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The quick answer is that only certain cell types express the required steroid hormone receptors that are necessary to induce signaling and gene regulation when bound to their target steroid hormones, like estrogen, testosterone, cortisol, etc. If no receptor is present, the steroid doesn't effect any change. The second part of the answer involves the ...


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Brain's main energy source is glucose. It uses about 20% of total glucose [1]. Brain hypoglycemia causes depressive-like behaviors in mice through adrenergic pathways [2]. When it comes to humans, here is a study that claims low glucose leads to increased aggression in married couples (see this too): Self-control requires energy, part of which is ...


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This is mostly because of the nature of the amino acids. You need to have a Hydroxy-group in the sidechain of the amino acid which is the point where the phosphogroup is attached. Since this process needs to be reversible, this can only happen here. See the image below (from here) about the chemical structure: In eukaryotes not only these three are ...


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Phosphorylation requires a nucleophile and hydroxyl oxygen acts like one. Serine, theronine and tyrosine get phosphorylated on the free $OH$ group in their side chains. Nitrogen, in some cases also can act as a nucleophile. In case of histidine, the imidazole nitrogen is phosphorylated during bacterial chemotaxis signaling. As far as I know eukaryotes do ...


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The article referred to in the question is Fromme et al. (2004). I was able to find several proposed mechanisms for the monofunctional uracil-DNA glycosylase but I'll discuss two that seem most relevant in the context of your question. The first I'll mention was outline by Parikh et al. (2000) who studied recombinant human mitochondrial uracil-DNA ...


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The condensation is not done in water alone - the enzymatic function of the ribosome plays the essential part here. And in the active center of the ribosome where the formation of the peptide bond takes place, no water is present, only the growing peptide chain and the single amino acid (bound to the tRNA). See this schematic image from the Wikipedia: If ...


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You are mixing things. First: Codons have nothing to do with the synthesis of amino acids. A codon is the sequence of nucleotides on the DNA (or RNA) which code for a certain amino acid. For example UGU and UGC code for the amino acid Cysteine and given these codons it will appear in the protein being synthesized. The codons are basically a way to code the ...


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Those residues are phosphorylated because they have a free hydroxyl group available to be bonded to a phosphate. Many other resides can be modified, like acetylation of lysines, but only those residues are chemically compatible with reversible phosphorylation.


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This is a short review about the issue and not complete. This and the earlier answer are not proofs of the link between the two proceses. To investigate this better, I think it would be much easier first to narrow the case to testosterone and energy homeostasis (Embryology; or better formulated research case) catabolism and anger anger and aggressive ...


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In general, if you want to know "exactly how much of X on an average is needed to be consumed to cause death", then the magic search term for Google is "LD50", that is the dose that kills 50% of victims. I've seen the LD50 for distilled water quoted as 90ml/kg for rats (that is, 90 ml per kg of body mass). I presume that figure comes not from theorising ...


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Though I totally agree with your views towards nanotechnology, There is always two sides of a coin. According to this article THE BAD (of Nanotechnology): Health: Nanoparticles have been shown to be absorbed in the livers of research animals and even cause brain damage in fish exposed to them after just 48 hours. If they can be taken up by ...


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Entropy is a measure for the number of states accessible to a system. The more states available, the higher the entropy. If you think of an atom confined in a volume V, then, without further restrictions, the atom can be anywhere inside that volume, i.e. the number of states will be a function of the volume V. The bigger the volume, the bigger the entropy. ...


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Ahh entropy. The bane of many undergraduates. You won't need a lot of mathematical rigor needed to solve for absolute entropies in most biological fields so it's best to think of it abstractly. Consider the atom. What can it do? Well if you remember from chemistry class, it can bounce around a process we call translate, and the electrons can basically ...


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As this table shows, the more complex a molecule is (in general) the more entropy it has. Entropy is an absolute quantity which is zero at $0^o K.$ When an atom or molecule has no way to rotate (is 'frozen') there is only one state in which it can exist. An atom of a gas or a molecule of a diatomic gas at $25^oC$ is also somewhat constrained compared to a ...


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It seems to me that you're asking about homology modelling. In that case, yes you need to compare your protein of interest to a protein (or proteins) of known structure. Homology modelling in a nutshell includes three (four?) steps: template identification/template alignment, modelling, quality assessment. You start with finding a template for your ...


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It is both, a and b. The JAK-STAT-Pathway sits below the Erb-receptor and is therefore giving the signal from mutated Erb down the signalling cascade. Besides that a permanent active version of Jak2 has been found which also permanently activates this pathway. Both are contributing to cancer. See this two articles: Molecular Pathways: JAK/STAT Pathway: ...


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DIY Diffusion Experiment This procedure was done to see what happens qualitatively when semipermeable (dialysis) tubing containing a solution of glucose and protein is immersed in a solution of glucose alone. Given that water would diffuse into the bag, the question to be answered was whether there would be an equilibrium increase of sugar concentration ...



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