New answers tagged

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It sounds like you are asking about the activation energy of the ATP hydrolysis reaction. This paper estimates the activation at 35--39 kcal / mol, depending on details of the reaction mechanism. So yes, energy is needed to break the phosphate bond; this ensures that ATP does break down spontaneously (which would make it a rather useless molecule for cells). ...


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The straight forward answer is: we don't know. We don't have any direct evidence for what happened at that time nor any completely developed and coherent theories for how it worked. The widely believed hypothesis is the "RNA World" hypothesis. RNA, unlike DNA, is capable of spontaneously folding to form catalytic molecules and thus avoids the needs for ...


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I think you have misunderstood the "inside" part of the "positive-inside rule". Perhaps because "inside" is indeed an imprecise term (but now it is history and cannot be changed ;) ). In order to understand it a bit better it helps to think about the topology of the membrane. During synthesis most membrane proteins (ignoring peroxisomal and mitochondrial ...


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I think GPCRs are evolutionary more older since tyrosine kinase signalling is relative recent evolved system. This could be one explanation for why their is more diversity in GPCRs By the way GPCRs can actually signal g-protein independent, for example via B-arrestin. Also their are many types of g-proteins witch can all induce signaling via different ...


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Actually citric acid is not only available in citrus fruit but also in pretty much any living thing. it is an important intermediate in Krebs cycle, but I guess the main reason that it is available in high concentrations in citrus fruits is because citrate is an inhibitory compound for phosphofructokinase, that means it stops the glycolysis and hence it ...


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I would argue the all-or-none principle is a rule of thumb. It is generally true if voltage hits a certain threshold then there will be a action potential with the same amplitude regardless the strength of the stimuli. But as you point out with the logic gate example, the threshold is notoriously hard to define mathematically. Furthermore Action Potentials ...


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For allosteric inhibition, the inhibitor binds to the enzyme and induces a change in the conformation so that the substrate cannot bind anymore. The binding site for the allosteric inhibitor is different from the substrate, see the image for illustration (from here): In non-competetive inhibition the inhibitor also binds to the enzyme indepently of the ...


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According to this paper, green pigments are found in lepidoptera. The study focused on Geometridae, and found that the primary pigment in emerald moths, such as Hemistola chrysoprasaria is also found as secondary pigment in Pseudoips prasinana. The authors dubbed the substance 'Geoverdin' and suggest it may be a derivative of chlorophyll consumed during the ...


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Inhibition is rarely binary - it's almost always subjected to stoichiometric effects. So the answer could be either option, depending on the amount of the inhibitor present in the system. If there is a huge amount of the inhibitor in the cell, it may more or less completely ablate ATP production by the ETC. On the other hand, if there isn't enough of the ...


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An example of an enzyme with a cofactor would be any of the Cytochromes, they contain an Iron ion which alternates between its Fe2+ and Fe3+ states in redox reactions. This is why cytochrome is used in the aerobic electron transport chain.


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Apart from what Phototroph mentioned in their answer (competitive and non-competitive inhibition), an enzyme can be activated/inhibited via covalent modification of the protein (post-translational modification) such as phosphorylation by protein kinases (phosphorylation is the most common modification).


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Yes, competitive inhibition is another form of enzyme inhibition. The inhibitor binds to the active site here, as opposed to allosteric inhibition, where it binds to a secondary site. An example of an inhibitor would be the cyanide ion (CN-), which inhibits Cytochrome C oxidase, preventing electron chain transport and thus ATP production. Note this ion is ...


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BWA-mem (like most aligners), takes a normal single-stranded fasta file (I've never seen one with both strands listed) and aligns to both strand.


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These are somewhat loosely defined terms, but I would say catabolism is any metabolic process that extracts energy from a substrate. Ethanol conversion to acetate (via alcohol dehydrogenase; see this schematic) is an oxidative pathway which extracts energy in the form of NADH, so yes, it is a catabolic pathway. I guess you can also call this process ...


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Short answer: Only some stages of plasmodium are motile. These use "gliding motility". Gliding motility relies on actin filaments, which enable the organism to deform it's shape, facilitating movement. This video provides a good visual representation of the filament-based motility. "Gametocytes develop into gametes in the insect midgut, and then ...


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FADH2 substrate does increase the H+ gradient by 6, and so increases the ATP Synthesization "potential" by about 1.5 (6/3.3). the difference between the NADH and the FADH2 substrats are mainly the different path in the electron chain. NADH uses Complex1, and FADH2 is part of Complex2, which have different ability to to pump H+ out. (but of course there are ...


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the electron transfer potential is based on the difference in the affinity of elements/molecules to bind electrons. the affinity of the element derives from it's components as shown in the elements table, just like all other characteristics. for example, oxygen has higher affinity to bind new electron than carbon. the affinity of the molecule derives from ...


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The major hurdle for novel treatments to make it into humans is the assessment of its merits and added value over existing, proven treatments. And more importantly, the safety for humans has to be validated to a sufficient extent. The notorious from bench to bedside (Goldblatt & Lee, 2010) bottle neck. To answer your questions: Technically, going from ...


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The vector used in this study is based on the herpes simplex virus genome (HSV). Wildtype HSV mainly infects sensory neurons. After infection, it resides in a latent state in the nervous systems of the host for a lifetime. The viral genome persists in the cell, without integrating into the host genome (Marconi et al., 2000). The article cited is devoid of ...


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Each of us burns approximately twice our body weight in ATP every day. So double your body weight and divide that number by the number of seconds in one day; that will give you the average mass of ATP. N.B. a person with a higher mass will have a higher answer.


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ATP burned per minute is not a useful number because the turnover is so high. 2000 kcal/day is dozens of kilograms of ATP so obviously ATP is turned over more than once a day, but there's probably more than one molecule of ATP being passed around between all the ATP synthases. This blog claims 250 grams. Taking the estimate of ATP concentrations(1-10 mM) ...


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I suspect this is a product of differentialy expressed glycosyltransferases. Instead of adding a sialic acid, for example, if you're coding for Enzyme B which is an alpha 1-3-galactosyltransferase, you're going to add a Gal to the glycan chain forming B antigen, and so forth. Sialyltransferases can add sialic acid groups, but to the same structure it looks ...


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Chaotropic agents are cosolutes that can disrupt the hydrogen bonding network between water molecules and reduce the stability of the native state of proteins by weakening the hydrophobic effect. a chaotropic agent reduces the amount of order in the structure of a protein formed by water molecules, both in the bulk and the hydration shells around hydrophobic ...


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Yes steroids are a class of lipids which include cholesterol and sex-hormones such as testosterone and estrogen. Only vitamin-D belongs to the class of steroids. Vitamins A, E and K are isoprenoids. In fact even steroids are synthesized from simple isoprenoids. You can refer to a standard biochemistry book to understand steroid biosynthesis pathway. There ...


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MD simulations. Molecular Dynamics algorithms like Gromacs and AMBER aim to simulate atomistic mechanisms of biological macromolecules. This video shows a good example of a resulting video from such a simulation for the CmAAT1 Enzyme, CmAAT1-Hex-aCoA complex. Much more data such as energy values and electrostatic interactions is available from the ...


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There are a lot of differences, you can check the companies that sell competent cells for guides on how to choose (NEB, Sigma Aldrich). But there are only a few things that matter for the really common uses of competent cells. The most important part of selecting your cells is choosing cells suitable for protein expression or for plasmid preparation. The ...


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TL;DR: An expected efficiency for a typical PCR is 80%, meaning each cycle multiplies the copy number of the targeted DNA sequence 1.58 times. Firstly, it makes more sense to refer to the amount of DNA in a polymerase chain reaction in terms of copy number or in terms of moles; the number of DNA molecules of interest is what the reaction is operating on, ...


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I am not experienced in the topic, and could not find any article related to these kind of reactions, but my guess is the following. During the nuclear transmutation the radiocarbon will lose an electron (beta particle), so the nitrogen product will have positive charge. After that there are 2 possible scenarios. a.) less plausible scenario The beta ...


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The phosphate group/s present in the mononucleotide or nucleic acid result in the structure having an overall slightly negative charge. Positively charged proteins that are also present in the cell such as histones help to keep the negatively charged nucleic acid stable 'in vivo'.


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Pyruvate transfers an acetyl group to coenzyme A. The acetyl group from acetyl co-A is the molecule that provides the 2 carbon atoms that get added to oxaloacetate to form citrate, and as you said, citrate starts the cycle over again. Without coenzyme A, pyruvate cannot transfer the acetyl group to oxaloacetate to form citrate so without coenzyme A/acetyl ...


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If they perform the exact same function, they can be considered the same functionally. Hemoglobin in most humans is the same, down to the amino acid sequence; the hemoglobin in sickle cell anemia, Hemoglobin C, Hemoglobin SC, thalassemia, and others are all different by at least one amino acid, yet they are all hemoglobins, and all do the same job: they ...


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Human and mouse titin are orthologs, and can be confirmed through an NCBI query for TTN. Orthologous proteins are not the same, per se. They retain the same function, and basically result from speciation: the common ancestral gene got divided between two species. However, the sequence may potentially differ because obviously the species have diverged. ...



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