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March 29, 2024, 08:50:28 am

Author Topic: the aerobic pathway  (Read 3313 times)  Share 

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bucket

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the aerobic pathway
« on: March 19, 2008, 06:42:33 pm »
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I have a question about the electron transfer stage, what exactly happens in this stage and how does it produce/recharge so many ATP/ADP molecules?
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munto

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Re: the aerobic pathway
« Reply #1 on: March 19, 2008, 07:59:44 pm »
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i'm not exactly sure of the exact process as it wasn't part of the study design (still isn't) and i haven't as yet gone to uni where it is examined more.

if you want the 100% honest answer, don't waste your time on it, the krebs cycle is the more important part of aerobic respiration. that being said, i'll have a look through my notes and see what i can dig up....

bucket

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Re: the aerobic pathway
« Reply #2 on: March 19, 2008, 08:12:07 pm »
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Oh awesome :P, thanks alot =].
If it isn't any trouble at all, could you give me your definition of the kreb's cycle?
My idea of what happens is pyruvate is oxidised to acetyl CO2 and two ATP molecules, is that all the knowledge I need to have of it?
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beezy4eva

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Re: the aerobic pathway
« Reply #3 on: March 19, 2008, 09:36:48 pm »
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i think all we need to know is that electrons from the loaded carrier molecules (NADH and FADH2) are brought into the cristae and are transferred from one cytochrome to another, releasing enough energy to produce 2-3ATP per electron. Then at the end of the 'chain' of reactions, a pair of electrons react with an oxygen atom (or 4 electrons and one oxygen molecule) to form O-2 which then reacts with the H+ to form water.
Note: as there are a total of 12 ELECTRONS that will wind up reacting and each can produce a max of 3 ATP thats where the 32 ATP comes from.
I dont think we need to know it in much more detail than that. 'Talking Molecules' has a fairly detailed description, if you've got that book.
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TrueLight

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Re: the aerobic pathway
« Reply #4 on: March 19, 2008, 10:49:31 pm »
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ok ill copy some of whats in the biology 6th edition campbell and reece text and then somehow make sense of it lolz goodluck but can i say its yr 12 you actualyl dont need to learn the inner grit of it, just like the main reactions that occur and its outputs

"The inner mitochondrial membrane couples electron transport to ATP synthesis: Most of the ATP made in cellular respirtation is produced by oxidative phosphorylation (((In the third stage of respiration, the elctron transport chain accepts electrons from the breakdown products of the first two stages usually via NADH and passes these electrons from one molecule to another. At the end of the chain, the electrons are combines with hydrogen ions and molecular oxygen to form water. The erngy released at each step of the chain is stored in a form the mitochondria can use to make ATP. This mode of ATP synthesis is called oxidative phosphorylation))) when NADH and FADH2 donate electrons to the series of electron carriers in the electron transport chain. At the end of the chain, electrons are passed to O2, reducing it to H20. Electron transport is coupled to ATP synthesis by chemiosmosis (((An energy-coupling mechanism that uses energy stored in the form of hydrogen ion gradient across a membrane to drive cellular work, such as synthesis of ATP))). At certain steps along the chain, electron transfer causes electron-carrying protein complexes to move H+ from the matrix to the intermembrane space,storing energy as a proton-motive force (H+ gradient). As H+ diffuses back into the matrix through ATP synthase, its exergonic passage drives the endergonic phosphorylation of ADP."

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DrowNz

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Re: the aerobic pathway
« Reply #5 on: March 19, 2008, 11:29:49 pm »
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I'll try to make a little sense of all this but you really gotta know and understand your terms to be able to grasp this process. So:
The production of ATP by the mitochondria: Food molecules are processed through
the Krebs cycle to produce electrons (e–) that are stored in NADH (a very important coenzyme found in the cell which participates in the carrying of electrons and cell signalling.)
The respiratory chain (aka electron transport chain) consists of three major components: NADH dehydrogenase, cytochrome b and cytochrome oxidase. The first component in the chain captures the stored electrons by separating NADH into NAD and H+. The electrons travel through the chain powering a pumping function of each component resulting in a proton (H+) concentration gradient across the inner membrane and are eventually transferred to oxygen (O2),leading to the production of water. The protons, moving down their concentration gradient, power the synthesis of ATP by the synthetase (you'd probably know it as ligase). The only exhaust from this power plant is water, which the cell uses, and CO2, a gas that is exhaled by the lungs.

This is a short recap we did for the electron transfer process in tertiary level, we didn't actually get into it yet. For year 12 I believe that beezy4eva pointed out what you need to know and that should suffice.
« Last Edit: March 20, 2008, 03:08:25 am by DrowNz »
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bucket

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Re: the aerobic pathway
« Reply #6 on: March 20, 2008, 12:19:36 am »
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Wow thanks for that explanation DrowNz!
And thanks beezy and stephanos for your explanations, they'll deffinitely help me with my summaries =]
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beezy4eva

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Re: the aerobic pathway
« Reply #7 on: March 20, 2008, 05:51:06 pm »
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bucket if u do chem it might be easier to think of it as a redox reaction where:

3O2 +12e- ---> 6O-2 and then
6O-2 +12H+ ---> 6H2O

Where the electrons and hydrogens are coming from the NADH and FADH2. And since a transfer of electrons releases energy thats where the energy for the ATP production comes from. But rather than the electrons being transfered in one step and all the energy being released at once, they're carried from cytochrome to cytochrome before finally reacting with the oxygen so that the energy is released less quickly and some can be used to form ATP.

*this is how i think about it, and it may not neccessarily be right.*
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Ninox

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Re: the aerobic pathway
« Reply #8 on: March 20, 2008, 11:25:46 pm »
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btw, I reckon the structure of the enzyme ATP synthase is pretty cool :P
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DrowNz

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Re: the aerobic pathway
« Reply #9 on: March 22, 2008, 04:24:43 am »
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But rather than the electrons being transfered in one step and all the energy being released at once, they're carried from cytochrome to cytochrome before finally reacting with the oxygen so that the energy is released less quickly and some can be used to form ATP.
Just wanted to add to the following comment something that could help explain why it is carried out the way it is as I find it quite crucial for the understanding of Biology.
Since the prebiotic era prokaryotes (first cells, unicellular) had to solve a major problem: acquisition of energy, and the way they did it stays true today. In the biological world, cells tend to avoid chain reactions that liberate large amounts of energy at once as much of it is lost in the form of heat/light (as you already probably know, cells are highly efficient and they damn surely had to be to survive on the early Earth.) Therefore an intellegent extraction of energy is done carefully and gradually and is the job of the biological enzymes. Enzymes are specialists in picking molecules apart, supplying energy at each step of the way.The energy extracted can be used to perform immidiate tasks or stored for later use.
« Last Edit: March 22, 2008, 04:31:59 am by DrowNz »
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