Electron Transport Chain ETC Made Easy

preview_player
Показать описание
GET LECTURE HANDOUTS and other DOWNLOADABLE CONTENT FROM THIS VIDEO
SUPPORT US ON PATREON OR JOIN HERE ON YOUTUBE.

Electron Transport Chain ETC Made Easy

An electron transport chain (ETC) is a series of complexes that transfer electrons from electron donors to electron acceptors via redox (both reduction and oxidation occurring simultaneously) reactions, and couples this electron transfer with the transfer of protons (H+ ions) across a membrane. This creates an electrochemical proton gradient that drives the synthesis of adenosine triphosphate (ATP), a molecule that stores energy chemically in the form of highly strained bonds. The molecules of the chain include peptides, enzymes (which are proteins or protein complexes), and others. The final acceptor of electrons in the electron transport chain during aerobic respiration is molecular oxygen although a variety of acceptors other than oxygen such as sulfate exist in anaerobic respiration.

In chloroplasts, light drives the conversion of water to oxygen and NADP+ to NADPH with transfer of H+ ions across chloroplast membranes. In mitochondria, it is the conversion of oxygen to water, NADH to NAD+ and succinate to fumarate that are required to generate the proton gradient.
Complex I
In Complex I (NADH:ubiquinone oxidoreductase, NADH-CoQ reductase, or NADH dehydrogenase; EC 1.6.5.3), two electrons are removed from NADH and ultimately transferred to a lipid-soluble carrier, ubiquinone (Q). The reduced product, ubiquinol (QH2), freely diffuses within the membrane, and Complex I translocates four protons (H+) across the membrane, thus producing a proton gradient. Complex I is one of the main sites at which premature electron leakage to oxygen occurs, thus being one of the main sites of production of superoxide.
The pathway of electrons is as follows:

NADH is oxidized to NAD+, by reducing Flavin mononucleotide to FMNH2 in one two-electron step. FMNH2 is then oxidized in two one-electron steps, through a semiquinone intermediate. Each electron thus transfers from the FMNH2 to an Fe-S cluster, from the Fe-S cluster to ubiquinone (Q). Transfer of the first electron results in the free-radical (semiquinone) form of Q, and transfer of the second electron reduces the semiquinone form to the ubiquinol form, QH2. During this process, four protons are translocated from the mitochondrial matrix to the intermembrane space. [4] As the electrons become continuously oxidized and reduced throughout the complex an electron current is produced along the 180 Angstrom width of the complex within the membrane. This current powers the active transport of four protons to the intermembrane space per two electrons from NADH.
Complex II
In Complex II (succinate dehydrogenase or succinate-CoQ reductase; EC 1.3.5.1) additional electrons are delivered into the quinone pool (Q) originating from succinate and transferred (via flavin adenine dinucleotide (FAD)) to Q. Complex II consists of four protein subunits: succinate dehydrogenase, (SDHA); succinate dehydrogenase [ubiquinone] iron-sulfur subunit, mitochondrial, (SDHB); succinate dehydrogenase complex subunit C, (SDHC) and succinate dehydrogenase complex, subunit D, (SDHD). Other electron donors (e.g., fatty acids and glycerol 3-phosphate) also direct electrons into Q (via FAD). Complex 2 is a parallel electron transport pathway to complex 1, but unlike complex 1, no protons are transported to the intermembrane space in this pathway. Therefore, the pathway through complex 2 contributes less energy to the overall electron transport chain process.

Complex III
In Complex III (cytochrome bc1 complex or CoQH2-cytochrome c reductase; EC 1.10.2.2), the Q-cycle contributes to the proton gradient by an asymmetric absorption/release of protons. Two electrons are removed from QH2 at the QO site and sequentially transferred to two molecules of cytochrome c, a water-soluble electron carrier located within the intermembrane space. The two other electrons sequentially pass across the protein to the Qi site where the quinone part of ubiquinone is reduced to quinol. A proton gradient is formed by one quinol (2H+2e-) oxidations at the Qo site to form one quinone (2H+2e-) at the Qi site. (in total four protons are translocated: two protons reduce quinone to quinol and two protons are released from two ubiquinol molecules).

QH2 + 2 cytochrome c (FeIII) + 2 H+in → Q + 2 cytochrome c (FeII) + 4 H+out
When electron transfer is reduced (by a high membrane potential or respiratory inhibitors such as antimycin A), Complex III may leak electrons to molecular oxygen, resulting in superoxide formation.

-~-~~-~~~-~~-~-
CHECK OUT NEWEST VIDEO: "Nucleic acids - DNA and RNA structure "
-~-~~-~~~-~~-~-
Рекомендации по теме
Комментарии
Автор

Best video for ETS available on YouTube.You explain so nicely.I really loved the video and know I know it's basics. So thanks for it.

sukumaljain
Автор

Best tutorial video have ever seen honestly, i have exam in few hours and i have been reading and watching videos across the net to no avail, luckily i come across your video.You such a blessing.made simple, clear and concise.God bless you.

michaelhabeeb
Автор

salute to Dr, Rishabh sir who made it even more easier
like a peice of cake

themusicuniverse
Автор

Best video I have ever seen breaking down the ETC. I have studied biological processes for 3 years, taken biochemistry, and this video chunks the topics so perfectly. Amazing.

xnzsitk
Автор

You have taught this complicated topic in such a simple manner God bless you sir you are one of the best online teacher I have ever found💯

editvideos
Автор

oh ! So...Best. To the point and No shit. Loved the handwriting pattern, The colours used..And the timing and speed of video too. Lovely :)

dulcetkomal
Автор

My teacher took 3 hours to teach this and I learned it less than 20 mins. Thank you

jeffreybelvedere
Автор

wow I am so glad to find your videos!! they are simple yet covers all that i need to know. It has saved me so much time from having to ready all the wordy/confusing textbook contents!! thank you!

xoxolavender
Автор

THANK YOU SO MUCH U SAVE MY LIFE. Nobody ever explained to me so beautifully like this

manaalnizar
Автор

Great video! Appreciate how your explanation is clear and to the point. thank you!

HuePham-rsxv
Автор

This guy truly holds the power to simplify the complexes of Medical Studies....

valentinerkmusic
Автор

i opened ncert, my brain cells died. now they've revived. there's this one BIG bob of a 'paragraph' and i was like nah. THIS, is wonders.

varshitakolipaka
Автор

Thank you I understood the the most difficult cycle in respiration in plants through this video

mounikanutakki
Автор

I watched many vdeos but this was the perfect & simple.... Thank u sir...

sabihamahveen
Автор

I have tests coming up soon😅 I've been given the task to explain biochemistry to my friends in study group. Iam watching your videos and explaining them 😅 you saved alot of time bro. A big hearty thanks🙏.

Nova-uszo
Автор

i dont know how else i can thank you guys enough, i was handed ETC as a single reporter and i panicked, but this video? where do i even start, you guys should REPLACE MY BIOCHEM TEACHER, the illustration was perfect, the diction and explanation was so clear ( it was so clear that even a dumb ass like me who always falls asleep in biochem class god it, yes its that good!) and everything else was just perfect. This video is dumb-ass proof and is so useful! thank you again!

stefanosdelacruz
Автор

this is THE BESTTT THING EVERRR!!! my exam is tomorrow morning and honestly never would i have understood it this well and this quickly without this video. THANK YOU THANK YOU THANK SENDING MANY WISHES AND PRAYERSSS

laibazahid
Автор

Thank you for making it simple. God bless you!

chriseyemd
Автор

You speak sooo clearly making most difficult topics easier.talenttt

mahnoorayaz
Автор

This is the best explanation of electron transport chain! I thought Khan academy was better but you are even better! :-)

HitanshuTheBoy