The process in which energy is liberated from organic molecules producing ATP.

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Source of hydrogen in reduction of oxygen in electron transport?

What's the source of hydrogen in the reduction of oxygen to water in metabolism? Is this implying that half the hydrogen comes from NADH and the other half from lone protons?
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how we don't breathe nitrogen when it makes the most of air?

How we don't breathe nitrogen when it makes the most of air? Why we are always tend to breathe oxygen,not hydrogen and nitrogen?
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Where does the 'C' in exhaled CO2 mostly come from?

When a human being exhales $CO_2$, what is, by the numbers, the main source of carbon atoms exiting the body in this way? I mean what class of cells, or which tissues are the biggest on a pie chart of ...
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46 views

Missing 4$H_2O$s (per glucose) in Cellular Respiration… Where can they be?

I having trouble understanding the equation of the cellular respiration. The thing that bothers me is the number of $H_2O$ molecules. Generally, cellular respiration is written thus : $C_6H_{12}O_6 + ...
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What's the point of glycolysis in fermentation?

In order to get glycolysis started, you need 2 ATP. In the process, you can generate 4 ATP. That results in a net gain of 2 ATP. Hooray! But wait. If you don't undergo glycolysis, then you've got an ...
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Diffusion of FAD+

Why is NAD+ free to diffuse within the mitochondrion whereas FAD+ is not ? What biochemical properties cause this difference ?
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Why is succinate dehydrogenase attached to the inner mitochondrial membrane?

Succinate dehydrogenase is attached to the inner mitochondrial membrane.All the other enzymes of the Krebs cycle are located in the matrix of mitochondria. What is the biochemical reason behind ...
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Why can we breathe only oxygen?

Plants has the capacity to take in both CO2 and oxygen, that's during day CO2 and at night oxygen. Why don't humans have such a capability?
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How do the first and second law of thermodynamics adhere to breakdown of glucose?

I know the first law is energy can only be converted from one form to the other, therefore in the breakdown of glucose 40% potential energy is converted to ATP and 60% is converted to thermal and ...
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What are the molecular mechanisms that make the turtle brain more resistant to hypoxia?

I know that turtle brains, particularly those of individual species that hibernate and burrow are particularly resilient to hypoxia and any tissue damage secondary to a hypoxic event. What are the ...
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Breathing in and out

I was reading my textbook and it says that breathing involves inhaling and exhaling but it doesn't say whether they happen simultaneously or sequentially. Also is my overall understanding of ...
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Aerobic vs anaerobic respiration comparison

The following graphs compare glucose decomposition in yeasts (in anaerobic vs aerobic conditions respectively) My question is, why doesn't the first one look like a straight line as the second one ...
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Do fish break a water molecule to absorb oxygen?

How do fish separate oxygen from H20 & consume it? Do they break the water molecule and absorb the oxygen only?
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cellular respiration

What are the effects of addition of these chemicals to actively respiring cells ? Which of them would lead to INHIBITION of aerobic respiration ? Would cytochromes be actually taken up by cells ? ...
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Critical pO2 threshold for cell division?

I'm a physicist asking questions on an aspect of cellular metabolism, so excuse my biological ignorance! Hypoxia is a frequent complication of certain tumour types, and has quite an implication for ...
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NADH vs. NADPH: Where is each one used and why that instead of the other?

I know NADH is used in cellular respiration and NADPH is used in photosynthesis. What difference does the phosphate group make that the same one isn't or can't be used for both? Is there a greater ...
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208 views

Confusion regarding photosynthesis and respiration in plants

During 24 hours there is a time in i.e. twilight when plants neither give oxygen nor carbon dioxide why is it so? This also suggests that neither of the two vital processes i.e. respiration or ...
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Cell Respiration and Oxidative Phosphorylation

Why and how does the proton travelling through the stalked particle in the inner mitochondrial membrane, cause a conformational change in the ATPase?
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Could hydrogen replace oxygen in cellular respiration?

I was wondering what oxygen actually does in the body. I have seen a few answers to other questions that involve the electron chain and I am really not sure what that is. So I was wondering what ...
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Do cold blooded animals generate any heat?

In explaining energy and work to an 8 year-old I said that all conversion of energy generates heat as a by-product. For example, cars generate heat in their engines and running generates heat in our ...
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Why do red blood cells contain haemoglobin and not myoglobin?

So I am reading about muscles and I come across myoglobin. It has a much higher affinity for oxygen than haemoglobin. So why have animals evolved to have haemoglobin in red blood cells, rather than ...
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ATP in Glycolysis Vs Gluconeogenesis

In glycolysis, the conversion of glucose to pyruvate results in a net gain of 2ATP molecules. In gluconeogenesis however, the conversion of pyruvate back to glucose requres 6ATP molecules. Why does ...
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How is respiration an unbalanced equation

The equation for respiration is C6H12O6+6O2→6CO2+6H2O+36ATP. The chemical formula for ATP is C10H16N5O13P3. How is this possible, since it violates the law of conservation of mass because it is ...
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How do prokaryotes perform cellular respiration without membrane-bound organelles?

In order to survive, prokaryotes such as bacteria need to produce energy from food such as glucose. In eukaryotic cells, respiration is performed by mitochondria, but prokaryotic cells do not have ...
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Where is the line between Anaerobic and Aerobic?

I am well aware of traditional anaerobic respiration (lactic acid or alcohol produced - no Krebs cycle) and traditional aerobic respiration (O2 is used at the end of the Citric acid cycle). I am ...
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What preceded ATP synthase?

ATP Synthase is ubiquitous throughout life on earth and so most probably evolved within the last universal common ancestor (LUCA) before that lineage diversified into the various kingdoms of life. ...
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Is there an evolutionary reason for the 5 electron transport complexes in plants and animals?

The electron transport chains of both the light reactions of photosynthesis (in plants) and oxidative phosphorylation (in animals) both contain 5 complexes including ATP synthase, as shown below. ...
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Given ATP synthase's structure, how can 3.33 protons ultimately synthesize one and only one ATP?

I am familiar with the structure and function of ATP synthase, but one small detail doesn't seem to make sense. It also happens to be a detail that seems very hard to express. Depending on the ...
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Why does muscle tissue have relatively constant AMP + ADP + AMP?

I was going over slides of energy expenditure in muscle cells. It mentions that in muscle tissue, the cell's energy charge ([ATP] / [AMP]) is the principle factor controlling glycolytic activity, and ...
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538 views

Is there a relationship between efficiency of cellular metabolism and warm-blooded-ness?

My BIO 101 book states that when human cells convert glucose to ATP, the process is only approx 35% efficient, and much of the potential energy is lost as heat. However, that heat is useful to us in ...
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Why do neurons die so quickly (relative to other cells) when deprived of oxygen?

This question could be considered a follow-up question to Why is a lack of oxygen fatal to cells?, although the top answer there does not address why damage starts to pop in. The answer says this: ...
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How fast does the rotor in ATP synthase spin?

I'm sure the exact frequency varies, but does anyone know roughly how many revolutions per minute / second the rotating center part makes?
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What effect does ambient temperature have on the cardiovascular system?

I am sorry if this is not appropriate for this site, but I think it fits so I am asking it here: I went for a run yesterday, and it was about -8 degrees Celsius. I was wearing a couple pairs of ...
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What does the human body use oxygen for besides the final electron acceptor in the electron transport chain?

My biology teachers never explained why animals need to breathe oxygen, just that we organisms die if we don't get oxygen for too long. Maybe one of them happened to mention that its used to make ATP. ...
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951 views

How does the enzyme ATP Synthase use a proton concentration gradient to make ATP?

I understand what the enzyme ATP synthase does, but I'm not exactly sure how it does it. I've heard that it uses rotary catalysis, but how exactly does this work? How is the energy from the H+ ion ...
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Do mitochondria simply automatically convert glucose to ATP?

I wonder whether there is any intelligent decision-making in mitochondria in the timing of their operation. Do they simply begin ATP production as soon as the correct reactants are present? Or, ...
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What is the benefit for cells having the ATP production regulated in mitochondria compared to being from the nucleus?

Mitochondria have their own DNA and appear to be loosely connected to the nucleus and it role. Why are the functions of mitochondria not in the nucleus? Why doesn't the nucleus control the ...
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Why is a lack of oxygen fatal to cells?

In animals temporary anaerobic respiration leads to the breakdown of the pyruvate formed by glycolysis into lactate. The buildup of lactate in the bloodstream is accompanied by a large number of ...