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 ...
- 4,391
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 ...
- 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 ...
- 511
14
votes
Accepted
Why is ATP produced in photosynthesis used to synthesize glucose?
As far as I can understand your question, you wish to know why a plant cell consumes ATP to produce glucose when it can directly use the ATP as an energy molecule.
ATP is an energy currency and is ...
- 35.2k
13
votes
Accepted
Why does NAD+ become reduced if it gains a hydrogen proton?
You are correct that reduction is simply a gain of electrons. This results in a decrease in oxidation number.
You know that NAD+ is reduced by this process because it starts off with a positive ...
- 2,472
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 ...
- 15.2k
10
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 ...
- 24.1k
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 ...
- 24.1k
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-...
- 51.3k
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 ...
- 51.3k
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 ...
- 675
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 ...
- 24.1k
7
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 ...
- 7,647
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 ...
- 4,391
6
votes
Accepted
Why don't protons diffuse out of the mitochondria during chemiosmosis?
Diffusion, is by definition (Ficks Law) describing movement along or against some gradient (here its concentration) even if the mechanism of transport differ: active, passive, facilitated. The setup ...
- 397
6
votes
Accepted
Membrane Permeability to Pyruvate
Pyruvate is negatively charged and quite polar, which makes it unfavourable to diffuse directly through any membrane. The outer mitochondrial membrane contains porins, which allow small molecules, ...
- 17.6k
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/...
- 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 ...
- 2,974
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 ...
- 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 ...
- 5,568
5
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 ...
- 5,665
5
votes
Accepted
What product of cellular respiration creates an acid when in solution with water?
Cellular respiration itself, defined as the activity of the respiratory chain complexes I -- V (including ATP synthase), is not acidifying. On the contrary, free protons are captured during ATP ...
- 5,665
5
votes
Do all prokaryotes have ATP synthases and an electron transport chain?
This is an interesting question (I really mean this — see below), for which a straight answer is remarkably difficult to find on the web. When I googled for it I got pages with statements that ...
- 24.1k
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 ...
- 14.1k
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 ...
- 24.1k
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 ...
- 1,351
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 ...
- 24.1k
5
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 ...
- 349
4
votes
Accepted
Electron Transport Chain in Mitochondria
The good ol'electron transport chain (ETC).
Before beginning let us begin by looking at the structure of a mitochondrion and the purpose of the ETC.
(source: tokresource.org)
Take of note four things:...
- 205
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 ...
- 24.1k
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