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Percent of basal metabolic rate by organ (BC Campus Open Education): Liver and spleen : 27% Brain: 19% Skeletal muscle: 18% Kidneys: 10% Heart: 7% Other tissues (lungs, intestine, skin, bone, fat tissue, glands...): 19% Basal metabolic rate by 1 kg of specific organ tissue (kcal/kg of organ/day) (Table 5 from American Journal of Clinical Nutrition, 2010): ...


11

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 ...


8

Short answer Approximately 240 J on a daily basis. Background Ballesteros et al. (2018) modeled basal metabolic rates of insects. They reckoned that endotherms, like insects, basically use energy directly correlated to the number of cells, which is linearly correlated to their body mass. They checked their model with experimental data from Chown et al. (...


8

Physics answer that is a bit silly If you want to be real technical about physics, mass and energy are the same thing, so any chemical bond that has some energy and is broken results in a change of mass (mgkrebb's estimated in a comment the final mass would be 999.999999814 g, if you started with 1 kg of protein, also known to a very precise biologist as 1....


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 ...


7

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 ...


7

2nd law of thermodynamics states that the overall entropy of the universe cannot decrease at any time. This can also be stated as the fact that the universe naturally falls towards the lowest energy state, or equilibrium. This becomes important in metabolic reactions. Reactions which seem to increase the state of energy, or perhaps the 'order' of the ...


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

Some amino acids are essential, that is, they cannot be synthesized. For all the others, however, you need building blocks. Nitrogen, and specifically ammonia, is required for non-essential amino acid synthesis, the transfer of which is accomplished through a process called transamination. Amino acids are also broken down for energy as a metabolic process,...


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

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

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 ...


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

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 ...


6

Summary It is the nature of the biochemical reaction that determines whether a reaction of ATP involves hydrolysis of the β- or γ- phosphoanhydride bond. If a part of the ATP molecule is incorporated into one of the products, the choice of bond to be cleaved emerges from the chemistry of the reaction. If the hydrolysis (with a negative free energy change, ΔG)...


6

Summary The redox potential widely quoted in text books for the half-reaction reduction of FAD to FADH2 is indeed inconsistent with the observed direction of several reactions involving this coenzyme, including its reduction of NAD+ in the dihydrolipoamide dehydrogenase reaction. The reason for this is that the value quoted is determined for free FAD in ...


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

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

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 ...


5

Essential nutrients include (NutrientsReview): Water 9 amino acids: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, tryptophan, threonine, valine 2 fatty acids (alpha linolenic and linoleic acid) Vitamins: A, B1, B2, B3, B5, B6, folic acid, biotin, B12, C, D, E and K (and choline, which is considered a vitamin-like substance) Minerals: ...


5

The fundamental 'problem' with acetyl-CoA is that it cannot be converted to glucose via the tricarboxylic acid (TCA) cycle: a two-carbon compound (acetyl-CoA) enters the TCA cycle, but two carbons are lost as CO$_2$ during each round of the cycle (in the two decarboxylation steps, ie in the reactions catalyzed by isocitrate dehydrogenase and by the alpha-...


5

Summary The apparent paradox is resolved by the fact that not all tissues possess receptors that cause them to respond to glucagon or, more generally, to the same hormone. Where different tissues do respond to the same hormone, the tissue response may differ because of differences between the pathways or particular enzymes within the different tissues. ...


4

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 ...


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

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

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

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 ...


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

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 ...


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