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45 votes

Why isn't Fluorine, or Neon, the final electron acceptor in cellular respiration?

One of the main reasons that modern(!) biology uses oxygen as an electron acceptor is availability. Around 2.45 billion years ago, oxygen (O$_2$) started being built up in the atmosphere (which ...
Nicolai's user avatar
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32 votes

Why isn't Fluorine, or Neon, the final electron acceptor in cellular respiration?

Availability and applicability. Availability. In the beginning, there was CO2. It was abundant in the atmosphere, and later, the oceans. Fluorine and neon weren't, and so respiration evolved around ...
DevSolar's user avatar
  • 556
15 votes

Why isn't Fluorine, or Neon, the final electron acceptor in cellular respiration?

The atomic radius of fluorine is just slightly larger than that of carbon. When a fluorine atom bonds to a carbon atom that is part of a carbon backbone, the fluorine atom covers up not only the C-F ...
DrSheldon's user avatar
  • 511
11 votes

What is the ultimate source of ADP/ATP in humans?

Phosphorus is a very common nutrient, found in high levels in proteins, which are in such foods as milk and milk products, meat, beans, lentils, nuts, and grains, especially whole grains. Phosphorus ...
MattDMo's user avatar
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11 votes

Why is ATP synthase sometimes referred to as ATPase?

The way we were To understand why you may encounter ATP synthase referred to as ATPase, you need to be aware of the historical context — the experimental work that preceded the knowledge of the ...
David's user avatar
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10 votes
Accepted

Why do zoologists classify sponges as animals rather than plants?

Organisms are classified, not by their behavior, but by their phylogeny (evolutionary relationships). Sponges have unique and complex molecules in their intracellular matrix that developed in a common ...
Karl Kjer's user avatar
  • 7,693
10 votes
Accepted

Is pyruvate considered a high energy molecule like ATP or NADH?

Summary Do not use the term ‘high-energy’ to refer to biochemical intermediates because many people (including the OP) do not understand what it is supposed to mean. However, if you insist in using it ...
David's user avatar
  • 26.3k
9 votes

How many molecules NADH are produced in the Krebs Cycle?

This is slightly depending on which reaction you want to include into the cycle. I count four: One when Pyruvate is converted to Acetyl-CoA, one when Isocitrate is converted to α-...
Chris's user avatar
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9 votes

Why is carbon dioxide produced in alcohol fermentation but not in lactic acid fermentation?

Glycolysis needs a steady supply of NAD+ to happen - this is the driver for the anaerobic oxidation to lactate and ethanol, although this is energetically much less favorable than the complete ...
Chris's user avatar
  • 51.7k
9 votes

Why isn't Fluorine, or Neon, the final electron acceptor in cellular respiration?

Neon just does not work as an electron acceptor. It is that inert that there are currently no known Neon compounds at all. Fluorine would work in principle, but it is rare compared to oxygen and its ...
Sir Cornflakes's user avatar
7 votes
Accepted

Violation of the law of energy conservation between photosynthesis and respiration?

The Fallacies in the argument The question contains two main fallacies (some would say sleights of hand) in the energetic comparison of glucose synthesis from CO2 in the Calvin cycle and glucose ...
David's user avatar
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7 votes

How can the leakage of mitochondrial protons generate heat?

Uncoupling ATP synthesis from the ETC (electron transfer chain; this is where oxidation takes place) by thermogenin or any other method means that the energy used to generate or uphold the proton ...
Nicolai's user avatar
  • 4,391
7 votes

Why is ATP used as a source of energy rather than glucose?

Well the mechanics of this can actually get pretty complicated, depending on how far into the biochemical weeds we want to go, but there are a couple of very simple reasons at the core... Well they ...
Jeremiah's user avatar
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6 votes
Accepted

Does the formation of water inside the mitochondrial matrix help contribute to the proton gradient during the electron transport chain?

Your description of it is largely correct, but the electron transport chain does not simply "dump" charged oxygen ions in the mitochondrial matrix. Instead, cytochrome C oxidase (complex IV) binds the ...
Roland's user avatar
  • 5,725
6 votes

How much oxygen does a plant use up at night?

Roughly, half of the CO2 assimilated annually through photosynthesis is released back to the atmosphere by plant respiration (Gifford, 1994; Amthor, 1995). Source: https://academic.oup.com/aob/...
aesthete's user avatar
  • 351
6 votes
Accepted

Facultative anaerobic organism

There are organisms with anaerobic metabolism that tolerate oxygen: aerotolerant anaerobes. "Anaerobic" refers to the metabolic system. You cannot be sure of oxygen tolerance based solely on ...
Willk's user avatar
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6 votes
Accepted

ATP production via aerobic respiration

In short, the difference stems from different values regarding the number of ATP attributed to the electron carriers in the electron transport chain (ETC). My guess is that your class didn't go too ...
SmallFish's user avatar
  • 166
6 votes

Is there any organism that is born with all the nutrients and resources needed for their entire lifetime?

You may need to clarify your question: As written, this would be the biological equivalent of a perpetual motion machine. No such organism could reproduce without either violating the first and second ...
Alex Reynolds's user avatar
5 votes
Accepted

Why does ATP contain ribose rather than deoxyribose?

Short answer: The pentose ring does not participate chemically in the energy transfer reactions involving hydrolysis of ATP to ADP. Enzymes that catalyse these reactions would tend to be specific ...
David's user avatar
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5 votes
Accepted

Do sulfate reducing bacteria ingest their sulfate as solid, or as dissolved in water?

Sulfates in water would not be liquid. Their melting points are far to high. When a sulfate dissolves into sulfate ions and some cation such as potassium, we say it is solvated, not liquid. Sulfates ...
bpedit's user avatar
  • 1,351
5 votes
Accepted

Is glycolysis the beginning part of fermentation, or does fermentation follow glycolysis?

As @bpedit indicates in his comment, this is a semantic question — i.e. one regarding the meaning and usage of words. I will explain how I and others use these words and why. If you are convinced by ...
David's user avatar
  • 26.3k
5 votes

Why do bacteria produce H₂O₂?

why does the bacteria produce H2O2 in the first place? It is produced by all organisms as a byproduct of respiration. See this wikipedia article: All living ...
another 'Homo sapien''s user avatar
4 votes
Accepted

Do acetic acid bacteria use the electron transport chain when converting ethanol to acetic acid?

Yes I find it somewhat ironic that in a response a recent post from the poster concerning itself with the precise definition of ‘fermentation’ I argued that this was a semantic question because of ...
David's user avatar
  • 26.3k
4 votes

What is the fate of NADH produced in the liver during oxidation of lactic acid?

The “best guess” in this question is incorrect and the question itself indicates a lack of understanding of the roles of NAD+ and NADH in energy metabolism. (To rectifiy this, Chapters 17 and 18 of ...
David's user avatar
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4 votes
Accepted

Intermediate of Krebs cycle that can form Chlorophyll?

The standard treatment of this topic is covered in Section 24.4.3 of Berg et al., available freely online: Succinyl CoA is a precursor for porphyrin in mammalian cells by condensing with glycine to ...
David's user avatar
  • 26.3k
4 votes

Why is ATP used as a source of energy rather than glucose?

To understand this answer to the question one needs to have an elementary acquaintance with glycolysis and the concept of free-energy change in chemical reactions. This can be obtained from ...
David's user avatar
  • 26.3k
4 votes
Accepted

What are the differences between mammal and insect digestion of cellulose?

Update 2 (interpreting "faster" in terms of efficiency because it seems easier to measure) The question has been updated but I still don't see a reference for insects being more efficient than ...
Maximilian Press's user avatar
4 votes

Plant respiration produces carbon dioxide, so why are plants regarded as decreasing its atmospheric concentration?

There are two factors here. First is that you have to look at the plant's net production over time. Say for instance (I'm just making up numbers here) that during the day the plant takes in 88 g of ...
jamesqf's user avatar
  • 3,653
4 votes

Oxygen uptake with gills from water vs lungs from atmosphere

The assumption in the question was corroborated by this article here, and is correct. The downvote is unnecessary, it is a valid question, and was easily answered with strong scientific consensus. ...
Winstan's user avatar
  • 111

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