7

Aren't there any other alternatives for this acceptor? Not that we're aware of. Every other alternative requires an anaerobic environment - which means small, and often less efficient. Oxygen is already recognized to have several harmful effects to cells - wouldn't another molecule be a better choice? When we're talking about a molecule's fit there are ...


6

Avoiding diffusion is one reason to phosphorylate glucose, the other is that it is removed from the osmotic balance between inside and outside of the membrane, so it can be transported at a high rate. The Glucose-6-phosphate can then be used as a substrate for different pathways, namely glycolysis and the pentose phosphate way, and (depending on the ...


6

Difference between Ubiquinone (UQ) and Plastoquinone (PQ) Structural Difference: Structurally, UQ and PQ are very similar. They only differ in a methyl group and 2 substituents on the benzoquinone ring (Liu et al, 2016). See the image for comparison: Functional Difference: Functionally, PQ and UQ are very different. I'll give some differentiation points: ...


6

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 is found in smaller amounts in vegetables and fruit, as well. Adenosine can be found in many of the same foods, both as free ATP/ADP/AMP, and as part of the DNA ...


6

I'll give it a layman's attempt in sort of an "ELI5" approach. I hope the analogy isn't too simplistic, and please don't take it too literally. How do plants use K+? Plants control K+ concentrations and do work within the plant by pumping K+ between different compartments. Because water tends to follow solute concentrations (osmosis), plants can do things ...


6

The passage of protons through the FO (membrane) portion of the molecule (driven by the electrochemical gradient of protons across the respiratory membrane) generates torque at the interface between the a and c subunits. This mean that the ring of 10 c subunits rotates relative to the a subunit. The γ subunit in the stalk rotates along with the ring of ...


6

Aren't there any other alternatives for this acceptor? Yes, there are multiple other acceptors used by anaerobic bacteria. Iron is probably the most common other acceptor used by a range of organisms in a range of environments but others are used as well, such as sulphur. Aren't there any other alternatives for this acceptor? Oxygen is already recognized ...


6

Summary The original question was edited — with the approval of the poster — so that in brief it now asks: Why is ATP hydrolysis to ADP, rather than ADP hydrolysis to AMP, the normal way in which cells drive reactions which alone involve positive changes in Gibbs Free Energy? The scope of this is wider than that originally assumed in the answer ...


5

Short answer (A) is a possible answer and is indeed cause for fatigue, as pyruvate is needed for the Krebs cycle to run. The krebs cycle is an essential step in the generation of ATP in aerobic organisms. (B) is incorrect because NADH is never transported into the mitochondria in any organism (it is a nonsense answer). Background NADH is not transported ...


5

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 obligate anaerobic bacteria still had the electron transport chain (ETC) and ATP synthase as there were different electron acceptors other than oxygen. Yes, we know ...


5

Both statements are correct, but an understanding of why they are not contradictory requires a bit of explanation. For "spontaneous" reactions, those which occur naturally, entropy must always increase. As a general rule, one of the easiest ways to increase entropy is to release energy, so we generally find that spontaneous reactions release energy.* It's ...


5

The rate of CO2 production is normally set by the rate of metabolism and breathing rate is determined by the level of CO2 in the blood. What you are suggesting is known as hyperventilation. Because blood CO2 plays an important role in maintaining the pH of the blood, hyperventilation can lead to a dangerous increase in blood pH, referred to as respiratory ...


5

It can, and a very famous example is polynucleotide phosphorylase, an enzyme of great historical importance in the elucidation of the genetic code. That said, it is very uncommon, and polynucleotide phosphorylase is the only example that I know of (but other users may be able to provide additional examples). There is certainly no thermodynamic reason ...


4

Yes, the energy from ATP hydrolysis can vary between different cell types and condition, because it depends on several factors. Hence, you will find different values in various textbooks. First, like any chemical reaction, the free energy $\Delta G$ of ATP hydrolysis depends on the concentrations of the reactants. You can explore different values of $\Delta ...


4

Unlike mammals, saurischian dinosaurs don't have to chew their food. Like birds they have a gizzard to do that instead. Look at a modern ostriches: they have a very small head because the head is only used to gather food not process it. Mammals process food in the head (chewing) so the head has to be large to support the muscles, teeth, and other apparatus ...


4

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 Berg et al. are suggested.) The production of NADH in the oxidation of carbohydrates and fats is the energetic rationale for these processes. Under aerobic ...


4

General Approach Although I am not an expert in this area, as an ex-chemist I find this topic one of the most fascinating and fundamental in chemical biology. I have constructed an answer starting from my copies of the 5th (available on line) and 6th editions of Berg et al. Biochemistry (2003 and 2007, respectively), and then searched the Protein Data Bank ...


4

Preamble The question suggests unfamiliarity with the nature of biochemical oxidations and their relation to energy transfer in biology. The naïve reader is recommended to consult a text for a coverage of this subject: all I feel is appropriate here is a general summary followed by a brief indication of the key reactions. General principles of energetic ...


3

I just want to add a slight clarifying point to the previous member's already great answer. Keep in mind that these 10 protons that are pumped into the intermembrane space by the end are per one molecule of NADH. So each molecule of NADH will result in 10 protons being transported into the intermembrane space (as previously stated). For each molecule of ...


3

It seems like the mistake is in complex III. Look at this image from here: It clearly shows the number of protons reduced in (and taken from) matrix and number of protons pumped into inter-membrane space. So the data becomes: Complex I: matrix: 2H+ reduced (from NADH + H+) + 2H+ pumped out IMS: 4H+ pumped in Complex II: matrix: 2H+ reduced (from ...


3

Your (original) description: a kinase helps chemically deliver or metabolize stored energy within a cell sounds a little more like what many ATPases do: they are using the energy from ATP to do some energetically unfavorable work, such as moving molecules or ions against their concentration gradients. However, kinases have a broad range of different ...


3

It is theoretically possible but no known organisms does it. The problem is you need a pretty strong and persistent temprature gradient to generate usable work out of it, and those are not that common in nature.


3

If there is no glucose there is no need for glycolysis: I deduce from this truism that – at some early stage in the evolution of metabolism – a pathway resembling gluconeogenesis must have arisen before glycolysis. This is just another way of stating the obvious fact that autotrophy must have preceded heterotrophy. If the aldolase reaction for triose → ...


3

You have to consider the full redox reaction to determine if the reaction is favourable or not. It's not correct to think of enoyl-CoA alone as "higher energy" than acyl-CoA, because of the free energy difference $\Delta G$ of the half-reaction: acyl-CoA $\leftrightarrow$ enoyl-CoA + 2 $e^-$ cannot be determined without knowing what the electron acceptor ...


3

Erythrocytes are far more than inert "bags" of oxygen. They are complex, highly specialized cells and, like all cells, they require a number of basic processes to be maintained to work properly. A good example (out of many) of why red blood cells need energy would be the active transport of ions across the membrane, a mechanism important for any type of ...


3

You are not going to get an exact number because of variation in body mass, age, sex, and metabolism. life style also has a huge effect,what someone doing hard labor needs is vastly different that what a comatose person needs. Minimums are harder because of the ethical problems with studying the bare minimum humans can survive on long term. The best you ...


2

ANSWER SUMMARY The criterion of efficiency of mitochondria is taken as the yield of ATP per carbohydrate molecule oxidized using the electron transport chain and oxidative phosphorylation. Experimental values for this are similar for yeast and humans, whereas theoretical values derived from differences in the structures of the ATP synthases actually imply a ...


2

Although there is no net oxidation or reduction in glycolysis, a constant supply of NAD+ is (paradoxically) required in order for glycolysis to continue. Otherwise, the glyceraldyde-3-phosphate dehydrogenase reaction (GAPdh) could not generate 1,3-diphosphoglycerate. So how is the NADH generated in the GAPdh reaction converted back to NAD+? Both alcohol ...


2

Disclaimer Although this question appears to be either unclear or unanswerable (or both), and shows no evidence of research on the poster’s part, I have chosen to address one aspect of it to emphasize a general concept. This, despite the fact that my knowledge of nuclear transport processes is minimal. Brief Answer GTP, rather than ATP, is used for ...


2

Disclaimer: Not a doctor, a biologist, or a scientist. This TEDx talk by Ruben Meerman explains the process of the mass loss via CO2 via exhaling. The mathematics of weight loss | Ruben Meerman | TEDxQUT (edited version) His explanation to increasing CO2 by-product of oxidizing fat was to increase O2 intake by raising your heart rate. This raises your ...


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