme F1F0 ATP synthase.

There are three ATP synthesizing sites in the electron transport chain: between NAD and Coenzyme Q, Coenzyme Q and cytochrome C, and cytochrome C and oxygen.

Complex 2 does not produce ATP, unlike Complex 1, 3, and 4.

The energy liberated at Complex 1 is used to synthesize one ATP molecule, as does the energy at Complex 3.

Complex 4 is responsible for pumping two hydrogen ions, resulting in the synthesis of only half an ATP molecule.

One NADH molecule entering the respiratory chain produces 2.5 ATP molecules, while one FADH2 molecule produces 1.5 ATP molecules.

The values for ATP production per NADH and FADH2 have been updated from previous assumptions.

The chemiosmotic theory by Peter Mitchell (1961) explains the coupling of oxidation and phosphorylation through a proton gradient across the mitochondrial membrane.

ATP synthase, also known as Complex V, is the smallest molecular motor in the human body, embedded in the inner mitochondrial membrane.

ATP synthase consists of two subcomplexes: F0, which forms a proton channel, and F1, which is hydrophilic and projects into the mitochondrial matrix.

The gamma subunit of the F1 complex is a bent structure that rotates along with the F0 subcomplex, driven by the proton flow.

The rotation of the F0 and gamma subunit causes conformational changes in the beta subunit of F1, where ATP synthesis occurs.

Respiratory control is the tight coupling of electron flow and ATP synthesis, ensuring oxygen consumption depends on the availability of ADP.

The binding change mechanism by Paul Boyer explains the ATP production process in the beta subunit of the F1 complex through proton re-entry and gamma subunit rotation.

ATP synthase operates as a rotor-stator molecular motor with rotating and stationary subunits.

Transcripts

[Music]

oxidative phosphorylation in the

oxidative phosphorylation we are going

to talk about the formation of ATP and

the sites of

ATP synthesis during the transfer of

electrons through the electron transport

chain energy is produced and this energy

is coupled to the formation of ATP by

phosphorylation of ADP by an enzyme f o

f1 ATP ace and the phosphorylation of

adp into ATP is coupled with oxidation

of reducing equivalents therefore the

process is called as oxidative

phosphorylation so there are totally 3

ATP synthesizing sites of the electron

transport chain site one is between nad

and coenzyme q that is complex one site

two is between coenzyme Q and the

cytochrome C which is complex 3 and site

3 is between cytochrome C and oxygen

that is complex 4 so ATP synthesizing

complexes are in the electron transport

chain they are complex world complex 3

and complex 4 complex 2 is not producing

any ATP so these sites provide energy

required to make ATP from the ADP by an

enzyme f o f1 ATP is so not an important

point here that there is no ATP

formation at the complex 2 and the

energy which is liberated at the site 1

which is called as complex 1 is used to

synthesize one ATP molecule and at the

site 2 it is also used to synthesize one

ATP molecule because the 4 hydrogen ions

which are pumped into the intermembrane

space at the complex one and complex 3

and the same hydrogen protons are pumped

back into the

the control matrix by the concentration

gradient produces ATP molecules so

whenever four hydrogen ions which are

protons whenever they are pumped back

into the mitochondrial matrix due to

their electrochemical gradient produces

one ATP molecule that is the reason

complex one produces one ATP molecule

complex three also produces one ATP

molecule now let us talk about site

three which is called as complex four so

the complex four which is known as site

three of ATP synthesis is used to

synthesize only half ATP molecule

because the complex four is responsible

for only pumping of two hydrogen ions

into the intermembrane space when these

two hydrogen ions are kicked back into

the mitochondrial matrix because of the

proton gradient which has been created

because of the electrochemical gradient

only half molecule of ATP is produced so

that's why when one NADH molecule enters

the respiratory chain it produces 2.5

molecules of ATP and in the same way

when one molecule of fadh2 enters that

has been out any chain only 1.5

molecules of ATP are produced as site 1

of energy liberation is bypassed in this

so not an important point here

previously in the previous books also it

was assumed that one NADH produces 3 ATP

and one fadh2 produces 2 ATP's but the

values has been changed now now let us

discuss in detail about the mechanism of

oxidative phosphorylation there are so

many hypotheses but the most widely

accepted as well as the most acceptable

hypothesis which explains the mechanism

of association between the oxidation of

reducing equivalents and the

phosphorylation of ADP into ATP is the

Kimmi osmotic theory which is proposed

to by the Peter Mitchell in 1961 this

theory

explains that the two processes that is

oxidation and phosphorylation are

coupled by the proton gradient across

the mitochondrial membrane so this

proton motive force caused it by the

electrochemical potential difference

that is the negative on the matrix

because the hydrogen's are pumped into

the intermembrane space drives the

mechanism of ATP synthesis let us see

exactly what is happening here let us

see the structure of complex Y which is

also called as ATP synthase complex we

know that it is the smallest molecular

motor which is present in the human body

so it is also called as v complex of

electron transport chain even though it

is separately discussed as an oxidative

phosphorylation and I already mentioned

that it is the smallest molecular motor

present in the human body so location

that is the ATP synthase is embedded in

the inner mitochondrial membrane but as

you can see it has two components or two

sub complexes we can see if not sub

complex which is also called as FO

actually called as f0 so let us say it

is called as F naught F naught sub

complex and F 1 sub complex so what is

the F 1 sub complex F 1 sub complex is

hydrophilic in nature let's discuss

about F not sub complex the F not sub

complex is hydrophobic in nature and it

spans the inner mitochondrial membrane

which means it is fixed into the inner

mitochondrial membrane any component

which is fixed into the inner

mitochondrial membrane remember that it

is the lipid one right that is the

reason we are called as hydrophobic and

it forms a proton channel and it is made

up of a disc of 10 C protein subunits so

we can see very clearly that all the C

proteins which are arranged in a circle

which forms the F naught subunit and

what is the F 1 subunit F 1 subunit or

the F

sub complex is hydrophilic in nature

because it is not embedded in the inner

mitochondrial membrane but exposed into

the mitochondrial matrix that is the

reason it is the hydrophilic in nature

because it projects into the

mitochondrial matrix and this f1 is

attached to the F o sub complex and it

is made up of totally nine subunits

these are 3 alpha 3 beta one is gamma 1

is Delta and another one is epsilon so

it is made up of totally 9 subunits and

the gamma subunit if you examine very

clearly it is in the form of a bent axle

right it is not in a straight

orientation that is the reason it is

slightly a bending structure right it is

slightly bent there's a reason we will

call it as it is slightly looks like a

bent axle so the gamma subunit which is

slightly bent structure is surrounded by

3 alpha and 3 beta subunits right and

the flow of protons through F naught

causes the rotation of F naught complex

along with the gamma subunit of the f1

complex to rotate so we can see very

clearly here as the protons are pumped

back into the mitochondrial matrix

because of their electrochemical

gradient we can see the rotation of F

not because of the rotation of F not f1

the gamma subunit of the f1 is also

rotating along with the F naught so

which one is the statical the alpha beta

subunits which are not even rotating so

they are called as stationary subunits

so this rotation actually causes the

production of ATP in the f1 complex so

the beta subunit of the f1 complex is

called as catalytic subunit because it

is the place where ATP synthesis is

taking place

so this particular ATP synthase complex

as a rotor stator molecular motor

because it has two functional units

because one is the rotating subunit what

is the rotating subunit here F or

complex and gamma subunit of the f1

complex are rotating only these two are

rotating that is the reason these are

called as rotating subunits what is the

stationary subunit the f1 complex other

than gamma subunit because gamma is also

rotating which belongs to the f1 subunit

so f1 complex other than gamma subunit

is stationary it is not rotating at all

so that is the reason in ATP synthase we

have two subunits one is called as a

static right stationary another one is

called as rotate two subunits we have

here now let us talk about what is the

respiratory control there is a tight

coupling of electron flow and ATP

synthesis in the mitochondria ensures

that oxygen consumption depends upon

availability of ADP this phenomena is

called as respiratory control so what

does it explains which means whenever we

have low ADP low ADP means high ATP it

decreases flow of electrons which

decreases oxygen consumption during rest

in the same way if the concentration of

ADP in the mitochondrial matrix is high

which means ATP is low

it increases flow of electrons which

increases oxygen consumption which means

whenever we are exercising whenever our

body demands of oxygen increases

electron flow also increases now let us

talk about a new theory called as

binding change mechanism so here the

theory behind the ATP production in the

beta subunit of the f1 sub complex is

proposed mainly by Paul Boyer it states

that the re-entry of protons through the

F knot sub complex causes rotation of

the gamma subunit of

the f1 sub complex which in turn causes

conformational change in the beta

subunits of the f1 sub complex this is

called as binding change mechanism by

this we completed in detail about the

oxidative phosphorylation and in this we

also discussed about how the ATP

synthesis is taking place by means of a

complex molecular motor